Straw Bale Roofing

September 29, 2010

albertson roof 1

Last Friday, miracle of miracles, I actually got to be out on the job site rather than just perched in front of my laptop as a factor of my work at Whole Trees.  Roshni and I got tagged to come for and “all hands on deck” day at the Albertson house.  We went for a day and a half to help “stuff” the straw bale roof.  I’ll borrow below from my own text about this process originally written for the whole trees “Log Blog” here.

Straw bale roofs are a really fun process, Whole Trees, style.  After the rafters are placed we stretch an interior finish of canvas between them and then create a good strong vapor barrier and fireproofing layer with a techfoil and airkrete layer.  Then a tightly stacked layer of strawbales are laid out to cover the whole roof surface.  But the work is far from done.  The bales are tightly cinched down to the rafters below by wires threaded up through the bales and secured to wooden purlins which run in the opposite direction.  Above you can see one of the crew members, Prairie, working to tension a purlin row as he works his way up the roof.

albertson roof 4Once purlined the straw bales are very secure.  But the roof isn’t perfectly insulated yet.  Because of the curving form of the roof there are little spaces between some of the bales.  To stop those gaps from being thermal breaks we go back and pack each one with more loose straw, tamping down until the straw bale is a relatively homogeneous insulation layer.

Roshni and I were deputized to undertake this “stuffing” process.  Here I am demonstrating how I can stick my hand right through between the bales and all the way down to the roof rafters below.  Filling all those gaps was quite lot of effort but it was SO fun to do.  Sitting on the bales looking out at beautiful countryside and feeling the wind blow while talking to the other people on the roof was just a delightful way to spend the afternoon.  Hard to believe it was “work.”

albertson roof 3

albertson roof 2The packing process can be meditative, as you contemplate the warm winters you are providing, or therapeutic as you dissipate frustration with each firm thump of the tamping stick.  Roshni and I worked methodically back and forth across the rows of bales while Praire traversed the roof tightening and securing purlins and Roald installed the chimney assembly.

We didn’t exactly whistle while we worked but there was plenty of friendly discussion, banter and even a little singing.

Here’s the whole roof, soaking up the sun and just waiting to be covered over in the final metal decking layer!  Its currently being protected from wind and rain by heavy plastic tarping … which is actually re-purposed billboard signs.  We practice what we preach about material re-use and recycling here at Whole Trees!

albertson roof 5

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