Hello All, I am restoring an 1820’s brick kitchen building with a wood frame roof. The rafters are sawn 3x4x14′ heart pine on approximately 20″ centers. (Black Diamonds?) The roof is 12/12 and currently has 5/8 plywood sheathing with cedar shingles. The plan is to remove shingles and plywood and sheath with t&g v groove 1×6 and then apply a sheet foam approximately 4″ thick with screws and washers and then plywood sheathing and finally cedar shingles again.
I have a few questions being that I have never done this exact operation before.
> Vented or unvented?
>What type of foam?
> Is there a proprietary system that would simplify this. ( I know I could get SIPS with t&g on one side but worried about irregular rafter spacing, 6 3/4″ thickness and lack of access to site for equipment to place them.
>BI has stated that he is satisfied that structure is plenty strong for whatever system I decide to put up there. He just wants a sketch and some specs before I procede.
Any ideas frome the timberframe/ log home guys etc. Thanks for your help. Jay
P.S. I am in Virginia and on a tight time frame.
T
Replies
Greetings Jay,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
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In the event you fail to receive the information you requested you may be able to find it in the achive listing of old threads on Breaktime.
If you scroll up in the upper left corner of your screen there is an advanced search function that will take you to a page of instructions directing you to previous threads dealing with whatever you type in the search bar.
If you type in 'roof venting', 'foam insulation', 'dense cellulose' or other keywords of the subject matter you'll get a supply of data from those old threads.
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One thing I'd do, considering the cedar shingles, is to install Cedar Breather below the shingles. Or 1x skip sheathing over the ply. I'd put 30# tar paper over the ply, and then either the Breather or the 1x battens.
cedar shingles need air space on both sides to be able to dry out and get the maximum life span from them
I would use Dow EPS foam for this, and instead of the plywood, use 1x6 or 1x8 @ 10" OC to create a "cold roof" which solves your venting problem.
Be sure to deal with moisture and cold spots by using tarpaper on the First 1x6T&G cieing before foam, and then make sure to fit the foam tight and use spray foam at seams for ANY irregularity. Do the foam with two plies of 2" and stagger all joints both ways.
If there is any question structurally, you can beef it up better by using 2x6T&G instead of 1x6 for your cieling
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Fellas, I really appreciate your replies and will proceed in that direction. Thanks, Jay