The three little pigs knew a thing or two about building houses; with a big bad wolf prowling around they had to. Brick – good. Wood – not so good. Straw – forget it. But if a wolf is not threatening you there are many reasons why you might want to consider building a house made of straw.
Straw has been used as a building material for centuries but it’s long been associated with developing nations. Wattle and daub homes or adobe huts conjure up images of primitive living. Early settlers in the United States built strawbale houses, some which are still around today. Over the last decade or so people have been looking at straw as a construction material with fresh eyes.
Straw is cheap and plentiful. We use the cereal crop for food and the straw is a by-product, which is often just chopped up and put back in the soil or used as animal bedding. So there’s plenty of it and it doesn’t cost much money. It’s also a carbon store, as carbon is locked into the material.
Straw is a great insulator, both for heat and sound. Straw bale houses are warm in winter, cool in summer, and the thick walls deaden sound transmission very effectively.
Sounds great, but there must be drawbacks. What if it rains, won’t the house get soggy? And surely it’s a fire risk? Rain can of course damage any building and you do have to take extra precautions with straw, paying particular attention to making the design of the building rain-resistant; for example the external rendering should be lime render which allows the building to breathe; and build large roof overhangs (at least 500mm) so water doesn’t run down external walls. Fire isn’t any more of a risk than with any other natural material. It’s extremely difficult to set light to a straw bale. They’re packed together very tightly, so there’s very little oxygen in the blocks.
It’s easy to cut and shape straw. Bales can be cut with a chainsaw, so you can quite easily create shapes that would be far more technically challenging than with brick. Curving, flowing walls are a common sight in straw houses.
Before you rush down to your local farmer to order 500 straw bales, don’t imagine that straw bale homes are cheaper than those built from conventional materials. Straw is cheaper than brick, but all other costs – labor, interior fittings etc. will be the same.
So perhaps it’s time to reconsider straw as a mainstream building material for areas where the climate needs extra insulation. And, that story about it blowing down from a huff and a puff? Sounds like a fairy tale to me…