A catalog of non-toxic building systems.
Monday, June 12, 2006
EcoNest - Creating Sustainable Sancuaries of Clay, Straw, and Timber
This recent book by Paula Baker-Laporte and Robert Laporte details these architects' current focus of work, the 'EcoNest' sustainable and non-toxic cottage based on their revival and improvement of the clay, straw, and post & beam 'wattle and daub' construction techniques common to traditional archiecture of Europe and Japan. Paula Baker-Laporte is one of US's few non-toxic housing specialist archiects and has been known largely for her work in the US Southwest using pumicecrete construction. She is also author of the book Prescriptions for a Healthy House, one of the important textbooks and sourcebooks for non-toxic housing. (mentioned previously on this site)
With EcoNest the Laportes present a detailed and lavishly photographed introduction to a method of construction and style of design that are not only sustainable and non-toxic but also exceptionally graceful and comforting in its organic aesthetic. More strongly inspired by the Japanese tradition of this construction method than by the European tradition, the homes showcased in this book seamlessly blend the sensibilities of traditional Japanese homes with those of contemporary sustainable design as well as the traditions of Southwestern design. Quite often I have observed that there is an interesting complimentary aspect to both Asian styles of design and indigenous Pueblo design which seems rooted in their mutual minimalism and veneration for organic materials. The few but growing number of designers devoted to what I call the 'organic by composition' aesthetic seem to have noticed this as well and in the more contemporary of sustainable home designs we often see hints of an Asian influence. But in these showcase EcoNest homes the Laportes' offer the most sophisticated expression of this to date. There is no mere mimicry and transplanting of the stylistic artifacts of Asian design -no sense of the 'Mikado stage set' that many attempts to employ Asian influence in contemporary design are reduced to- but rather a true integration of essential aesthetic in combination with the integration of fabrication technique, the result being a comfortable new pragmatic design sensibility well adapted to the particular mix of environments these homes have been placed in. Indeed, 'comfort' rather than 'luxury' seems to be the essence of these homes.
Unfortunately, those looking to this book for a detailed system of instructions for this clay and straw building technique and the design of homes based on it will be disappointed. This book is quite the light read and ultimately comes across as a very elaborate sales brochure for the Laportes' EcoNest-specific design practice. But then, these homes -as much as the Laportes give lip-service to their economy- are dependent on very skill and labor intensive techniques. These are homes crafted like art objects and it is highly unlikely that they could be produced by mainstream contract labor, be affordable to the mainstream homeowner, or be possible for the owner-builder without exceptional talent. Even as modest in size as they are, I doubt they could be produced within half a million dollars in the US at current rates for this sort of skill and labor. Thus, as beautiful as they are, they fail to offer any realistic solution to the needs of the vast majority of people with a practical need for non-toxic housing -a complaint I have had with other work by the Laportes' and the rest of the very small community of non-toxic housing designers.
Still, there is no question that these homes offer something very profound to the emerging culture of sustainable home design. There are few better demonstrations of the essence of the organic aesthetic.
An interesting new use for straw as a building material has emerged recently in the form of a system called Strawjet, now being developed at Ashland School of Environmental Technology. The use of straw bale for non-toxic housing has tended to be tricky due to the problem of residual pesticides on on all non-organic agricultural products and the need for great care in preventing any possibility of mold or pest intrusion in the rendering encapsulating the straw bales. This new technology offers a new form of straw construction that may reduce these problems, though at present much more field experience is needed to determine its non-toxic housing potential.
Strawjet is based on the use of a special winding and binding mechanism which allows a harvester to produce a continuous thick cable of dense compressed straw fiber which is woven into composite panels and pultruded into beams with a cementous encapsulant. Individual cable cores can be replaced with pipe to serve as in-wall or in-beam utility conduits. Some very interesting architecture has been proposed for this technology, though not yet demonstrated. All in all, a promising technology but still in its very early stages of development.
Sunday, February 26, 2006
Site for Quanitco Lustron Images
Relating to my past article "Lustron Mania" on the unique porcelain coated steel Lustron homes of the Post War period, this site was recently mentioned on the Lustron Homes Yahoo Groups forum and offers a collection of good color photos of the collection of Lustron homes built at the Quantico Marine base in Virginia -now focus of a relocation project by MCS advocates. The homes have been declared obsolete by the military and were slated for demolition but have attracted attention by Lustron enthusiasts, architectural historians, and MCS patients, leading to attempts at a program to have the donated and relocated. Looking at these pictures from 2003, I was surprised at the apparent good condition of these homes considering the US military's reputation with handling their obsolete buildings and structures. Unfortunately, with typical relocation and rennovation costs for these homes currently floating around $160,000, the prospect of availing oneself of one of these 'free' Lustrons is not necessarily a bargain.
Sunday, June 26, 2005
T-Slot Framing - Factory Automation Comes Home
This is one very promising type of construction system the author extensively studied and at first had abandoned for practical housing use. But recently introduced products have changed things, making this not only practical but perhaps one of the most sophisticated of all building technologies currently available.
Extruded aluminum T-slot framing was developed as a simple modular building system for use in laboratories and factory automation where it allowed for the quick design and assembly of support structures, enclosures and cabinetry, custom furniture, and various mechanisms. T-slot gets its name from the 'T' shaped slots which are formed in the sides of otherwise square or rectangular extruded profiles. These allow for the connection of pieces using special T-nuts and other fasteners as well as the attachment of an infinite assortment of specialty components. The slots also allow for the mounting of glass or opaque panels, grills, and screen in the slots, sometimes using rubber gasket inserts.
The virtue of T-slot over previous modular frame systems -such as Box Beam- is that it allows for the in-line attachment of frame parts so they need not overlap each other or get in the way of components attached to the edges of the frame. This allowed for much greater versatility and simpler design, although the T-slot profiles are more elaborate to manufacture and much more expensive. T-slot, because of its hollow core, also allowed for the integration of pneumatic components using the frame members as pressure supply lines. This made T-slot ideal for the construction of simple custom robots and automated machinery and a vast assortment of T-slot components just for that application have evolved. Though T-slot seems generally unknown to the average person, quite a lot of the goods we use daily went through machines made out of this.
Because it is made of aluminum, this author considered T-slot a logical choice for use in DIY non-toxic housing. Aluminum is largely inert, perpetually recyclable at a lower energy overhead than steel, needs no painting or other protection, and the components are light and assembled with simple hand tools needing no special skills so that even someone with diminished health -like most MCS patients- could manage some degree of sweat-equity. And its as easy to dissemble a T-slot structure as it is to assemble it, affording it the virtue of perpetual demountability and structural adaptation. This was potentially the most sophisticated means of home building available -a platform for a true plug-in architecture. But there were a couple of critical problems with it. Though it has been used in a supplemental role architecturally, the small dimensions of the typical T-slot profiles made it difficult to use for whole building structures. One had to either build trusses from it, build framing akin to conventional stick framing, or buy 'combination' profiles where the smaller profiles are bound together and filled with foam to make beams and posts of large size. All of those options were prohibitively expensive because the number of parts was so high, and compared to lumber of the same dimensions, T-slot is many times more costly. What was needed was a very large dimension T-slot profile -6" to 12" square- that could be used for the primary components of simple post & beam box frames. But no one made this. The manufacturers of T-slot had never encountered a demand for such large profiles and had never seriously considered the use of their product for construction.
However, this year (2005) things changed with the introduction of two architect-designed modular home products based on brand new large dimension T-slot profiles. One is called Tomahouse and the other the iT House. Products of the current Modernist Pre-Fab housing craze, these ultra-Modern kit homes finally realize the potential of T-slot framing for construction, using simple pavilion designs based on simple post and beam structures just as this author had previously imagined. Somehow the designers of these homes managed to do what this author could not; convince T-slot makers that there was a point to and market for housing made from T-slot profiles.
Of the two the Tomahouse is the more sophisticated in that its designer has developed a modular home system with interchangeable components and a core pavilion module which is combined in various ways to produce homes of any size. The iT House is more concerned with a single one-size-fits-most minimalist home design that is pre-fabricated and marketed like a single large appliance. Though their designs hint at it, they do fall short in realizing the potential of T-slot as the basis of a plug-in architecture.
The basic idea behind plug-in architecture is that the structure of a home is a standardized modular 'backplane' akin to the backplane or motherboard of a personal computer. The objective is to not simply produce one or two clever designs but rather to cultivate a vast catalog of diverse components made by innumerable manufacturers that directly integrate into this backplane like the plug-in expansion components of a computer and can easily be installed and removed by the end-user/home-owner himself with no special skills necessary. For instance, wall, floor, and ceiling panels could be complete integrated appliances including TVs, home computers, kitchen and bath appliances and fixtures, heating, etc. The potential for built-in furnishings is unlimited. These would be simple modules that a home owner can himself plug-into the basic frame of the house with simple tools much as he does adding a new peripheral to his desktop computer. This is what T-slot has very successfully done for the industrial automation and laboratory equipment markets. It can do it for housing too, if one is clever enough to realize it. At the moment, though, only these two design companies are doing anything for housing with this technology. None of the innumerable manufacturers of industrial T-slot add-on components have caught onto this idea.
As the basis of non-toxic housing, since these two kit home products are still the only places one can obtain these components they are the only off-the-shelf option. Luckily, both of them are pretty low-toxic as-is and could be easily made fully non-toxic with a few minor substitutions in finishing materials. The Tomatek company seems the most amenable to this notion. The designers of the iT House are very fixed on their one and only design and are likely to be less flexible. Both are modestly priced, though still rather expensive for the typical MCS patient. If competition should develop in the future and more manufacturers wake up to the market potential, the price of these may decline.
Saturday, June 25, 2005
Shipping Containers - Superbox
This housing concept has been the focus of much research by this author and by a large number of architects, designers, and DIY tinkerers world-wide. There is something strangely fascinating about the simple, cheap, ubiquitous, tough, and inherently modular shipping container. And it has been used extensively for housing worldwide, both makeshift and with the benefit of sophisticated architectural design. And there is seemingly great potential for non-toxic housing since these containers are made of metal and, in their insulated form, have stainless steel interior skins and aluminum plank flooring. But it seems that the adaptation of these to housing use varies greatly, ranging from the simple to the complex, the cheap to the impossibly exorbitant.
There are basically four kinds of shipping containers. The most common is the dry goods container which consists of a steel box frame enclosed by corrugated steel panel and with an open floor fitted with wood plank like the inside of many cargo trucks.
Next is the insulated container which has a steel box frame enclosed by flat welded sealed sandwich panel with aluminum, fiberglass, or steel on the outside, stainless steel on the inside, insulating foam in the middle, and a floor of extruded aluminum plank. These containers also often feature a recessed bulkhead on one end designed to mount a refrigeration unit.
Next is the open frame container which consists of a standard container box frame without walls or roof and retrofit mounts for tanks, bins, and machinery. These are very diverse. They are used for large portable machines like generators, for fluids and bulk granular materials, tanks for live fish, and more.
