Straw bale construction is a really simple concept, if you ask Fleming College sustainable building design and construction program instructor David Belsey.
“It’s just a different form of insulation. That’s all it is,” he told those gathered at the outdoor education centre being constructed at Thomas A. Stewart Secondary School as the project was showcased to representatives the college, public school board and the media.
It was a chance for them to learn about the natural construction method from Belsey, who dispelled the three myths he routinely encounters on the topic.
The biggest that straw bale buildings are a fire hazard. He agreed there is a risk during the installation process, but once the hay is coated in plaster, it cannot catch fire.
The second myth is that mice, snakes and insects often call hay bales home. They do, but because the hay itself isn’t actually a food source, any wildlife almost always skedaddles during the construction process, Belsey explained.
The third is that mould is a problem. The program examines and employs best practices, like using bales with the proper moisture content, so that’s not an issue, he said.
The idea is to make the building – which is expected to last seven generations – as carbon-neutral as possible, Belsey told those gathered in the wood-frame building. It’s ultra energy-efficient design includes R14-rated windows, for example.
Walls building with plaster-coated hay bales can have as much as five times the R-rating of traditional drywall, Belsey said. Loosely-packed hay can have a value of as low as R25 while more tightly-packed bales can provide ratings up as much as R50 or R60.
The instructor pointed out how farmers will often line the inside of their barns with stacks of hay bales for insulation during extreme temperatures.
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