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Natural Building—Straw Bale |
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Straw bale - Frequently Asked Questions
How do you use straw bales in buildings ? The bales can serve as in-filled insulation between post and beam construction or can be load bearing (sometimes called 'Nebraska style'), where the roof rests on top of a special collar that ties the top of the bales together. The bales are alternately stacked on top of a foundation to keep them dry and basically follow the shape of this foundation including the ability to bend to some degree.
What advantage is there to straw bale walls ? Straw bale wall insulation is it's superior quality. The typically R-40 walls also have a breathing characteristic that artificial insulators do not in addition to their out gassing of toxins. Bales represent a quicker regeneration cycle than wood and can be grown on a site with the grains going for food and the chaff becoming the wall insulation.
Isn't it a short lived wall ? Baled straw, as we know it, only goes as far back as the mechanical baler. Today there are sound examples of early straw bale walled homes built in the early part of the 20th century. Much like wood in this way, straw bales must be protected from the elements (water in particular) or rot will consume it's structural integrity. Given a reasonable amount of protection such as a roof with overhangs, an impermeable foundation and a maintained plaster coating, straw bale construction will last for centuries. Today's baling machines also provide superior strength bales to many that were built earlier in the 20th century.
Won't it catch fire ? Tightly baled straw has been proven to burn very poorly. A lack of air within the bale causes it smolder rather than ignite. Typically house fires in modern structures gain strength through a 'chimney effect' caused by the air gap between wood studs. This, in addition to dried woods likeliness to ignite quickly makes non straw bale wood frame housing more fire susceptible. Wall plasters (below) further decrease the likelihood of a fire. Using standard fire testing, plastered straw bale walls have received very high ratings.
What do I use to cover the walls ? With the recent revival of straw bale construction concrete stucco has been the major choice for plaster. More recently many experiments (including EarthVoice's) have been done with earthen based plaster. Typically several successive coats an outer coat that includes lime creates a long lasting, environmentally friendly and inexpensive plaster.
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Green Living Network |