Last is the flat bed container. Not really a container per-se, this is like the flat bed trailers or rail cars which carry goods too large to fit through end doorways and so are strapped down to a flat frame with two vertical end walls that fold down when not in use. Sometimes reinforcement bars lock into the upper corners of the end walls and often a tarp or light flat walls can be attached for protection, though there is no attempt to make them water-tight like the usual containers.
Containers come in two standard heights, 8' and 9' 'high cube', and two standard lengths, 20' and 40'. Enclosed 20' containers typically have one door in an end. 40' typically have two doors. However, variants of dual-door 20' and single-door 40' are not uncommon. In addition there is an infinite diversity of speciality containers fabricated on demand for special applications, though they rarely appear for sale used. These include such things as containers with side doors, containers of shorter and longer than standard lengths, half-height open-top containers used for bulk materials, interlocking short containers that lock together to form a larger standard containers, 'butter dish' containers that have an upper portion that seperates from a lower flat bed container, nesting containers that hold other cabinet-like containers inside them for fork-lift removal, and so on.
Containers first began being converted into housing to serve the needs of the oil industry which used the containers for prefabricated worker housing on oil rigs. The typical conversion approach used for this and many other similar applications has been to re-frame the interior of a standard dry shipping container with light gauge steel or wood framing in order to host conventional insulation, wiring, and wall board or pre-finished wall paneling as used in manufactured housing. Variations of the standard end doors with normal sized entry doors are often used and in order to frame windows, side doors, and roof-top ventilators or skylights despite the corrugations of the metal plate a wide flat metal plate is wleded into the opening. At sea, the normal 'foundation' used is 'king pin' mounts which are welded onto a ship or rig deck to lock the containers down at the corners.
More sophisticated adaptations began to appear when industrial users started looking to containers as transportable storage, labs, telecom centers, and offices. The 8' width of a container is very confining. Two 20' containers joined side-by-side to form a 16'x20' unit is a much more convenient basic room size. So various schemes were devised to join containers together, permanently or temporarily, so the intervening side walls could be removed to make larger rooms. The three most common approaches for this seem to be the use of a bolt-together raised seam (akin the the way raised seam metal roof panels work), permanent welded joint plates, and secondary roof coverings where either a membrane is placed over the containers to cover the seams between them or a completely separate metal roof is placed on top of them. These combinations inspired many companies -though for some unknown reason none in the US- to start making joinable container module buildings for a variety of applications. The Erge Corporation of Germany is one of the better known makers of these kinds of container buildings systems.
On land containers are often used with no more foundation than a flat spot of ground or a bed of gravel but more permanent installations use concrete corner pads, concrete piers, reinforced concrete beams, or a shallow perimeter foundation akin to that of a conventional house. Sometimes even slabs are used, though this can be redundant unless one wishes to cast a concrete floor within the open bottoms of the dry containers. Heavy steel king pins or bolts are formed in place in these foundations to lock the containers down at the corners, though sometimes this is omitted if the foundation pieces are wide enough.
Inspired by the poor of the Third World who frequently modify discarded containers into make-shift housing, by their inherent modularity, and by the glut of containers in countries with high import volumes, many architects have experimented with containers for modular housing concepts. These range from fairly simple but clever shelters that revel in their small size and extremely space efficient interior designs to very elaborate structures that join numerous containers in odd ways or integrate them with mechanical contraptions resulting in very expensive structures. One of the best -in this author's opinion- of the current architect-designed container homes is a prefab home product called Quik House designed by Adam Kalkin of NJ. This is a fairly simple container combination based on 40' modules but produces a spacious home and is particularly interesting because the designer claims to be able to optionally provide these with an entirely non-toxic composition. However, this comes with a minimum $160,000 price tag. Most people tend to think of the container house as economical shelter but when architects get involved this is rarely the case, though the Quick House is quite modestly priced compared the the majority. A cheaper but also much smaller supposedly non-toxic container shelter called the Chuckhouseis offered by the Global Portable Buildings company. Their literature suggests awareness of the need for a non-toxic interior but some of their choices of interior materials are questionable. This author has never been able to confirm their claim or get materials details out of them.
Having done extensive study of the many ways containers have been adapted to housing, this author has found that the biggest problem in using containers for housing is the cost and difficulty of getting the metalworking services needed in the US. In the Third World its easy enough to find people to hack containers into any desired form for next to nothing and in those countries one sees containers, and parts of containers, repurposed to an endless variety of uses. Here in the US, however, everything one might want to do with containers is a Big Deal because of the limited experience of metalworkers compared to their Third World counterparts and a fixation of companies on a specialist industrial market. Though there are some specialist companies here that do some sophisticated container modification work and routinely make container housing for the oil industry, the application of housing on land is always considered unusual -if not bizarre- here despite the ubiquity of container housing in most of the rest of the world. And these companies are used to dealing exclusively with corporations whose executives are notoriously dim-witted about value, want everything 'yesterday', and will casualy accept any price. And so exorbitant fees are demanded for the simplest container modifications.
Unless one can perform the modifications oneself or afford one of these ready-made products a container home may be impractical here. But whether hiring the work or performing it oneself, the key to practicality seems to be the use of the container with as few physical modifications as possible. This means trying to make use of the simple 8' wide unit as a single room with few changes and with the end doorways used for windows and portals rather than the sides as framing can be retrofit there rather than mounted in custom-cut openings. Containers with dual-doors are obviously better in this respect.
Using containers in this way, it is obviously easier to design homes using a compound approach, though this limits the home to mild climate areas unless some other kind of 'skybreak' shelter structure, like a tension roof system, is used to enclose the compound. A custom coupler made of structural steel profile or recycled container frames and used to connect the containers in a star pattern or a commercial solarium product used as a front corridor for a linear group of containers might also be cheaper than joining containers side-to-side while eliminating the climate issue with open-air compounds. But it would be difficult to make a perfect seal between these and the containers so there may always be an issue of weather and insect infiltration.
Some designs have made good use of plastic membranes to seal container combinations together. The same types of materials used for moisture barriers in compound roofing systems, these are finished in the same way and effectively create a second roof over the containers. But there is still the issue of the seams at the container end and bottom to deal with by other means.
The insulated containers are by far the easiest to modify and best suited to non-toxic housing because the sandwich panel material used in their walls easily accepts the use of clamp-fit windows and doors as used on boats and in recreational vehicles. The material is also suited to the use of rivkels -rivet screw sockets- which allow for the screw mounting of paneling and fittings while retaining demountability. Of course, the stainless steel interior is ideal for the non-toxic shelter and allows covering and fixtures to be attached by magnets as well. But, unless bought new and unpainted, one must still strip and replace all exterior paints with non-toxic alternatives -a job most people who need non-toxic housing would not be able to do themselves.
While there remains great potential in the container housing concept, the labor/cost problems of their use in the US makes them less cost-effective than other types of structure unless one has the means to do all the adaptation work through sweat equity. Since that work can involve paint stripping and welding, it probably precludes the option of sweat equity for the MCS patient while the high cost of hired labor or ready made units may preclude the use of containers altogether.
An extensive listing of container housing projects can be seen at the Container Bay section of the Fab Prefab web site.
Steel Prefab - The Industrial Shelter
Another type of construction popular with Modernist designers, steel prefab structures -though almost never designed for housing originally- have frequently been adapted into a vast assortment of novel housing.
The most well known of these is the steel arch which originally appeared for agricultural uses and for aircraft hangars, was turned into dormatory style housing on innumerable military bases and industrial facilities, and then started being qidely sold for garage and similar out-building structures for the general consumer. Steel arches are very simply constructed, consisting of a series of nesting corrugated galavanized steel panels that are bolted together and lifted atop a concrete slab or rail foundation. Steel arches present severe design restrictions due to their curved two-ended shape but compensate for that by offering large clear spans. They have been easily converted into attractive homes by the use of sprayed foam insulation and simple commercial glazing systems or conventional light framing to close the ends. Some can be earth bermed. Steel arch could offer some of the lowest cost and quickest built housing possible but in recent years this potential has been stymied by their manufacturers' peculiar methods of hard-sell marketing which have driven away most creative users of the products by making legitimate pricing and technical information impossible to obtain.
Because they are composed of galvanized steel, steel arches offer good potential for non-toxic housing and could be one of the cheapest types possible. Combined with isocyanaurate or Airkrete foam insulation, earth berming, commercial window-wall end enclosure, radiant heating in the concrete slab floor, and the use of simple open-plan designs they are practically ideal for this if one can get over their shape. But the marketing practices of their manufactures seems to preclude this. It is simply too much trouble to deal with these companies today and that is preventing the construction of a lot of novel homes.
homes from prefab steel barns - American Outback Buildings
Next most common among the steel prefabs is the great variety of frame and panel box buildings. These consist of simple large span steel frame structures using various forms of trusses, 'red iron' framing, structural steel profiles, and light gauge steel framing which are enclosed in modular metal wall and roof panel. Some have pitched roofing in shed or shallow gable forms, some nearly flat roofs. Most all of them use slab foundations. Originally designed for quick-built agricultural and industrial buildings, these have also found their uses for housing and a few manufacturers actually offer building packages designed for that purpose. Housing adaptation is straightforward, usually relying on the light re-framing of the interior in order to host conventional insulation and wall board products. Once finished in this way, interiors are indestinguishable from conventional homes. The many barn-like designs are especially well suited to housing. Though marketing from some manufacturers are as troublesome as that of the arch makers, sales people are typically much more knowledgeable about their products and less averse to the notion of housing uses and so these buildings have seen much more use in housing recently than arches have.
Adaptation of these for non-toxic housing is not difficult but a little more care is required than for typical housing adaptations. Not all the manufacturers use non-toxic primer paints or galvanized coatings on the metal work so one must first be sure that the basic structure is truly inert. Galavanized components are preferred, though the colored exterior coatings of roof and wall panels are usually baked-on coatings which are typically very inert. Interior finishing requires the use of alternative non-toxic wall board or paneling products, as does any interior partition framing. Some of these products offer insulation based on metalized polyethylene foam sheet which should be well tolerated by many MCS patients. Since the materials are impermeable, active ventilation is a necessity unless in mild climates and with structures using open plan design and large opening windows offering good cross ventilation. The modular windows typically offered with these building packages are often not adequate for some housing applications and often feature vinyl frames isntead of the more intert aluminum. Commercial windows products are usually easily adapted to these, given that the structural framing accommodates it. Often standardized garage door openings make for effective window-wall placements.
assorted steel park shelter forms - Poligon
The third kind of prefab steel structure suitable for housing adaptation is the pre-fab park shelters. These are simple open-side pavilion structures used in parks to shelter picnic tables or as gazebos and sometimes are host to various concession stands and service kiosks. They are typically based on a structural steel profile frame mounted on piers and supporting a metal panel or wood roof. Though these have rarely been used for this to date, their potential is great. They offer very attractive designs with large spans which can be simply converted into pavilion style housing simply by building them atop a slab foundation and enclosing them in commercial window-wall glasing and/or in-fill wall construction of most any material. They are suited to uniform free-standing buildings, sprawling structures, and 'compound' designs where individual rooms are contained in individual smaller buildings with open-air or enclosed pathways between them. hey are not well suited to multi-storey structures except where a free-standing mezzanine structure is used to host upper floors.
