The New Strawbale Home: The Healthy Home

Creating a healthy home involves many considerations, including nontoxic building materials, healthful indoor air quality, and avoiding molds, allergens and pests. Most of us can tolerate modest levels of pollutants in our environments, but some sensitive individuals cannot. And perhaps tolerance is not appropriate, when small exposures can build up to a damaging level over time.

Indoor air-quality problems have a huge impact on our economy and the well-being of millions of people. Modern building materials such as plywood, wood-chip boards and fiberglass insulation are held together by formaldehyde and other toxic glues. Formaldehyde is also found in carpet, which off-gasses for weeks after installation. That wet-paint headache comes from “volatile organic compounds” (VOCs) in the paint formula. PVC and vinyl are fairly inert while in your house, unless a fire starts. When they burn, they release poisonous chlorine gas. The list goes on and on. You can make healthier choices by reading the labels on the materials before you buy.

Easy things you can do to improve indoor air quality are:

• Avoid carpeting or choose natural fibers.
• Instead of insulating with fiberglass, try cotton batts (made from recycled blue jeans material) or blown cellulose.
• Use “PEX” tubing, which comes in rolls like garden hose, to replace PVC plumbing parts. This polyethylene tubing costs more but installing can be much quicker.
• If you are concerned about electromagnetic frequencies (EMFs), run electric wires through conduit, and locate your desk, bed and kitchen away from power sources.

Aliz, or clay slip, is painted on the wall and polished.

“Sick building syndrome” is a product not only of modern materials, but also of naturally occurring “biological air containments.” The vast majority of molds, fungi and bacteria are benign, but a few, such as the black mold Stachybotrys, can make you sick with flu like symptoms. The key to prevention is to understand how these microbes thrive. Mold and mildew prefer dark places and need moisture, warmth and food. Wet cellulose building materials (carpeting, particle board, plaster board, etc.) can provide a good growing medium. So can the lint that collects in dark, moist heating and ventilation ducts.

• Mold hates sunshine and oxygen, which are naturally antiseptic. So consider a design that allows fresh air and sunshine to help sanitize your indoor environment. And be aware in your design where moisture may build up inside—such as the bathroom. Even a simple exhaust fan can be enough to eliminate mold habitat. Don't wait to repair plumbing leaks or moisture problems, as minor drips can cause major hidden headaches. Left unchecked, mold damages what it feeds on, including your wood-frame structure.
• Avoid forced-air heating and cooling systems, which employ duct work that provides habitat for fungal growth. Though some systems offer excellent filtration for tiny particles, without maintenance they can actually blow moldy dust particles directly into your living/ breathing space. Radiant floor heat is silent, superior in comfort, can cost less and requires no duct work.
• The plaster you choose can also play a part in creating a healthy environment. Lime is well known to have antiseptic and antifungal properties, so some homeowners choose it as a finish for bathroom and kitchen walls. (Use caution, it is caustic to work with.) Clay plasters are praised for absorbing odors and softening sound, and evidence suggests clay is also an air purifier. Earthen plasters can often be made from on-site soil and applied safely with bare hands and without protective eyewear. (You can give yourself a facial at the same time.) Clay plasters will also act to moderate humidity inside homes by absorbing moisture from the air and storing it—providing the perfect humidity range for human health, according to baubiologists.

Chemical Allergies: There's a very low likelihood that chemicals used in growing straw will hang on to have ill effects for individuals who have chemical sensitivities. Straw tested for pesticides showed extremely small amounts of residue, for most grains, chemicals are used early in the growth cycle and then discontinued.

• If you have allergies, a dust mask should protect you during the wall raising, and once the straw bales are sealed with plaster, dust, chemicals, and allergens are sealed in, too. Chemically sensitive individuals are happily living in straw bale homes, but for peace of mind, spend some time in other strawbale structures before you build your own.

Insects: Compared with wood, few termites make a meal of straw—in fact, there's not one report of termites seen in bale walls. And clean, dry bales typically contain no mold colonies or insects. But like mold, the occasional report of insects can always be traced to wet bales. If insects have laid eggs in bales, moisture will trigger hatch-out—typically of tiny beetles or mites. These have proven more a nuisance than a serious problem, and fortunately, when the bales dry out, the insects disappear.

• Straw bales should be yellow—avoid using dark, discolored bales, or parts of bales. This means the bale was wet at one time, and the discolored areas will contain dormant fungal spores. Compost those parts in your garden instead of putting them in your wall.