Here’s another good way to build an inexpensive roof if you have access to wood poles from a forest. Like many of the ideas here on this blog, this design is for areas with few or no building codes. One way to get the wood is with a firewood permit from the forestry department/forest service. The wood that would normally be cut into firewood can be used for more valuable homebuilding projects such as posts, beams and timber roofs such as this one. Besides saving money, a key benefit of this design is ample space for roof insulation. The dimensions can be adjusted to hold as much insulation as you want.
The basic building process is as follows:
– Obtain the straightest, most uniform poles you can find and dry them gradually under cover. Paint or varnish the ends of the poles immediately after cutting to reduce cracking. Cut the poles an extra foot or two longer than needed so you can later trim off the cracked ends.
– Make a simple jig to ensure all trusses are the same size and shape.
– Cut the poles to length. Select the straightest, best poles for the long pieces (top and bottom chords). There’s greater load on the top chord, so use slightly larger diameter poles on top. Crown the poles before cutting. Measure twice, cut once.
– Make curved cuts in each end of the short vertical poles. This is the most difficult step. Using a cardboard or plywood pattern, make numerous kerf cuts about 3/8”-1/2” (10-12mm) apart with a chainsaw. Break off the biggest pieces with a hammer. Carefully rough out the cut with the chainsaw tip, and then clean out the cut with a timber frame gouge or similar woodworking gouge. The ‘sweep’ or curvature of the gouge should approximate the cut you’re making.
– Recoat the ends of the long poles for greater durability. This time you might want to use a good quality exterior wood stain. Slosh it on and let it really soak in.
– Prefit and screw the pieces together on the ground or on sawhorses. Mark the pieces, disassemble them and screw back together on the wall. Brace in position until walls between trusses are framed in. Sheath these walls with plywood or wood siding.
– The hurricane ties are larger than standard, so you might have to order them. The straps are approximately 10”-12” long if you’re using 12” poles. You can use hardware by companies such as Simpson Strong-Tie. Other brands will work just as well.
– Install purlins and roofing.
– The ends can be left exposed or boxed in for a more finished look.
Double Pole Roofs