Would you guys take a look at the post that I posted late last night under the User Name DonnieB. I mentioned issues that I am having getting my roof redone and I got 1 response from Happy Face with the shades, which I appreciate. 20 guys respond to what’s wrong with this ridge vent when all you have to do is read the instructions and you will know what’s wrong with it. I list problems that requires a little creativity and nothing. If my roofer rips off the roof decking and replaces the insulation in the batt of a 2x10 ceiling, how would you insulate and vent? The problem is he is working from the top down. Do you guys use the Corning dense pack for this kind of ceiling and how would you get the vent to line up or stay in place? I haven’t heard a good solution yet. If I get one that make sense I’ll send you a little reward. Owens couldn’t offer a solution, I’m sure you have had this problem before. What do you use for plywood when the roof needs to be replaced. Fir? Too expensive? What thickness? Where are you guys?
2# closed cell polyurethane foam insulation will give you and R6 per aged inch, and can be sprayed into the cavity so at to leave an air space on the underside of the roof deck for ventilation, since he is already pulling the roof deck.
What’s the prize?
I spoke to Anderson Insulation who uses a similar product on This Old House. He said he wouldn’t do it from the outside in, the ceiling could be damaged when the product expands. He wanted me to rip the ceiling off and spray from the inside. So I think, close but no cigar. I really don’t know what the best solution is. I would have hoped some of you had a similar problem and came up with a clever solution.
As AaronB. Stated the urethane spay will give you the proper cavity for ventilation. You will need to install a vapor barrier and that will protect your ceiling. If you spray from the inside against the under side of your decking this will probably take away your vent space as you want the venting area over the insulation.
In Alaska it is very common to insulate the way Aaron described.