I need some help on this one. I have a customer that has a former summer cottage he purchased last year. He now wants it converted into his all season home. It’s 26′ x 38′ with a 4/12 pitch. The living room is the full 26′ x 15’6″ front facing the lake. This is the problem area. He heated this room last year and had 6″ of ice on the entire roof over the living room. This is a cathedral ceiling with no insulation at all. From interior to exterior, the construction is as follows: 3/4″ cedar, 7/16″ OSB and asphalt shingles. He discovered this problem when he installed a wood stove.
I’m thinking of installing 2 layers of 2″ styrofoam [R-20 total] and OSB and new shingles. Our code here calls for R-40 in ceilings [Manitoba, Canada], but does this qualify as a wall since there would be no air space [like a wall application]. Would I need an air space? Why are timberframes insulated this way [stress-skin panels with no air space] and can anyone see a problem with my method? Does anyone have a better method that they have used with a similar problem. Thanks.
Replies
In BC, a cathedral/shed roof is R28. Are you sure that's not the same for you? Look for a foam with abetter density/thickness/Rvalue ratio, too.
Just what holds up the cedar and osb? Are there joists exposed? Can he insulate between abd lose the cedar?
cheers
***I'm a contractor - but I'm trying to go straight!***
The structure is built with beams running north - south with the cedar running east - west and the osb on top of the cedar. I haven't been on top of the roof yet, but the lines are straight, so it must be fairly strong. There are no rafters at all.
KInd of what I thought. But what abt the insulation that you are going to have to put in? What R-value? Does Hydro have any loans/grants/ assistance there?
Look forward to your solution - or more Qs...cheers
***I'm a contractor - but I'm trying to go straight!***