Frequently Asked Questions
- Aren’t these houses more susceptible to fire?
- How much would a person spend on a straw bale house?
- Will a straw bale house be prone to rot and mould?
- Is there a problem getting straw bale homes approved by building Inspectors?
- How long will a straw home last?
- Straw is not very strong stuff. Won’t these houses be at risk of falling over?
- Do straw bale houses have problems with insects or rodents?
- Do straw homes use more or less wood?
Surprisingly, according to several studies, straw bale homes are actually more fire resistant than conventional wood frame houses.
“Bale walls withstood temperatures up to 1850°F for up to two hours.”
Source: Fire safety tests, National Research Counsel of Canada.
“The bale panel was tested for over two hours and withstood temperatures that reached 1942°F. The temperature rise on the unheated side was less than 10°F.”
Source: ASTM E-119 Fire Test. SHB Agra, New Mexico, USA, 1993
A contractor built SB house built to R45 standards will often cost the same as a similarly sized and styled conventional 2×6 contractor built “stick frame” home. The “average” price per square foot for a new conventionally built home in Ontario is $100 per square foot.
Providing that care is taken to ensure that the straw does not get wet prior to plastering, the straw within the walls will not degrade.
“Straw bale walls do not exhibit any unique propensity for moisture retention. It’s clear that straw walls can function without incorporating a vapour barrier in northern climates.”
Source: Straw bale moisture monitoring report submitted to the Canada Mortgage and Housing Corporation. (CMHC) by Rob Jolly, 2000.
By meeting with the inspectors and providing documentation showing that building with straw is safe, sound and makes good sense; many clients have received positive responses from building inspectors. Having your plans certified and stamped by a Professional Engineer or Architect helps removes the risks and also the apprehension of the municipal Inspector. Green Planet Homes can assist you during this stage of your project by providing you with a list of recommended documents to present to the municipality. We can also arrange to meet with you and your Inspector to discuss any questions or concerns.
There are straw bale houses in Canada and US which have stood for nearly 100 years.
Straw bale walls have been tested to be 10 times stronger in load bearing strength and 4 times stronger in lateral strength than conventional 2×6 stud frame walls.
Straw does not have any insects, which prefer to feed on or live in it. While mice and rodents may like to make homes between bales of hay or straw in the barn, they are not likely to burrow into the bales themselves due to their density. Once the plaster is on the wall the rodent would have to chew through an inch and a half of cement lime plaster to gain access to the interior of the wall. As a result, straw bale houses are no more prone to rodent problems than conventional homes.
“A stick frame building of equivalent interior size and style would have required 47.5% more lumber than the bale building constructed.”
Source: (CMHC) Technical Series “Wood Usage in Straw bale Construction”