How Straw Bale Houses Work

Straw Bale Building Challenges

As we've mentioned a few times in this article, moisture is the biggest physical problem of building with straw bales. Moisture in the bales causes mold, which causes the straw to rot. You have to take precautions from the moment you buy the bales. A rainy day of construction could ruin exposed bales, so when the bales arrive on site, store them off the ground and under tarps.

During design and construction, take special care to keep water out of the home. Just as the toe-ups on the foundation provide protection from moisture below, roof designs that incorporate overhangs will provide protection from above. Windowsills and joints must be carefully sealed. These methods will keep out the liquid dangers posed by rain or snow, while using the natural, breathable plasters mentioned in the previous section will keep moisture from the air moving through the home. Cracks in these plasters are the primary maintenance issue for straw bale homes so that moisture doesn't accumulate in the walls.

Straw bale home before plaster
Photo courtesy
Straw bale home before plaster

Straw bale home after plaster
Photo courtesy
The final product

Because straw bale building is fairly new in the construction world, one of the main challenges of building a home in this way relates to how the outside world sees it. Someone interested in straw bale building will likely have to jump through more hoops than if building a conventional home. Building codes might not account for straw bale methods. Conservative banks, lenders and insurance agents may not want to take a chance on financing such an experimental method.

If you want to build a straw bale house, particularly in an area in which they're not common, you might have to work more closely with building officials to get plans that will meet codes and pass inspection. To gain financing and insurance, be ready with data to help explain straw bale building to someone who may not have heard of the method before. You may have to hire consultants to look over your plans and methodology and to vouch for you with the institutions.

How do I find a straw bale contractor?
With straw bale construction still fairly outside mainstream construction methods, it might be difficult to find a contractor knowledgeable about it. "The Last Straw," the quarterly journal about straw bale building maintains a list of resources. You can also check out this database of green builders: It might be easier to look for contractors to provide individual services, such as plastering or roofing. Just as you need to be well versed in straw bale building to deal with banks and insurance companies, you'll need to know how to work effectively with the contractor

­­As for reselling a straw bale home, little data exist, maybe because straw bale owners don't leave them. Some evidence suggests that straw bale homes might receive a lower resale value estimate than conventionally built homes [source: Magwood, Mack, Therrien]. However, this is another place where an educated owner/builder is important; explaining to a potential buyer the value of a well-insulated home may help someone decide to pay more than the appraised value. 

But what if you've already built a house? We'll learn how to build straw bale additions and retrofit existing structures on the next page.