9×18 enclosed porch area with a shed roof.
What I’d like to do is raise the 7ft exterior wall to 10ft by resting two 8×8 horizontal 18ft barn beams on 10ft 8×8 verticals at the corners,
two other 8×8 vertical 10s sitting mid span exposed to the interior. Same 9ft horizontals running across joining the verticals.
12ft 2x roof joists running from the house at a walkable pitch creating a deep overhang. 3/4inch t&g OSB sheathing with shingles.
Can I place 2 inch DOW blueboard on top of the roof joists and screw the OSB with 4inch screws?
If going with 2x8s will 24inch on center suffice? If 16″ on center will 2x6s work ok?
Replies
Can I place 2 inch DOW blueboard on top of the roof joists and screw the OSB with 4inch screws?
My guess is you'll have trouble keeping the roof sheathing flat that way, plus over time the foam board will compress where it sits on those joists. The stuff ain't structural. Think you'd be better off building a 'sandwich' with sheathing below and above the foam. That'd eliminate any point loads on the foam.
If going with 2x8s will 24inch on center suffice? Don't go 24" OC for a roof that will be sheathed with OSB or it'll sag between joists after a winter.
If 16" on center will 2x6s work ok? Possible, but you'll have to check your local code tables, Rez; I don't have snowload for your area listed in mine plus my AHJ ain't yers....
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
Thanks.
ya, Antique House Journals tend to vary from structure to structure.