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Anybody dense pack a truss bay as part of a hybrid roof?

Micah_Witri | Posted in Expert Exchange Q&A on

Good Morning,

I’m in zone 5 (southern RI) and I would like to do a hybrid roof with rockwool comfortboard on the exterior of the sheathing and dense pack cellulose on the interior. I would also like to have attic trusses over 2/3 of the house for storage, and scissor trusses over the other third to create a vaulted ceiling. Ideally I can keep the same roof detail across the whole building for both the unvented attic space an the vaulted ceiling.

I was thinking I could fill in the truss structure with 2x or plywood and insulweb each side. Then add nailing (probably a ripped down 2x) to the side of each bay and the gables and insulweb that as well. Then the insulation could be packed against the sheathing and that webbing. I’m planning around 7.5″ of dense pack cellulose, then 5″ comfortboard (R29ish/R20ish). Additionally the roof assembly would go: sheathing, vaper open membrane, rockwool, strapping/vent space, sheathing, membrane, asphalt shingles and vent the space to the facia with a sealed and insulated soffit space.

 I worked as a frame to finish carpenter for 8 ish years and I  like how fast trusses go up and easily create an open floor plan so the interior can be arranged however or easily be changed later. I also like that trusses are pretty economical and allow you to cover a house back up quickly (this is a renovation)


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