Home Sweet Dirt and Straw Home
- Aug 27, 2007
We all know what people in glass houses shouldn’t throw — stones. (Actually, it’s probably not a good idea to throw anything if you live in an all-glass house.)
But what should people who live in straw houses abstain from doing?
Absolutely nothing, according to a new green building trend that is encouraging use of materials like straw, compressed dirt/rammed earth, an adobe straw mixture and aerated concrete blocks. (Lists of such materials can be found here, along with straw construction information.) Builders had in the past shied away from such materials because of fears they were highly flammable, not durable or just outdated.
Straw was a somewhat common building material in the late 1800s and early 1900s when Midwestern and other pioneers couldn’t find timber, the Austin American-Statesman reports.
But the industry is now learning that some ancient building sources and techniques have very modern applications, for the following reasons:
- They’re reasonable. Materials such as rammed earth are low-cost material alternatives with low embodied energy, according to Sustainable Sources’ Sourcebook for Green and Sustainable Building.
- They’re energy savers. Architect Ben Obregon built his Austin,
Texas home using rectangular straw bales for walls, which were covered
with stucco outside the home and adobe plaster inside. He’s reduced his
monthly utility bill for the 2,135-foot home to $55, the Austin Statesman reported.
- They’re actually quite safe. Scientific studies have proved that straw bale construction is actually very resistant to fire because of its tight packing, according to the Daily Green.
- They’re in supply. One five-acre pit could supply earth walls
for 5,000 homes, according to the Terra Firma Rammed Earth Builders company. However, suppliers and builders must be careful not to overharvest an area’s rammed earth capabilities, or they’ll be causing the same problem they’re trying to solve.
So why aren’t we all living in dirt- and straw-constructed houses? Permits can be hard to get because building codes rarely mention alternative building materials.
"Unfortunately, by not addressing specific
earthen materials and construction techniques, codes restrict the use
of these materials and types of construction, even those that may have
a long history of success," Fred Webster, Ph.D., P.E., of Fred Webster
Associates, known for its adobe building, wrote in an article on green
Insurance, as a result, can be hard to obtain for a rammed earth or adobe homeowner.
"Because of their standardizing Influence,
building codes are viewed by lending institutions as a rational and consistent
basis for judging the risk in lending mortgage or construction dollars," Webster says.
And there are some viable insurance concerns. Water is a huge issue. A World Housing Encyclopedia report cited potential issues like roof leaks, which can cause major expenses if the soil crumbles.
Extra care must also be taken to waterproof the exterior walls, create roof overhangs and seal the doors and windows, the American-Statesman said.
But all homes pose risks, which is why insurance exists — and the risk factor doesn’t mean homes made with earthen materials are unrealistic housing options.
Are you hoping to reduce sound? Energy costs? Cut material costs?
Examine the different building materials and determine which will work
best for your construction.
Also take note of where you live. If there are heavy rains, you may need to build on higher ground and/or add design elements that will keep the house as dry as possible.
And always, if you’re considering building using rammed earth, straw or another sustainable material outside of the norm, talk to your local building department about the current codes and how you might obtain a permit.
This process might require educating them a bit, and may take some time, but always remember, communities are not averse to making building code changes. After all, if it’s good enough for the Great Wall of China — parts of it are made of rammed earth — shouldn’t it be good enough for your community?