How long do straw insulated houses actually last before you have to replace the straw? What is the threat of mold, fungus, insects and other pests?
There are two options for insulating houses with straw. The straw is the primary structural material in some straw-bale homes — it actually holds up the roof. More commonly, post-and-beam or timber-frame construction forms the skeleton of the building, but straw is used to fill and insulate the space between wooden posts.
With either system, the straw must stay dry and is enclosed with some kind of plaster to protect it from insects and moisture, which would allow mold or fungus to develop. Other techniques to keep water from wicking from a concrete foundation into the straw are also necessary. If the straw gets wet and stays wet, it turns to compost. But if you keep the straw dry, it won’t need to be replaced for the life of the building, which should last much longer than a human lifetime if built correctly.
You may, however, need to repair the plaster. The frequency of plaster repairs depends on your climate and the type of plaster you choose. For more detailed advice on building with straw, read Expert Advice on Straw Bale Building and Our Dream Green Home in our online archive. If you’re looking for specifics on choosing the right plaster, check out Perfect Plaster and Get Muddy! Make Earth Art.
— Troy Griepentrog, associate editor