For non-toxic housing, adaptation is no different. The only caveat is that one must be sure the shelter structure is finished with non-toxic coatings. A few companies offer galvanized steel or baked enamel frames but most are simply painted. Since these structures favor pavilion designs, there is little finishing required. If a window wall enclosure is used, one need only deal with the floor and drop-ceiling coverings and complete the finishing with free-standing furnishings. This is one of the great virtues of the pavilion architecture approach when it comes to non-toxic housing, though not everyone is comfortable with a very-open-plan design. It is certainly not suited to closely grouped housing, but most MCS patients will seek edge-of-wilderness locations anyway where these are aesthetically ideal.
a modular mezzanine system
The fourth type of prefab steel structure suited to possible housing adaptation is the industrial mezzanine. Though rarely used in housing, industrial mezzanines are very similar to the park shelters in structure and can be used similarly for both single-storey pavilion style structures and multi-storey structures using commercial curtain wall systems as used in heavy steel frame structures. This includes non-toxic housing as well, though there is more ignorance about paints in this community of manufacturers and galvanized steel, though available, is much rarer. Some have great potential as modular building systems, featuring standardized bolt-together modular components which can be combined in endless variety, although limited to box shapes. The key difference with therse is that they have no roof. They are designed for use inside other large clear span buildings. But they can readily accommodate either compound flat roofing or metal panel roofing. Why these have so rarely been used for housing is a mystery considering their great potential. It may have to do with the lack of cooperation from manufacturers who simply have no concept of these being used for anything other than the one application they were originally intended for.
Heavy Steel Framing - The Residential Skyscraper
Heavy steel framing -or 'red iron' as it is sometimes called- has only rarely been employed in residential construction, with the exception of its use in the commercial-style construction used to build very large apartment complexes. But it has often been a favorite of Modernist designers who have sometimes employed such sophisticated custom craftsmanship in the fabrication of frames for visual effect that it has rivaled that of traditional wood post & beam construction -and often radically increased cost as well.
The use of heavy steel framing in homes is done with essentialy the same construction techniques employed in commercial construction, just with different designs that produce more comfortable habitats. The structures are built in essentially the same way as a skyscraper, using a post & beam or 'ramen frame' arrangement with posts set on foundation piers -sometimes integrated into a slab or basement wall systems- that relies on the massive and high strength nature of the frame components to allow for large spans and tall structures. Concrete sub-flooring -and sometimes sub-roofing- is the norm using corrugated steel plate decking to support the concrete pours and with the option to integrate radiant heating and electrical/plumbing conduits. A curtain wall system and often large expanses of glass are then used for enclosure along with compound roofing or metal panel roofing. Interior partitions are typically framed in light lumber or light steel with conventional sheetrock paneling.
There is much potential in this building technology for non-toxic housing but it has almost never been explored. Structures can be built quickly, rely on open-plan designs thanks to large spans, and in Modernist designs often make extensive use of inert materialsd for finishing and enclosure such as glass, metal panel products, ceramic panels, tile, and stone. The chief caveat of using this material is that the otherwise ideally non-toxic steel can be made toxic if the primer coatings applied to it are composed of toxic paints. Some are, some aren't, and you will almost never find a supplier in the US who knows the difference. There are no boilerplate plans for homes based on this kind of construction and the huge heavy components typically require heavy machinery to handle. They are almost always archiect-designed and built using commercial rather than residential contractors. Thus the use of this approach may not be practical from a sweat-equity standpoint. But the potential is great, especially for homes based on this author's favorite type of pavilion architecture.
Saturday, June 11, 2005
Light Steel Framing - Cold-Rolled Shelter
Originally used chiefly for the non-load-bearing portions of commercial construction, light gauge steel framing has become increasingly popular in conventional housing in the past two decades and, since such homes are often indistinguishable from wood frame homes due to the structure being hidden under sheet-rock paneling, many home owners are completely unaware that there is actually steel behind their walls rather than wood. At one time much more expensive than lumber framing, rising lumber costs have made steel cost-competitive. Rapidly fluctuating steel prices in recent years, however, have forced manufacturers to provide pricing on an almost daily basis rather than use standardized pricing.
Typical commercial steel construction is charactized by the use of heavy steel beams -the so-called 'red iron' steel framing named for the once typically reddish colored primer coatings sprayed on it. Light gauge steel framing is based on the use of thin galvanized steel sheet formed in a stamping and cold-rolling process into roughly 'C' chaped channels which, like the pressed steel bodies of automobiles, rely on their corrugations and folded shape for rigidity and compression strength. Used very similarly in terms of construction method to stick-built wood framing, light steel framing is assembled using self-embedding screws rather than nails, the flexibility of the metal allowing the steel channels to nest against each other or to be easily cut and folded to form attachment flanges allowing the screws to the driven through the layered sheet metal for attachment. A crimping tool is also used to attach framing members rather than screws where framing is not load-bearing so as to create a flatter surface for attaching wall board. Though dimensions are similar to lumber, light steel framing is offered in a variety of gauge thicknesses so as to allow building engineers to employ the least amount of metal for necessary strength. The contractor or designer for a steel frame home must thus be a little more careful in the calculation of loads in order to prevent unecessary costs. There are also a number of specialty channels offered which simplify the attachment of finishing products and infrastructure components to the framing.
A number of successful non-toxic homes have been built using light steel framing, exploiting the inherently non-toxic composition of the material and combining it with the less toxic alternative finishing materials. But there is an important caveat to consider when using this for such housing. The steel channels sometimes come from the manufacturer with a machine oil coating still on them. This is sometimes a residue of manufacture and other times is actually added by manufacturers as bonus corrosion prevention -though it's rather redundant for galvanized steel if it is of nominal quality to begin with. This oil is toxic, odorous, and can seep into sheet rock paneling and should be washed off, ideally using a non-toxic non-residue detergent like trisodium phosphate (TSP) This washing can add significant labor overhead to the cost of a home -especially if the need for it is unexpected. In some cases costs of homes have been doubled by this. But there are also low-toxic home designers who claim that this oil is very quickly evaporated and poses a minimal problem. For the average home this may be true. For those already with environmental illness and very sensitive, the washing is probably necessary. Thus the cost of this type of framing can become very expensive even if the material cost is the same as lumber.
Light steel framing is also often offered in packages which can greatly reduce their cost. But since these homes are in no way designed to be non-toxic, it would take experienced builders or non-toxic housing contractors to make sure they can be effectively adapted to this purpose.
Note that there is an extruded aluminum alternative to light steel framing alled Aluma-Strut which is offered by a Texas based firm of the same name. Aluminum has some potential advantages over galvanized steel in that it is non-magnetic and so may be more suitable for individuals with EMF sensitivities, never has an oil coating which might need to be removed, and is recyclable with much less energy than steel making it slightly more environmentally friendly. This particular aluminum framing is used in a similar manner to light gauge steel but relies on bolt-together assembly using specialized connectors which also offers the bonus advantage of potential demountability.
Unfortunately, the Aluma-Strut product is based on a proprietary profile and connector design with this one company the only source for it in the world. The company does not sell components by themselves, only housing packages which they will custom engineer to order for any architect's design submitted. This seems to be an astounding business blunder since the need for repair and expansion is common for all housing and this firm seems to have no plan for addressing that. Any contractor asked to work on a home made with this will do is scratch his head in bewilderment. The company web site also seems to be having some difficulty of late and may automatically send users to a dead page. Not sure what this implies for the health of the company, though they have definitely built structures in the past so it is a proven product, to some degree.
A similar custom aluminum profile based product is the Modular Housing System of US Systems. MHS is a very sophisticated building system that originated in a product designed for store display and kiosk construction and has many similarities to the later discussed T-slot framing technology. Again, used similarly to light gauge steel in framing design, it uses a proprietary connector system with a key-bolt lock mechanism that makes for very rapid assembly and uses modular panels which integrate in-line with the grooved shapes of the frame profiles. This allows for simpler frame systems as the panels share in the structural strength, though even without them the system is much more rigid than light steel framing and can work in post & beam designs. Panel materials are made of conventional SIP materials but the company had great interest in the potential of the non-toxic housing market and the system is able to accommodate alternative materials. This system was extensively researched and strongly considered for this author's own non-toxic housing needs.
US Systems is a bit wiser in that it has offered its building components separately from the housing packages it also offers and is willing to perform package engineering to order. Unfortunately, the company has yet to actually ship product. They have encountered much difficulty in finding American aluminum extrusion companies sophisticated enough to fabricate profiles of such large size and complexity. It's yet another one of the many industrial areas this country has ceded superiority to the rest of the globe. So it remains unclear when this potentially powerful building product will actually become available.
Saturday, June 4, 2005
Wood Framing - Alternatives In The Conventional
This web site has generally projected a negative opinion of conventional wood frame construction, particularly in terms of its increasingly doubtful indoor environmental safety. But the fact remains that wood is one of the most popular of natural building materials and is ideally suited to the non-toxic home WHEN IT CAN BE FOUND IN AN UNADULTERATED FORM and when using non-aromatic hardwood species. That, of course, is the key problem. It is because lumber is so ubiquitous in conventional construction and so relatively uniform in nature that companies have so often sought to 'improve' it by chemical means as a means to capture market share and especially to try and compensate for its steadily declining quality. As our natural forest reserves have dwindled and the lumber industry turned to younger and younger trees for material the quality of typical lumber has slowly but steadily deteriorated, drawing lumber producers to the use of chemicals to compensate. As lumber has become more expensive, more and more of the tree must be put to effective use, compelling the 'engineering' of lumber products by gluing together what were formerly unused waste materials. The contemporary wood framed home is, in fact, evolving into a structure made primarily of a kind of high-tech papier-mache and ultimately into a kind of plastic composite as the need to use cruder lumber with greater efficiency grows. You simply don't get any more efficient in the use of lumber content than by reducing it to its raw cellulose content and turning it into plastic parts with a faux-wood finish! People thought the plastic demonstration houses shown at exposiions in the 1950s and 60s were fanciful at best. But in reality, this is exactly what the contemporary house is evolving toward.
