Straw Bale Building Roof Trusses — DIY v

Straw Bale Building Roof Trusses - DIY v

Straw Bale Building: Roof Trusses — DIY vs. Manufactured

6/27/2011 5:07:45 PM

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.

On the other hand, when it came to be time to build our main house, we shopped around within 75 miles of our site and got bids from three different truss manufacturers. Our chosen vendor was able to custom-make and deliver trusses, vent plates, and end trusses with vents for $63 USD in 2009. Our hand-built road is too narrow and curves too tightly for a flatbed trailer, so our trusses were dropped off at our neighbor’s place. When we were ready, we loaded them in Dan and Anneke’s horse trailer and carted them over to our site.

With a 100’ tape, we measured and marked the truss locations on the bond beams before lifting them into position. Then, again with the able assistance of our neighbors, we lifted the trusses to the top of the wall. Two lifters on the ground pushed the trusses up to the two catchers on the wall. It took less than an hour to move them all into place.

Straw Bale Building Roof Trusses - DIY v

We began with one of the end trusses, cut to accommodate the vents, and a second truss. Cross braces were installed from the end two trusses to the bond beams to make a secure, rigid box.

Then it was position each truss in its turn, check for plumb, and fasten it with hurricane straps. As the trusses were secured at the bond beam, a cross brace toward the roof peak was nailed into place and vent plates at the roof edge were installed.

It was such a great feeling to look down the peak of the trusses and see the perfect alignment and know that the sheathing and the steel roofing would go on with ease. This was the payoff for the extra time we took to square the foundation, the walls, and the bond beams as we built. The trusses were all mounted and secured in one mornings work.

Our DIY work in almost every other aspect of our buildings was more than satisfactory. But the ease of installation, the comparatively low cost, and the quality of truss construction with our purchased trusses make them a no-brainer for us. Happy Building!

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