Cellulose Hot roof application?
I am trying to build a super or well insulated workshop with upstairs room. The main story are walls made from ICF, the upper are trusses with “room in attic” setup. It has a steel roof on purlins. with the top chord of the trusses being 2by8 and 2by4 purlins (stood up) i think i have created a decent amount of space to insulate. i was hoping that this would mitigate issues with the sloped part of the wall ( this area in my house, a cape cod, seems to be problematic for heat loss)
my original plan was to have a sprayfoam hotroof approach, but the more i learn about sprayfoam, the less i like it… i like the idea of using cellulose. i then thought about doing a flash and bat system, using cellulose over 1-2 inch of sprayfoam (to seal things up) . i wouldn’t be opposed to cellulose only method of insulation (dense pack). but the problem seems to me is: can cellulose be used for a hot-roof approach?. i have never heard of this being done, but i’m sure there are countless vaulted ceilings out there that are full of cellulose (although that doesn’t make it right). also, if this is an approved method, will the pressure of densepack make my metal roofing bulge? its 28 gauge screwed on 24″ centers
i thought i had it all figured out, but it seems to me the more i research (as i build) the more decisions i have to make.
building is 25 by 32, i live in wisconsin, simple gable roof, 12 foot ceilings on first floor, and 8′ on second (attic) floor room.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part