But where natural unadulterated lumber is still available and affordable and the knowledge of traditional wood craftsmanship at-hand, wood frame construction is perfectly suited to non-toxic housing. The key is to ferret out and eliminate the innumerable toxics industry has snuck into the lumber products spectrum, and that takes some diligence. The first place to start is in the sourcing of lumber. There are organic tree farms as well as dealers in 'recovered' lumber (lumber from pre-20th century post and beam buildings and from pre-20th century logs recovered by divers from the bottoms of lakes and rivers) who can provide chemically unadulterated lumber. There are also some species of tree whose wood is so impermeable that chemical treatment is almost impossible. Indonesian ironwood is a good example and is the basis of one of only a few non-toxic kit home products available anywhere in the world; the Bali-T House by Tony's T-Houses.
Tony's Bali-T, Double-T model on site in Bali
Another issue, at least for those already suffering from environmental illness, is the terpenes naturally produced by armoatic softwoods like pine which, because they are cheap, are the most commonly used for construction. Many toxic sensitive individuals cannot tolerate the outgassing of these terpenes even if they are natural and so must rely on harder non-armatic wood species like poplar, beech, birch, and maple. This lumber is harder to find and more expensive, but also more durable and insect resistant.
For the rest of the home, there are currently non-toxic alternatives to most 'conventional' toxic materials used in the conventional wood framed home. But they take some research to track down and are often more expensive. Lisitng them all is beyond the scope of this short article but there are now a growing number of books available dealing in this subject and which offer their own catalogs of sources. The Materials and Products sections of this web site will also list many such materials as they appear on the market.
While even the most conventional of stick frame housing approaches can be adapted to non-toxic materials, the higher cost of using chemical-free lumber and finishing products does call for a greater efficiency in home design and construction method in order to bring costs down to a reasonable scale. This favors the use of more contemporary designs and building methods such as modular post and beam construction. Most people are familiar with post and beam construction in barns and in the rustic style architecture inspired by them. Modular post and beam construction is quite similar except that it relies on a pre-engineering of structure and designs that use a fairly small set of simple standardized components. It may also employ the use of modular steel joint systems which effectively allow the lumber components to be used in the manner of a commercial steel framing system. A good example is the Volkhaus framing system developed in Japan. (for info see; Landship, Be-haus, A-Kit, and the Oji-Group) Though still rare in the US, such modular post and beam systems are becoming increasingly common in the rest of the world and may soon emerge here.
Volkshaus system - Landship and Be-haus
The chief advantage of modular post and beam construction in terms of the non-toxic home is in its ability to provide large span areas and separate finish structure from primary structure. This is a key virtue of the 'pavilion' style of architecture this author has elsewhere written extensively about as the basis of non-toxic housing. The key to economizing on the interior of the non-toxic home is the reduction of materials and surfaces that need special finishes applied to them or which need special custom crafting to interface to the structure of the home. A clear-span structure leaves most interior finishing to retrofit elements and what may be considered discrete self-standing pieces of furniture. Thus it becomes possible to use finishing materials that normally wouldn't be compatible with conventional construction and minimize or eliminate the need for things like paints and adhesives. Modular components can also be prefabricated far from the intended building site and can be assembled with less skill than normally required. It really doesn't make a whole lot of sense for wood frame construction to still be relying on things like nails and screws when quality lumber is such a precious commodity and mechanical interfacting is just as versatile while offering the virtue of demountability without demolition. Homes are renovated with ever-increasing frequency today. Why are they still not designed to make that easier and less wasteful?
Kure-Tec joint system
As a non-toxic building material natural wood has perhaps the best spectrum of qualities next to earth. Unfortunately, getting conventional contractors to prescribe to non-toxic standards is difficult and the diligent sleuthing required to find affordable non-toxic alternatives to conventional building and finishing products is often too much for the average individual. So it is often easier just to go with the more alternative construction methods than to try and adapt the conventional frame home to the non-toxic standard. However, it is a fact that the fully non-toxic ironwood based Bali-T kit home does actualy represent one of the lowest cost non-toxic housing options available. This well illustrates the potential in a modular post and beam approach. Unfortunately, its particular design makes it suited to only the mildest of climates.
Fieldstone Masonry - The Modern Stone-Age
Though more familiar among the foundations of 19th century homes and the decorative fireplaces of more contemporary homes, fieldstone masonry construction has often been used for complete buildings, though more commonly used for aesthetic effect than for any practical reasons. Deriving from techniques going back to neolithic times, contemporary fieldstone masonry construction companions stone to concrete as a means of simplifying ans speeding an otherwise very labor intensive construction process. Though based on a natural material, fieldstone masonry is not usually considered in the repertoire of sustainable construction because fieldstone itself is not a renewable resource. It was common in early times because of the large numbers of stones farmers would remove from fields they were clearing for farming -hence the name and the common use of this material in early farm housing. But today it has become one of the most costly building materials available.
There are a great variety of stone masonry techniques but the two most commonly seen used for whole house construction are based on either the careful laying and mortaring of stones in the manner of brick-laying or slip-formed methods where stone is stacked within forms and then filled with concrete. All the types of foundation, roofing, and flooring systems common to concrete can be used with this. Earlier construction methods sometimes employed a double-wall approach creating a gap in the stone walls which served as insulation. In more modern versions this would be filled with insulation material -ideally something well compatible with the stone such as mineral foams like Airkrete. This approach allws the stone wall to serve as both exterior and interior wall with little additional finishing -assuming one likes the rough stone look. More commonly, though, insulation is accommodated by framing-out the interior to support finishing by typical wall board, traditional lathe and plaster, and -in the European estate tradition- crafted wood paneling systems.
Though considered primitivist or associated with the architecture of Medieval times, fieldstone masonry has often featured in contemporary or Modernist architecture, though usually in an accent role rather than as a primary structure. In some cases, though, designs based on massive minimalist primary stone structures are used, often interpenetrating other structure or providing a kind of exposed superstructure to which the rest of a building is in some way retrofit.
Because it is a naturally non-toxic material, fieldstone masonry is well suited to non-toxic housing construction. But the extremely high cost of this type of construction generally rules it out for the vast majority of homeowners.
Straw Bale - Home From The Farm
Originating on the plains of the American Midwest, star bale home construction is considered one of the few truly indigenous American vernacular building technologies. The product of necessity, it arose from frontier farmers' need to shelter themselves in a location devoid of the forests that normally provided lumber. Eventually obsolesced by the introduction of cheaper import lumber made available by rail transport, the technology enjoyed a revival in the 1970s and 80s as a sustainable building method and remains popular among green architecture enthusiasts around the world to this day.
As a building material, straw bales have the three virtues of being the product of agricultural waste -which is what makes such housing sustainable- offer a high insulation value, and come in large simple to manage blocks. Some consider it a superior building material to earth in terms of its insulation and ease of handling but it lacks the thermal mass of earth, even though it does have much better thermal mass than frame construction. It is often a superior choice to earth for cold weather climates and has done well in the Winter extremes of Canada.
Straw bale is used in two basic building methods. In the traditional load-bearing wall form, it is used much as adobe is. Bales are stacked up like large bricks upon a rammed earth, field stone, concrete and stone, or concrete foundation to form thick walls. The bales are pinned together with long vertical pins made of rebar or the like. Door and window frames are similarly secured with wooden dowels. A threaded rod pin method is also often used for the traditional load-bearing style of structure, threaded rods coming from foundation to a wooden sill-plate attached with nuts and tieing the wall to the foundation mechanically. A lathing mesh of wire or polymer is then applied and the wall surfaced finished with a thick adobe plaster. The end result is quite similar in appearance to adobe construction except that the flat composite roofing of 'pueblo style' architecture is replaced by a shed, gable, or hip roof supported by simple beams pegged into place on the bale walls or more elaborate truss roofing. Metal arch roof has sometimes been used to nice effect. A broad roof overhang and high foundation clearance are usually desired as a protection against water infiltration -much as with cob construction.
The other method for straw bale construction treats the bales strictly as an in-fill wall material for a structure based on steel or wood bost and beam construction. The frame is an indepenent structure which the straw bales are stacked around and within in their usual way, sometimes with pegs to interface them to the frame structure. This allows for much larger span spaces and more storey height but it actually developed because of the reluctance of many communities to accept the use of straw bale. Mistakenly believing straw bale to be too weak for safe construction, many building inspectors refused to accept straw bale structures unless they had another more conventional superstructure. In the places where this has become standard building code for straw bale, virtually all cost benefits of this construction method are lost due to the added expense of this redundant superstructure. This has not, however, impacted its popularity with sustainable building enthusiasts even though it does insure that what was originally a low cost building method no longer is.
Though very similar in appearance to earthen construction, straw bale is not quite as versatile due to the form and dimensional limits imposed by the large bale block shapes. But it does allow for some sculpturing of details and is a much quicker building method for simple shaped structures.
Straw bale construction is somewhat intercompatible with other earthen construction methods, allowing for hybridization to compensate for its limitations.
As a non-toxic building method, straw bale is very popular with those seeking 'natural' or 'organic' building materials. But how safe it is depends on a couple of things. Straw will retain pesticide and chemical fertilizer residue so unless the straw originated with a certified organic farm one cannot be sure how clean it really is. Such straw bales will obviously not be as cheap as others. Also, while mold is not considered a problem for such construction when properly performed and maintained, poor construction, design, or delayed maintenance can result in mold and pest infiltration. Straw itself is an allergen for some people and that should be tested before committing to its use. These caveats aside, this can be a good choice for low toxic housing. Only contractors specializing in sustainable construction typically work with it but because it has become something of a fad among green building enthusiasts there are numerous class programs training the public in the building technique -perhaps more than for any other sustainable building method.
An excellent source of links with additional info can be found on the Surfin' StrawBale web site.
Another good site offering an excellent series of modest sized straw bale home plans can be found at Balewatch.
Tuesday, May 17, 2005
Pumice-crete - How Volcanos Make A Non-Toxic Home
Pumice -the porous stone made famous by Lava brand soap and notable for its ability to float in water- is a low density basalt produced by volcanoes and is commonly found in most of the world. Related to it are vermiculite -well known to landscapers and gardeners- and zeolite, a form of pumice with the ability to absorb and hold organic molecules and often used in air purifying devices. When combined with common cement mixes pumice produces a soft pourable concrete with much of normal concrete's strength and some very valuable properties. It is self-insulating as it has a foam-like structure and, like zeolite, it retains some ability to absorb and trap organic pollutants. Its rough surface easily takes on any typical plaster, stucco, or adobe finishes and is soft enough to be craved into detail shapes or have channels cut to accommodate utilities conduits. Though commonly used in a variety of supplemental roles in concrete construction, it is recently begun being used as an alternative to adobe for pueblo-style construction and -at least in the US- has become the single-most popular material for housing MCS patients.
Pumice-crete is typically employed with slip-form construction methods commonly used for reinforced concrete construction. However, it is not as strong as conventional concrete and must be employed in thicker walls appromating those of adobe construction. it can be used for roofing; poured over forms, structural beam supports, or made into planks sealed with a thin pour. Typical pumice-crete construction employs pueblo or Mediterranean style design and their contemporary variations, comonly employing viga, rustic beam, or truss supported compound roofing. But it generally has the same potential design freedom as any form of concrete and is foten combined with ferro-cement techniques.
