Straw Bale Building: Roof Trusses – DIY vs. Manufactured

Reader Contribution by Dave Larson
Published on June 27, 2011
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When Barbara and I undertook the building of our homestead in the desert, we committed to doing things ourselves as much as was reasonable, even some things that were perhaps unreasonable. One project that began as a DIY and morphed into using a manufactured product is roof trusses.

Our adobe Bear Cave, the first building to go up, was also my first attempt at DIY roof trusses. I read articles and books and looked at pictures and drew sketches by the dozen before creating a plan for a roof that I liked. We decided on a simple shed roof truss with the porch rafters attached to a plate at the front of the truss to create a gabled roof appearance. 

 As the only level place on the building site was the well-tamped sub-floor, I laid out a couple sheets of plywood inside the building, fastened them with a scab and laid out a truss jig. Because I was hauling all our dimension lumber on the roof rack of my old Blazer, I was pretty much confined to ten-foot lengths. As the bottom cord of the truss needed to be 16 feet long, I had to make a joint in two 8 foot 2 x 4s. With an 18 ft top chord to provide an overhang out the back of the building, I used a 10′ and an 8′ 2×4 for each truss.

The result of all the labor was a system of trusses that was satisfactory, but just barely. Our lumber was off-the-shelf dimension lumber from a big box building supply store and tended to twist and warp. Because we were using purlins rather than sheathing, nailing was not the disaster it might have been. To compensate for screwed and nailed steel joining plates, we put extra scabs on the trusses to reinforce them. Once they were mounted on the bond beam and secured with bracing, they work just fine. But compared to manufactured trusses, they just don’t make it for me. Way too much work for very little savings.

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