If all goes well I’m going to put up a shop building this spring or summer. Simple rectangle about 24 x 36, slab floor, 9′ ceiling, and then a ‘loft’ above under the rafters. I’ll stick-frame the roof, a simple single gable at about 8/12.
Many years ago, 1000 mile south, I did a similar building. The rafters were 4×10 DF#1 resawn at 4′ O.C. The roof decking was 2×6 t&g knotty pine. From below this looks great… sorta timber-framey, a nice warm look. Over the top of that decking we added 2″ rigid foam and a layer of ply, then shingles.
That was enough insulation for that building, but I don’t know if it will be here. We get very little snow (maybe 1x per year) but we get a lot of winter days in the 30s and I don’t want an under-insulated building. Of course I could go with typical 2×10 or 2×12 rafters and plywood roof sheathing, and just insulate R-30 between the rafters, but then I’d have to rock the underside of the rafters and that’s a whole different look. Rather have those nice 4x rafters and the t&g decking to look at.
Anyone got a similar building, and what was your roof detail?
Replies
I like your rigid insulation idea. It's covering the roof 100%, vs. insulating between wood members which are poor insulators. The heat/ cold conducts right through wood members. You'd never want to work in a steel building that was insulated between the beams.
I see a Mooney roof emerging . . .
"If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man." - Mark Twain
SIPs. I believe you can get them up to 12" thick.