For non-toxic housing it's only disadvantage is a reduced hygroscopicity -though it is better than concrete for this. However, it makes up for this quite well by being cheap, offering better thermal performance than adobe or compressed earth block, much lower labor overhead than either of them, and having some modest ability to actually clean the air inside the home. In fact, some homes have deliberately used zeolite instead of pumice just to maximize this, though zeolite is much rarer and more expensive. Pumice is commonly available in many parts of the US but in others it can be too expensive to import and in those cases foamed concrete may be a better choice. Foamed concretes have many of the same properties and -as long as they use non-toxic foaming agents- are about as good. But some types of foamed concrete -such as Ytong concrete- can only be pre-fabricated in gigantic autoclaves and so are only available as component systems usually limited to trial applications.
Ferro-Cement Construction - From the Industrial to the Fantastic
Invented in the early 20th century, the technique of ferro-cement construction became the basis for some of the most famous architectural works of that century, most notable among them being the fluid organic designs of Antonio Gaudi. A simple but infinitely versatile technique, ferro-cement is based on the use of wire mesh reinforcement to which a fine grained aggregate mix of concrete is applied by hand, trowel, or spray device to form a hard but potentially thin and strong shell. Used both for sculpture and for construction, the technique very often blends the two in fanciful design typified by the free-form organic design movement inspired by the works of the likes of Gaudi. It is a very popular building technique for the more creative DIY home builder and for many Modernist and Post-Modernist designers. It is also a very common building method in countries such as Mexico and in South America and the Caribbean.
As previusly noted, the basic method involves the application of a fine concrete to a wire mesh reinforcement structure. This can be enhanced by incorporating a plastic, foamed cement, or pumice-crete core to the shell structure. A number of pre-made mesh panel products are available such as ICS 3D Panel, Monolithic Panel, and Tridi-Panel. These feature an already installed foam core panel and easy wire-up assembly, saving a great deal of labor. They particularly good for foundation work, simple columns, roofing, and for simple more rectilinear structures. They cannot be bent into very complex shapes or tight curves and so serve better for larger area structural features in true free-form designs, working well in combination with finer mesh for more intricate detail.
Ferro-cement homes are typically based on shell designs using domes, vaults, or complex free-form shapes usually featuring clusters of single-room-per-shell structures or very large area roof shell forms partitioned internally by retrofit structure. Ferro-cement structures can be earth bermed, made underground, or even made to float on water -the same technique having long been used to make hulls for yachts. Labor needs are low, a handful of people being able to produce large structures with few tools -albeit still quite labor and time intensive and demanding a certain artistic talent to produce clean elegant finished. But its greatest attraction lay in the almost unlimited freedom of form possible with these structures and the fantastic fluid forms skilled artists and designers have produced using this.
Finishing work is usually pretty simple and based on simple plaster and stucco finishes or more elaborate combinations of pebble, tile, and sometimes painted finishes. Elastomeric paint is sometimes used for roof surfaces and even the plastic used with pick-up truck bed liners has been applied for truly indestructible exterior finishes. It is common to incorporate a great deal of furniture and fixture elements directly into the forms of the more organic designs, which saves money on furniture but requires more skilled design and present the complication that such features cannot be later changed without selective demolition.
As the basis of non-toxic housing, ferro-cement is a good choice. It's economical, its materials are naturally non-toxic, and its potential for owner-builder construction high. But it is not a hygroscopic material and care must be taken in the ventilation of structures to prevent humidity problems. Also, it's great freedom of form can lead the inexperienced to make costly or dangerous engineering mistakes. Without the support of very talented designers and artists, it is as easy to produce a very ugly looking structure as it is to produce an elegant one, unless one sticks to very simple designs. It is hand-labor intensive, being essentially a sculptural construction process, and there are no readily available contractors for this kind of construction work in the US, even though it has a very large DIY builder following here.
A popular concrete dome home system known as Monolithic Domes uses an interesting pneumatic form variation of the standard ferro-cement techniques. The inflatable dome form is used to support foam and mesh before final cement application and then remains as a protective exterior covering. A similar system design by architect Dante Bini called Mini-Shell may offer an even more efficient alternative. This system deploys its pneumatic form flat and deflated with the rectangular reinforcement mesh placed on top and the cement poured whole over it. After a short partial curing period, the form is inflated under the concrete lifting it into a square-based dome with two or four open arch portals on its side which can be enclosed in windows. Once the shell has set the form can be deflated and moved to make additional shells adjacent to the first, allowing for a spwawling modular structure. Alas, this clever system has only seen use in Europe and Australia and there is no source for it in the US.
Reinforced Concrete Construction - White Mans' Earth
There are several basic forms of reinforced concrete construction used in housing; slip-formed reinforced concrete, prefabricated mdular component systems, and ferro-cement. The oldest among these is probably slip-formed concrete which was employed for homes as far back as the late 19th century. Early in the 20th Century, Thomas Edison actually developed a slip-formed home building system which used huge steel molds to allow homes to be poured complete with Federalist style decorative features. Virually indestructible, a few of Edison's concrete homes can still be found in New Jersey. Later, Frank Lloyd Wright made extensive use of this in housing, devising novel techniques for its finishing including the casting-in-place of decorate stone and the use of hybrid systems based on modular textured tiles called Textile Blocks -a very promising technique that could be revived and improved today. But the use of this for housing really came into its own with the Modernist designers who have seemed to find a grace in this material most others have not.
Typical reinforced concrete construction begins with the erection of cages of steel bar reinforcement which are enclosed in wooden or -increasingly- modular steel forms which hold the wet concrete in place as it cures. All or major portions of a structure are cast at once in a more-or-less continuous pour of liquid concrete allowing for rapid construction. Foundation, walls, and sometimes even roofing can all be made at once.
Often -at least for housing applications- foam panel is applied to the concrete exterior surface for insulation or a foam or sometimes pumice core is cast in place within the concrete. This technique has evolved into a variety of 'insulated form systems' composed of modular plastic foam blocks such as the Rastra Block brand -though such systems are not advisable for non-toxic housing due to a reliance on toxic adhesives to bond the form blocks together.
Due to its very high strength and 'plastic' nature when poured, reinforced concrete is capable of an infinite variety of shapes and decorative styles. But, while ubiquitous for commercial, industrial, and municipal construction, it has had a hard time being embraced for general housing use despite its fairly good economy and exceptional durability. Americans especially have a cultural aversion to the material and for this reason much Modernist architecture has had a hard time being made here or surviving the test of time.
In recent years concrete has developed a somewhat undeserved negative reputation among environmentalists. Most likely a bias derived from their aversion to urban aesthetics where the material predominates, many environmentalists consider it non-sustainable due to the high energy overhead of its manufacture. In fact, all the materials used in concrete are naturally recycled -albeit rather slowly- and there is no reason one cannot use renewable energy to make it. Also, it is the primarily building material for underground homes -probably some of the best kind of housing one can make from an environmental standpoint. However, it's often been mis-used. The term 'white mans' earth' comes from how concrete was regarded by people in Third World countries where its use was imposed by international aid workers, especially in the 1960s. Thinking they were helping raise these countries to a western standard of living, they advocated concrete as a superior alternative to the earthen materials commonly used in indigenous vernacular architecture. But concrete was not readily producable in many of these undeveloped countries so its use made them dependent upon an imported material, encouraging a western style cash economy and the social disruption that brought with it to indigenous cultures.
As a non-toxic building method and material, reinforced concrete is quite practical even though it is not a breathable hygroscopic material like earth or clay. This is often more than made-up for by its increaed strength, it's ability to easily support underground or earth-bermed construction allowing the exploitation of earth thermal mass, and its ubiquitous availability. But because of the common aversion to this material on aesthetic grounds, it is most often completely covered and disguised by other finishing materials supported by the same old light lumber and steel framing of conventinal housing. Affordable non-toxic housing with this material requires embracing its appearance and feel and leaving it unadulterated or simply covered in simple plasters and stucco, hence it tends to work better in concert with Modernist designs.
Modular Ceramic Component Systems - Fireproof Prefab
Almost entirely exclusive to Japan and perhaps to only one or two manufacturers there, modular ceramic component systems have been touted as one of the most sophisticated building technologies at present. The concept builds on mid-century Modernist ideas of modular component housing based on single or multi-room cellular modules prefabricated of concrete and which plug together into nesting complexes to form complete homes. The epitome if this ides is illustrated by Montreal's famous Habitat 67 apartment building, designed by Moshe Safdi and built for the Montreal Expo. A design for a similar system called Habitat Puerto Rico was long on exhibit in model form at Disneyworld's EPCOT Center.
Though the concept saw little use in Western countries -except for municipal/insititutional construction- after the 1970s, in Japan a great many experiments with wuch structures were done. But there too it was generally abandoned for large building only to re-emerge in the form of a system for prefabricated suburban housing. Notorious for the density of habitation, Japan has long had a serious problem with home fires (though, truth be known, the US may have the highest incidence of home fires in the world) and the usual materials and structures with which typical factory-built housing are made are not particularly fire-proof nor earthquake resistant. Thus was devised the notion of factory fabricating large component home modules from solid steel reinforced ceramic and pre-fitting them with utilities, interior/exterior finishes, and built-in fixtures and furnishings. These modules are formed in large steel molds in a factory, fired in huge kilns, outfitted to order on an assembly line, then shipped out on large trucks where they are assembled with cranes, fitted and bolted together, and their module-to-module interconnects linked. Using this system homes widely varying size and design could be assembled in a single day and a few large suburban housing developments were built with these systems. Designed to approximate what is now a standard western-style housing appearance in Japan, the ceramic modules could have their outer surfaced treated for a great variety of finished looks, simulating everything from brick to wood siding with coloring permanently fixed to the material.
Because of its ceramic composition, these building systems could be useful for non-toxic housing but, while they were indeed marketed as more 'hygienic', no particular attempt to exclude latantly toxic interior finishing materials has been made by the manufacturers. So it's an open question how practical these may be as non-toxic housing since such adaptation to exclusively non-toxic finishing materials and furnishings could only be possible with the manufacturers cooperation. Only a few demonstration homes using this system were ever made in the US and the current status of this technology remains unknown to this author.
Sunday, May 8, 2005
Extruded Clay Block Masony - The Industrial Adobe
With the costs of traditional brick masonry becoming untenable in the post-WWII world, many new alternatives to the traditional brick began to emerge in the construction industry. Concrete blocks became the most common but one of the most promising to emerge was the extruded clay block which has become common throughout Europe and the Middle East but which remains -oddly- virtually unknown in the US. Extruded clay blocks are just what their name implies; hollow multi-channel blocks of clay extruded from a machine like toothpaste from a tube and kiln fired to make a hard terra-cotta like material. In addition to blocks, it can be found in a variety of interlocking modular shapes including roofing, wall, and floor panels for both indoor and outdoor use. Loosely related to this are a number of interlocking extruded gysum panels and blocks used primarily for non-load-bearing interior wall applications as an alternative to drywall panels.
