A catalog of non-toxic building systems.
Saturday, June 4, 2005Wood 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.