My insurance company is requiring that I replace the 40-year-old shake roof on my Tahoe A-Frame cabin (i.e., heavy snow load!) with something fire-resistant. My question relates to water vapor condensation. The current roof is made of 4 X 12 rafters on 4 foot centers with 2 X 6 tongue & groove decking. On top of the T & G is 1″ fiber board insulation overlaid with felt paper and cedar shakes. No vapor barrier, no other insulation, no ceiling other than the T & G. When I installed several skylights a few years ago I noticed no signs of condensation, so I know the old shake roof breathes well. I can’t afford to reconstruct the roof to provide the ideal of vapor barrier, insulation and venting, so I’m wondering what is the best fire-resistant replacement for the shakes? Metal will create condensation and rot the roof, and composition shingles won’t nail on top of the relatively soft fiberboard. I’ve heard of products like Eco Shake that are fire-resistant, but will it breathe and prevent condensation? Any ideas?
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Greetings BorgT, As a first time poster Welcome to Breaktime. Sorry for the time lag.
If you haven't received an answer to your query, this post, in response to your question, will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someones attention that can help you with advice.
Cheers
Thanks for bringing my message back into the thread. Got a couple responses worth ruminating on... Much appreciated.
How about nailing 1X4 sleepers over the fiber board, then fastening steel to the sleepers? Put in continuous ridge vent and also vent the eaves.
Thanks for the idea. I'm going to give it and the other one that came through to a roofing contactor and see what comes from it. Appreciate the help.
"I can't afford to reconstruct the roof to provide ..."
I can understand the headache of the ins CO forcing your hand, but if you have to replace anyway - there is a way you CAN aford this deal. hope I don't sound like a shyster with that line....
but you already have to strip the roof. Once open, you add three or four inches of Dow faom, sealing the edges with spray foam. Then add horizontal sleepers/purlins screwed through to the 2x6T&G. Then roof aver that. The savings in energy cost will pay for that upgrade in three years and keep puting money in your pocket forever after that.
Type of roofing? whatever you want. metal direct on sleepers at 24" OC.
Fireproof shakes same except at ten inches OC.
Comp shingles - add plywood sheathing first
Trim edges with made up sheet metal trim
Condensation? If you see no sign, there must be a reason. I bet there is a MS or VB over the T&G and under the panel now. The new - the Foam works effectively as a VB
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Good ideas! I like the concept of adding foam insulation, but I'm not sure how difficult it would be to raise my nine skylights. I'm going to get a roofing contractor to give me input and will give him your thoughts. There is no vapor barrier at all - this I know from installing seven of the skylights years ago - and no condensation either. Only thing I can think is that the old shake roof is like a sieve and lets everything through. Thanks again.
There are several fireproof composite or metal immitation shakes available, or at least they were about ten years ago. Specifically designed for areas where wood shakes are a fire liability.