Though not as strong as traditional brick or concrete block, the extruded clay block offers some insulation and the breathability and hydroscopic properties of adobe blocks as well as a high precision shape with a diversity of modular forms and a variety of finishes. Their hollow spaces can also be filled with reinforced concrete to make stronger hybrid structures and they can easily accommodate utilities routing by cutting through an outer layer of channels and plastering over them. They they readily take a plaster or stucco finish but are often left unfinished at least on the exterior as the textured surfaces and warm terra-cotta colors are quite attractive as-is.
Used in roughly the same manner as concrete block masonry construction, extruded clay blocks have less compressive strength and so are usually used in a hybrid concrete-filled manner for multi-storey structures (select channels filled with rebar and poured concrete to form a grid of structural reinforcement inside the clay blocks) or as in-fill walls surrounding wooden or steel post and beam structures.
The breathability of the clay block is an increasingly desirable quality today with more health-conscious designers. The blocks provide good insulation while avoiding build-ups of humidity. Like a terra-cotta water jug which chills the water it holds by letting some soak through and evaporate, the permeability of the clay allows for a temperature moderating effect. This is an excellent choice of material for the non-toxic home -assuming one can find these block products and keep the rest of the interior made of non-toxic materials. While large apartment buldings and mass housing developments are built with these in Europe and the Middle East, in the US they seem to be rather rare so availability is a big problem here.
Block/Brick Masonry - Virtue in Urban Tradition
Cities from antiquity to the present have tended to favor masonry construction for the obvious reason that it resists the spread of fire. The very first cities were, of course, built of cob and adobe block and these were the mainstay of urban construction in our civilization until the invention of the fired brick and concrete which became the urban construction mainstays until the very recent emergence of the skyscraper with its heavy steel frame construction.
Fired bricks and concrete blocks were considered an improvement over adobe by virtue of their much higher compression strength, resistance to weathering, and their lack of need for surface finishing. Fired bricks and concrete blocks also had an advantage in terms of production. Their resilience allowed them to be stockpiled in large quantities in the open for indefinite periods of time and they could be transported great distances without damage. Brick offered all the virtues of stone but using materials which were cheaper and more ubiquitous than building grade stone, could be fashioned with less labor, and could be made just about anywhere. But all this came at the cost of breathability, hydroscopic qualities, and thermal mass for which adobe is famous as well as adding a high overhead in energy for their production. These drawbacks, however, seem to have been considered less important in places like the urban industrial regions of the northern hemisphere where traditions of fired brick and concrete use can sometimes be seen to go back even to Roman times. But by the post WWII period the use of fired brick, at least, began to wane worldwide as the cost for the specialized masonry labor steadily increased. Today new true brick construction is rare and expensive and most buildings that appear to have brick composition in fact only have a 'brick-face' facade formed of thin tiles. However, brick construction may be making a comeback in the future -not on Earth but elsewhere in our solar system. Brick construction is considered a logical approach for permanent habitat development on Mars -for the obvious reason that there will be no lumber industry there for quite some time.
Typical brick/block masonry construction is based on the simple laying of blocks with a cement bonding morter between them atop a brick/block or concrete foundation to form systems of load bearing walls and sometimes arches, vaults, and domes. Concrete blocks are often hollow forming an insulated space and a route for utilities conduits. Traditional brick is solid and walls are sometimes fashioned as double-walls with an insulating gap tied at intervals by metal pins for the same effect or, more often today, the interior is framed in wood to host insulation and conduits and finished in the manner of stick framing. Thanks to their high compressive strength, brick/block walls can be much thinner than adobe walls and host heavy timber or steel beams, concrete beams, trusses, or numerous short spaced floor joists in order to support structures of many storeys in height. These can be topped with any kind of roofing, though in the urban setting of the 20th century compound roofing became the most common allowing street-facing facades with elaborate details made by combining brick, stone, metal, and even glass block elements. This masonry technically needs no surface finishing except for appearance since it is quite weather-resistant. But glazed finishes or plaster covered surfaces as well as painted coverings are common.
Conventional brick and concrete block masonry are naturally non-toxic and so make a potentially good choice for the non-toxic home with the caveat that they are non-breathable non-hydroscopic materials. Unfortunately, high and skilled labor overhead make all but concrete block construction cost prohibitive and in the western world it is almost impossible to find contractors who can still build brick homes with traditional methods, using any other interior finishing but wood or light steel framed and sheet-rock covered interior walls. To be truly non-toxic, this kind of masonry construction needs to avoid the need for interior finishing or employ methods similar to that used with adobe or -at the very least- employ traditional lathe-supported plaster walls on certified safe lumber interior framing. The difficulties in doing that have made this a rare option for most non-toxic adapted housing.
One of the most promising concrete block building systems available at present is the DAC-ART Building System which is based on a very sophisticated pre-finished insulated core concrete block that simulates the appearance of natural stone blocks. DAC-ART blocks come in a variety of standard and custom shapes and finishes and go together with great simplicity producing Classical or Palladian inspired structures that need virtually no finishing after assembly. This is potentially very well suited to the employ of pavilion style structures which can link a very minimalist yet Classical looking structure to a Modernist interior design.
Tuesday, April 26, 2005
Earth Berm Construction - Under-Earth Without Being Underground
Usually employed as a variation of other building methods, earth berming affords the energy efficiency benefits of earthen construction to other types of structural materials and systems. More common in the traditional architecture of regions with extreme winter climates such as Scandinavia or the American plains region, earth berming has become popular with sustainable architecture advocates and owner-builders looking to get the benefits of earthen construction at a lower labor overhead.
Earth berming quite simply involves the piling up of earth on the sides and sometimes the roof of a structure to provide a thick surrounding thermal mass. This may be done by hand or by mechanized earth moving equipment. This is often enhanced further by a sod covering which protects the berm from erosion and makes it look more attractive. Berms may also be terraced and used as gardening space.
The structure enclosed can be of most any type but its exterior walls require some kind of water-proof covering and buried plastic membranes or pipe channels may also included in the berm itself to act as a means of diverting moisture away from the structure. Exterior insulation in the form of foam materials may also be added, as is common in underground home construction. Sometimes the enclosed structure may be built partially below grade, the excavated earth used in the construction of the berm. Windows tend to be few and small except on one exposed -usually south-facing- side exploiting passive solar heating. Some designs use an earth covered roof rather than a side berm, allowing for more windows and exits but requiring a structure of much greater load-bearing strength. Rustic post & beam, stacked log, stacked stone, steel arch, and ferro-cement shells are common with earth bermed structures today. In the past a great diversity of structures were earth bermed. The vikings would winter-over their long-boats by over-turning them and earth berming them to create a simple long-house, the approach later mimicked in permanent long-house designs.
For non-toxic housing earth berming affords no particular health benefit but does allow for greatly improved energy efficiency and thermal performance for other rather simple, cheap, and quickly built structures, particularly steel or ferro-cement shell structures. Thus one can gain some of the benefits of earthen construction without the massive labor overhead and high cost.
Wattle & Daub - East Meets West
Imagine any stereotypical 'traditional' street scene in Europe and what will likely come to mind is those curious closely-packed town-houses with exposed post & beam structure and a white-washed or buff-brown facade, sometimes criss-crossed by diagonal wooden beams. Though often faked for appearance, this is the hallmark of the traditional European building method known as wattle & daub. Thought to originate in the Neolithic period, wattle & daub was ubiquitous in Europe from Medieval times onward, declining in popularity with the growth in the use of fired brick. But the technique is not exclusive to Europe and has a direct independently invented counterpart in Asia which in Japan is known as komai-kabe. (literally, wall with small bamboo laces) Wattle & daub also later evolved into the traditional plaster-on-lathe interior wall finishing that was ubiquitous in all western countries until its eventual replacement by drywall panel.
Wattle & daub is essentially an in-fill wall construction technique used to compliment a post & beam structure. A grid of thin wood strips -called wattles- is placed in the spaces between main structural members and then covered in a thick plaster-like mixture -daub- of lyme, clay, and straw (and in earlier periods mud or dung as well) which may then be optionally whitewashed for a bright finish and to protect against rain. Komai-kabe is similar, using a woven bamboo lattice between structural members which is covered with a mixture of clay and plant fiber and smoothed to a very fine finish and sometimes covered with lyme white-wash, paper, or other materials glued on (traditionally) with a seaweed derived glue. Komai-kabe is typically much thinner than wattle & daub and has less insulation value as a result but greater breathability. A modern variation of this technique popular with sustainable bulding advocates in France uses the hemp chard based geopolymer material isochanvre instead of the traditional daub material, affording greater resilience, the ability to mold=in relief decorations, and a warmer feel.
Not actually a complete building method by itself but rather an adjunct to post & beam construction, wattle & daub is a very effective means of enclosing these structures and offers many baubiological benefits but is dependent upon a certain degree of skill for which most contractors have no experience. The very high breathability allows for a healthy indoor environment and lets the walls themselves provide some function as a kind of air filter for volatile organic chemicals. This also makes it well suited to more humid climates, allowing free transfer of humidity rather than trapping it indoors -a key reason for its use in parts of Japan. But it is not well insulated and is less suited to colder climates.
As a non-toxic building method wattle & daub is a very good wall system for use with post & beam structures, though, of course, the ultimate healthiness of the home will depend on the use of chemical-free lumber in that primary structure. It has been specified for use in the non-toxic 'EcoNest' homes designed by new mexico based non-toxic housing specialist Paul Baker Laporte. But very few people have skill with this technique and so finding contractors who can work with it may be quite difficult.
Cast Earth - Sustainable Concrete
Cast earth construction is a fairly recent innovation subject to a number of patents that limit its use and the distribution of knowledge about it. It has long been desired to produce earthen construction with the kind of ease found with slip-formed concrete construction where large structures can be fashioned with little human labor and very little time simply by pouring a plastic material into a large form structure and letting it harden into a strong tough material. But for a long time experiments in making a kind of fluid earth mixture capable of this have had mixed results. Natural earth is itself a mixture that lacks a consistency of composition so devising some other admixture to it which can produce consistent results is rather tricky. Still, in the past few years a handful of inventors have claimed to have accomplished this and now offer home construction services based on it.
Cast earth construction is essentially identical to that of slip-formed reinforced concrete construction, using a system of modular or custom made forms made from steel or wood which are assembled atop a -usually- concrete or cast earth foundation and filled all at once with the fluid earth mixture then removed after the material has sufficuently set. The material can be left as-is or finished in a variety of plaster/stucco/tile/or gravel coatings. its appearance is quite similar to rammed earth and sometimes there is a deliberate use of dyes or variable color tone earth mixes to create the kind of striated sandstone-like appearance so desirable with rammed earth. Roofing and flooring can be the same as with any other earthen construction or as with any slip-formed concrete construction. Design variation is limitless as with concrete construction, albeit with an adaptation to the lower compressive strength of the cast earth material and the need for thicker walls. Labor overhead is quite low but the exclusive nature of the contracting reduces any potential savings this might afford.
