nikwax wrote:I can get rigid insulation at Home Depot in 3/4", but I'm not finding flexible insulation for the curved parts. Can anyone recommend a type/source of flexible insulation?
You're gonna have to cut your big sheets of rigid to fit and lay between the spars--it doesn't have to actually bend.
Even if your spars are 24" on center, it'll fit in there without any real bending. And if your spars are closer together, that's even LESS of a problem.
Know what I mean?
If your tear is 4' wide and your spars are 24" on center for example, you're gonna cut each piece of insulation 24" high (minus a bit) and 48" wide (minus a bit).
Do you plan 3/4" total thickness for roof insulation, or 2 layers for a total of 1 1/2"? If the latter, you can kerf--slice into it--to make it bend and fit the 2 layers in there between the spars.
Stick with rigid foam and stay away from roll insulation, which can create problems for you if you develop any leaks.