Insulating Replacement Wood Shingle Roof
bob2595
| Posted in Energy, Heating & Insulation on
I’m replacing 40 year old wood shingle roof over un-insulated garage and insulated cape. Owner wants to insulate roof (and walls) in garage. Any suggestions about insulation for roof (walls) in garage? I’ll be replacing sheathing too. Appreciate any thoughts or experiences.
Bob 2595
Replies
hot roof (unvented )....or cold roof (vented) ?
will be vented
Build a 2x crib on the roof that stands ½" proud of the insulation thickness (ie: 2x4 on edge for 3" polyiso), lay in your insulation, then screw/nail your skip sheathing to the crib. This will give you both vertical and horizontal air-flow above the insulation and under the new roof deck.
Detail the rake and fascias to create new soffits in both areas which vent to the space under the new roof. I find a cascaded rake and fascia works well to accomplish this, looks nice, and is easy to build onto what's already in place.
There is a new product called 'cedar-breather' or something similar which is intended to be used as a ventilated underlayment for cedar shakes/shingles. I have not used it; you may wish to investigate it. It looks a bit like Scotch-Brite¯ scouring pads.
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