As a non-toxic building method, cast earth is potentially very good. But there is a problem with the lack of disclosure by inventors of cast earth mixes as to their actual composition. If they are based on all natural inorganic materials, that's probably fine. One well known mix is based on calcified gypsum which would be quite safe. But they could also be based on the use of epoxies or other polymers and there is no way of knowing ahead of time unless the contractors will divulge their trade secrets. Some are open, some aren't. For this reason it may be inadvisable to use this material even though it could very well be completely non-toxic. Unless the contractors are willing to detail their formulas, there's just no way of knowing and it's too critical to take chances on. Hopefully these companies will realize the folly of their secrets as people start to realize they need full disclosure for health assurance -especially with things as important as a home.
For more info see; The Cast Earth Home Page
The Earthship - Sailing Through Time On A Raft Made Of Tires
The brainchild of architect Michael Reynolds and currently developed and advocated by the Earthship Biotecture group in Taos New Mexico, the Earthship is not just a building method but a sophisticated system of sustainable architecture that has set the contemporary standard for housing sustainability worldwide.
The Earthship is based on a variation of rammed earth construction which employed recycled truck tires to contain the earth rather than a large form. The individual tires are then stacked up like bricks atop a rammed earth footing to form walls and are covered with an in-fill of recycled aluminum cans and then covered in a thick adobe plaster. A roofing system of engineered beams or more natural rustic lumber or peeled logs and anchored to steel rebar posts hammered into the tires is then put on top and finished as a compound roof with playwood or plank sub-roof and a waterproof membrane. Flooring is akin to most other earthen construction with poured adobe, stone, tile, or concrete all usable.
This construction method by itself could be employed for a variety of building styles akin to those where adobe is employed and can accommodate many different roofing systems. But the Earthship system employs a very specific type of building design tailored to its sustinability regime. With the standard design a linear series of 'U' shaped chambers are arrayed in a sloping hillside or against an earth berm. At the front, a common corridor links all the chambers and is flanked by a slanted window-wall angled for best solar exposure. Along this window-wall is located garden channels for hydroponic gardening which are fed by greywater from sinks in the home. A similar system may be used in an outside garden channel for blackwater recycling as well. Cisterns are also built into the wall structure, using a catchment system from the sloped 'lean-to' type roof to collect rainwater. A combination of passive and active solar heating as well as some photovoltaic panels are used to provide heat and energy for the home and to provide heat to accelerate decomposition in the sceptic tank. Altogether, these systems are designed to afford the Earthship almost complete self-sufficiency. Year-round energy from the sun, water from rain or snow, and food from the indoor garden fed by graywater.
As a non-toxic housing system, the Earthship has possibilities but one critical issue. Normally, anything made out of old tires is going to be intolerable to the MCS patient. However, the people at Earthship Biotecture claim that outgassing from these tires is completely stopped and/or filtered by the adobe covering and earth fill which block out any heat or UV light exposure of the tire material. Thus they claim no infiltration of contaminants from these into the home environment. But, frankly, they've never done any scientific analysis of this and so their claim is speculation. It is likely correct but since the only way for the individual to know is to personally test it (and not all existing Earthship interiors will be finished to non-toxic standards) it may present a complication for EIs interested in this type of housing. And, in any case, it is unlikely most EIs will be able to handle these tires themselves during construction which makes the owner-builder option very difficult.
Also, like other earthen construction methods, labor overhead is still very high. Though much simpler than conventional rammed earth construction, the large size and weight of the individual earth filled tires makes them difficult for the lone individual to handle. And there are no contractors readily available for Earthship construction so one is left with only an owner-build option. If an EI cannot build this himself nor hire someone else to do it it makes things rather difficult. Still, the Earthship concept is a powerful and practical one and there is no denying its economy in energy.
For more info see; Earthship Biotecture
Rammed Earth - How To Live In Your Old Stomping Ground
Lesser known that other earthen construction methods and seen primarily in France, China, and more northerly parts of Asia such as Tibet, rammed earth construction nonetheless has an ancient lineage and has recently seen revival among contemporary designers for its unique aesthetics. it is also commonly used in combination with many other earthen building techniques where it serves as an alternative to concrete for foundations and footings.
Rammed earth construction is based on the simple compression of earth inside heavy wood or steel forms by foot stomping and heavy tamping tools as well as by mechanized devices. Building up in layers from a rammed earth or sometimes stacked stone footing, the formwork raised whole for each course of added earth. Cement stabilizer is sometimes added to the earth as with compressed earth block. Roofing systems are generally the same as with adobe construction though in Asia a form of earthen compound roofing is traditional, though its performance is poor without frequent maintenence.
Rammed earth construction has produced some of the largest and most massively walled earthen structures known, simply because the formwork must be pretty wide to accommodate many people standing inside it and stamping the earth down with foot and tools. It is also the single most labor intensive of all earthen construction methods. Thus it has more often been used for large community structures, such as the great monasteries of Tibet. However, in the US it has seen a revival among contemporary architects using it primarily for housing. Their attraction? The unique appearance of the finished wall when a mixture of earths in different color tones is used. The striated appearance is akin to that of colorful sandstone and is so attractive the walls are commonly left unfinished with any other material save -sometimes- a protective transparent wax. The use of massive simple rectilinear shapes also ledns itself to many Modernist designs and the heaviness of the walls affords the ability to support very large roofing beams or trusses to allow the use of large open-plan interiors without sacrificing the virtues of thermal mass associated with earthen materials. However, the very high labor overhead for this method of construction -even with the benefit of mechanized compression tools- has limited its use in the US to homes for the very wealthy.
As a non-toxic building method, rammed earth is quite good and offers all the virtues of other earthen building methods. But its extremely high construction cost makes it largely inaccessible to all but the most well-off of MCS patients -which are a rather tiny minority. However, this technique is well suited to large group effort and could do well for co-housing situations where residents are contributing to communal building efforts.
SuperAdobe - Earthen Housing for Earth and Beyond
California Architect Nader Khalili is a person who looks to the past to see novel solutions for the future. Middle-East born and schooled in architecture in Iran and Turkey as well as the US, Khalili has a strong understanding of the Middle-Eastern traditions of earthen construction and saw in them a novel solution to housing problems both on Earth and on the new frontiers in space. A prime example of this is the technology of SuperAdobe, invented by Khalili and developed by his organization The Cal-Earth Institute.
SuperAdobe is a type of 'earth bag' construction that uses continuous tubing as used for sandbags and agricultural packaging. This tubing is filled with a mostly dry mixture of earth and cement stabilizer and coiled up on a cement-filled coil, rammed earth footing, or concrete slab in the manner of coiled pottery to form structures with arches, vaults, and domes. The coils are filled with earth and laid out in a continuous process. Conventional barbed wire is placed between each course of tubing to help keep it from slipping. Window and door frames are formed by wrapping the coils around wooden frame forms which are later removed for window and door fitting. Once the coiled-up forms of the structure are complete it is covered with a thick adobe plaster covering which protect the material from the tubing from deterioration by UV exposure.
SuperAdobe structures can employ much the same variations in form and design as cob construction -sans the finer sculptural details. Rectilinear forms hosting roofing like adobe housing are possible but require the construction of regular spaced buttress features to reinforce the less stable straight walls. But it is generally limited to the use of vaulted and domed shapes with round or arch-topped windows and doors and single-storey heights which are the easiest to build with the technique. These often feature a slightly below-grade floor, the earth excavated being used to fill the tubing of the structure while the surrounding earth affords a little additional thermal mass. Because roof and wall are continuous with these vaulted and domed shapes, the use of SuperAdobe has tended to be limited to the drier climates in order that rainy weather not wear on the adobe-plastered surfaces. But the use of elastomeric coatings or hydrostatic plasters may afford a wider range of climates.
Khalili and Cal-Earth have also devised solar apse structures where a large slanted oval skylight it fixed at the top of a more cylindrical room form to serve for passive solar heating. More classical style apse structures are also possible.
Developed originally as a means to quick and cheap emergency housing for natural disaster victims and as low-cost housing for the homeless, NASA became interested in the technique as a means to constructing shelters for early Lunar and Mars outposts using the materials at-hand at a landing site. In the space version of this technique, the tubing is replaced with a more sophisticated velcro-strip covered tubing that is filled with regolith to form a shape which is then used as a radiation and meteor shield for an inflatable modular habitat installed within it. Khalili has also proposed the use of another Middle-Eastern inspired earthen construction technique for more permanent space habitats. Using a variation of the Geltaftan technique where and adobe building is fired inside to form a hard ceramic structure, Khalili proposes using solar thermal energy to heat a regolith structure to near melting point fusing the regolith into a hard ceramic material that may be pressurized as-is, without any additional internal lining.
As a non-toxic housing technique, SuperAdobe is promising. It is the single lowest labor/lowest skill earthen construction method that exists, going far to ameliorate one of the primary drawbacks common to all earthen building methods. But since no contractors exist to build with this material one is still limited to an owner-build situation and permits may be difficult to obtain even in areas where adobe construction is common. Also, while the stabilized earth material is itself readily non-toxic, some MCS patients may have difficulty with the nylon, polypropylene, and polyethylene sand bag tubing used to contain it. Similarly, those with EMF sensitivities may not tolerate the coils of barbed wire that are included with this. But since the tubing must be adobe covered anyway to elliminate UV deterioation, outgassing from these plastic materials is going to be low to nil. If necessary, natural fiber fabric tubing may be substituted, though it is harder to find, typically has less strength, and is more prone to deteriorate when exposed to moisture.
For more info see; The Cal-Earth Institute.
Compressed Earth Block - The Contemporary Adobe
Post WWII the countries of the industrialized west began to pursue a variety of international aid programs in the hopes of raising poorer countries to a contemporary standard if living. As well intentioned as this was, it often resulted in great cultural upheaval or was exploited by unscrupulous business interested to create markets -though imposed dependencies- for western industrial goods. A case in point was the well intentioned but ill-conceived attempt by foreign aid workers to impose the use of concrete construction on the Third World as an improvement over the traditional -often eathern materials based- construction methods which these well-meaning outsiders considered primitive and 'sub-standard.' The result was a great loss of knowledge about earthen construction and an imposed dependency on a less sustainable material which in most cases these poorer countries lacked facilities to produce.
Coming to realize this problem, in 1952 more thoughtful aid workers in Columbia invented a simple human-powered mechanical device which came to be known as the Cinva Ram which improved upon the traditional adobe block my forming such blocks from dry or moist earth, with a small amount of added cement stablizer, under great mechanical compression, creating a block of much greater density, uniformity, and compressive strength. This allowed traditional methods of construction to be reintroduced or allowed to carry on while providing greater safety through greater strength of structures and a savings in the consumption of water and the time needed to fabricate blocks. Thus was born the Compressed Earth Block -or CEB- technology which is now found throughout the world.
The basic building methods employed with CEB are generally the same as that of adobe. But the CEB offers many improvements over adobe as a building component and allows for greater flexibility while providing greater performance and a savings in time and labor. The greater physical uniformity of CEBs allows for construction with much less mortar to bind brinks together and in come cases it can be eliminated altogether through precision-formed blocks that interlock rather like Lego bricks. Specialty shape blocks can be created to allow for special structural features or for hybrid construction where reinforced concrete is combined with CEBs to create roof and floor support beams, columns, and the like. This is useful in areas where lumber is scarce or when reliance on lumber is reduced for sustainability reasons. The high density and thus higher compressive strength of CEBs allows for larger structures of many storeys height. It also makes CEBs much more weather and wear resistant so they can often be used without additional protective plaster coatings and can even be left uncovered on interior wall surfaces and still produce an attractive look.
AUM-house with ferro-cement panel roof - Auroville India
The most sophisticated of Cinva Ram product currently available may be the Auram 3000 made by the Aureka company in the Auroville community in India. Using a modular mold system, the Auram produces a great diversity of special function blocks ideally suited to hybrid CEB construction. Auroville's Earth Unit development group has also explored the use of various valt and dome building methods based on CEB and devised a simple but effective prefabricated ferro-cement roofing panel (shown in photo above) which allows for quick roofing construction.
As a non-toxic building method, CEB offers all the virtues of adobe with fewer of its caveats. Labor overhead, time, and maintenance costs are all reduced with CEB and the use of interlcoking bricks reduces the skill levels needed to produce a quality structure. Much taller structures are possible and the hybrid concrete and CEB roofing systems may offer larger spans than single-piece rustic lumber beams can. In general, is one is thinking of building with adobe, CEB is the logical superior alternative. It's only increase in cost is the cost of the block press machine itself, which may be far more than compensated for by the labor saved.
For more info see; The Auroville Earth Unit
Monday, April 25, 2005
Adobe - The Most Common Architecture On Earth
The most well known of the twelve basic earthen construction methods, adobe is the evolutionary descendent of cob construction and has a history of about 10,000 years with equivalents in both the old and new world. Adobe block construction is believed to have been one of human civilization's first mass production industries. It is said that half the population of the planet lives in homes made of earth and most of those are based on adobe construction. In the US adobe is found mostly in the drier climate southwestern states where the adobe building traditions of native Americans merged with those of the Spanish settlers and evolved into the 'mission style' and 'pueblo style' commonly seen today and mimicked with other non-sustainable materials throughout the region. In Europe its use has been confined to the warm dry southern regions where the technology migrated from the Middle East through Moorish/Persian/Turkish influence, being most common in Spain. Elsewhere, it is common throughout most of Asia, Africa, and the Middle East and is in routine use to the present day.
Adobe construction is based on the use of prefabricated clay-rich mud and plant fiber blocks formed with wood or metal forms or sometimes by machine and which are air/sun-dried or sometimes artificially baked. These are stacked into thick walls atop a rammed earth, stacked stone, or concrete foundation and bonded with a moist adobe mortar then finished with an adobe plaster (plain, dyed, or waxed), sometimes a white lyme plaster, or sometimes tile. Adobe block was a great improvement in technology over cob because it allowed for more flexibility in sourcing of materials and schedule of construction, allowed mass production of modular building components, and reduced the amount of water needed at the construction site.
Roofing is traditionally flat and based on the use of rustic wood beams or peeled logs set into the adobe walls. The beams support a ceiling of wood plank or 'latilla'; short thin peeled logs arrayed in a diagonal pattern. Sometimes a thick plaster finish is applied between the beams to create a smooth ceiling look. This use of single-piece beams tends to limit room spans to about a 20' maximum, but as with cob, post & beam structures are often employed to support larger spans and multiple storeys. Roofs are finished with plank or plywood sub-roof topped by tar and a gravel ballast. This is highly failure prone, though, and more modern adobe homes commonly employ built-up roofing akin to commercial buildings or elastomeric membranes and coatings often with a foam insulation underlayment. Metal roofing works well and reduces maintenance costs by virtue of the protection affored by the roof overhang but usually needs a very different kind of ceiling system. Adobe block can also be used to form arches and domes to preclude the use of beams and compound roofing. But this involves highly skilled labor and is limited to very dry environments unless elastomeric coatings or hydrostatic plasters are employed to protect these earthen roofs from wear.
Flooring is commonly poured adobe, stone, or tile but most any other flooring materials can be employed. Since a slab foundation is commonly used in modern 'pueblo style' homes, this is a common underfloor material. Radiant floor heating, its tubing cast in place with a slab, is the norm in higher value contemporary adobe homes as is the use of passive solar heating.
Most adobe homes rely on rectilinear forms as reflective of the block geometry but radial forms are not uncommon. Traditional peublo style homes follow a pattern of conjoined single-room boxes with small windows and doors. Mission style derives from the Ancient Roman villa and is often organized around a central courtyard or series of walled enclosures, an approach also employed in the Chinese tradition. Building structure often merges with exterior walls to create outdoor enclosures and courts. More contemporary designs -particularly those employing passive solar heating- employ more elaborate or, conversely, simpler arrangements with large open-plan spaces fronted by large windows.
Like cob, formed-in features such as shelving, alcoves, and seating/sleeping platforms are commonly used with adobe but the regular shape of the adobe block does not lend itself to as much sculptural freedom as cob. However, cob readily integrates with adobe allowing for more elaborate details if desired, albeit retrofit to the block structure.
As a non-toxic housing approach, adobe is excellent for the same reasons that all earthen building methods are. The materials are natural, breathable, hydroscopic, and comfortable thanks to their high thermal mass properties. The common use of radiant floor heating is a definite plus for the non-toxic home. This is the preferred heating technology for non-toxic housing and integrates well with active solar heating systems. But there are caveats. Modern factory-produced adobe blocks typically feature stabilizer additives in the form of small quantities of portland cement or asphalt. The latter is to be strictly avoided for the non-toxic home but is very difficult to identify in the completed adobe structure. Traditional native American adobe block sometimes uses a natural prickley-pear cactus juice as a stabilizer.
Modern adobe construction also often features a dual-wall system where an air gap is made within the wall to add insulation and host utilities conduits. Some forms of insulation used to fill this gap may not be suited to non-toxic housing and, again, determining the type used can be difficult with the completed building. Also, some of these can be hydrostatic which ruins the hydroscopic qualities of the earthen material and can lead to humidity build-up and mold growth. The same problem results from combining inappropriate wall finishing materials -such as polymer based stuccos- which can trap moisture.
Like almost all earthen construction methods, labor overhead for adobe block construction is very high and unless one can build a home oneself realizing any savings over other construction methods is unlikely. Maintenance is also high, though not as great as cob due to the stabilizers common in modern adobe.
For more info see; The Adobe Alliance
Cob - The Original Earthen Building Method
With a history going back in excess of 10,000 years and examples common in both the new and old world, cob construction is probably the oldest of the twelve basic methods of earthen construction and possibly the oldest method of construction in human civilization. However, most of the methodology employed in its use today originates in the British traditions of cob construction some hundreds to thousands of years old. Cob housing has become very popular among sustainable architecture enthusiasts as a result of the work of the Cob Cottage Company in Oregon which reintroduced the technology to the US and established its contemporary style. Their web site and books offer the definitive source of information on the technology.
Cob homes are often attributed with a serene ambiance or neo-primitive charm as a consequence of their combination of natural materials and organic/rustic design. Very popular with builders of an artistic and/or counter-cultural bent, designs often diverge into wild free-form variations featuring elaborate hand-sculptured details.
Cob construction is a primitive form of adobe construction based on the use of moist hand-formed loafs of clay-rich mud and straw which are mixed on-site, stacked up in courses to form walls, and often sculpted into the shapes of built-in fixtures such as shelves, benches, and bedding platforms. Wall finishes are usually natural plaster or adobe -plain or waxed- but materials like isochanvre can also be used. Flooring may be poured adobe, stone, tile, concrete, or most anything else that can be applied on top of those. Rustic wood plank flooring is the norm for upper floors.
Cob buildings are typically built on a stacked stone or concrete foundation fairly high above grade level -compared to typical foundations- and are topped-off with sloped roofing with a wide overhang to protect the cob walls from rain. Roofing type varies but contemporary designs favor wood shingle and slate roofing -often with decorative pattern treatments- on natural peeled log beams while the British tradition favors slate or thatch roofing on post & beam trusses. Very large structures commonly supplement the cob primary structure with a post & beam structure to support large spans and numerous storeys.
In the British tradition cob structures follow rectilinear building forms and can sometimes be several storeys high. In the contemporary style, single or two storey cottages with curving forms, small rooms, and elaborate sculptured details predominate. Curving forms are stronger than rectilinear forms, allowing novice owner-builders to produce sufficiently strong structures despite their inexperience with the material and building in general. In drier climates cob can be used in manners identical to adobe and in some cases has been used to make domed roof structures, though usually with another material -such as elastomerics or special hydrostatic plasters- added as a protection and some kind of reinforcement lattice to help support the structure under construction.
Though based on earthen material, cob buildings have proven practical in a very diverse range of climates including the notoriously damp climates of the UK and Oregon. This is due to the use of those wide roof overhangs and high foundations, as opposed to the flat roofs common to the pueblo style of adobe construction which cannot protect the structure sufficiently in persistent damp weather.
As a building method for non-toxic housing, cob is very effective as long as the earth sourced for construction is free from contamination -which is not always a given in the US. Offering the typical benefits of all earthen construction, cob buildings enjoy low energy costs due to high thermal mass and the materials normally used are naturally non-toxic, hydroscopic (meaning it absorbs and releases moisture in response to ambient humidity averaging out extremes), and breathable. (allowing a small slow amount of air flow through walls and their finishes) From a material standpoint cob is 'dirt cheap' but in practice such homes are only inexpensive when owner-builders have the physical ability and free time to perform most construction themselves. Labor overhead for cob construction is very high due to its heavy reliance on hand work and while even the most inexperienced can often produce serviceable structures, some skill and talent is necessary to realize attractive results. If one cannot build oneself, a cob home -like most earthen structures- can cost much more than a conventional stick-built homes. Cob also requires a routine schedule of maintenance in restoring the exterior surface finish due to weathering and this maintenance increases with the degree of dampness and temperature variation in the regional climate.
Cob homes very often rely on low-tech utilities, in particular wood stoves and fireplaces for heating. These are inadvisable for non-toxic housing which should normally avoid all forms of combustion energy appliances.
For more info see; The Cob Cottage Company