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I am in the process of renovating the roof of a sixty year old vertical-log cabin in the Upper Peninsula of Michigan. The construction method for the current roof has 16″ on-center 6″ diameter log rafters from the roof ridge to the roof edge, spanning a distance of about 20′. The top surface of the rafter has been “flattened” and topped with 1″ thick, 6″ wide T&G pine boards forming the inside ceiling. On top of the pine is tar paper, then 1″ of white-colored foam-bead board. covering the foam is more tar paper then 1/2″ of plywood, more tar paper, then two layers of shingles on top of the original shingles.
Over the years, the roof has aged, matured, or otherwise changed from a flat surface to one of smooth bends and dips. I would like to (1) add more insulation and (2)restore the roof to a flat surface.
First, after removing all shingles, et all, down to the plywood layer, I am contemplating attaching 2X4’s on edge centered above the log rafters, shimming as necessary to restore a flat surface.
Second,I would install either blue styrofoam or celotex (black side out/foil side in) in between and one layer above the 2X4’s. Then, install plywood and the shingle or metal roofing materials.
Most people I have talked to about this, have indicated I must have an air-space between the insulation and the plywood/shingle materials. However, my searches have indicated if one uses a continuous closed-cell foam and glue/seal the edges and the plywood to the top of the foam…no air space is required.
If you could shed some light on my situation, I would appreciate any comment/correction you could provide.
Thanks
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I am in the process of renovating the roof of a sixty year old vertical-log cabin in the Upper Peninsula of Michigan. The construction method for the current roof has 16" on-center 6" diameter log rafters from the roof ridge to the roof edge, spanning a distance of about 20'. The top surface of the rafter has been "flattened" and topped with 1" thick, 6" wide T&G pine boards forming the inside ceiling. On top of the pine is tar paper, then 1" of white-colored foam-bead board. covering the foam is more tar paper then 1/2" of plywood, more tar paper, then two layers of shingles on top of the original shingles.
Over the years, the roof has aged, matured, or otherwise changed from a flat surface to one of smooth bends and dips. I would like to (1) add more insulation and (2)restore the roof to a flat surface.
First, after removing all shingles, et all, down to the plywood layer, I am contemplating attaching 2X4's on edge centered above the log rafters, shimming as necessary to restore a flat surface.
Second,I would install either blue styrofoam or celotex (black side out/foil side in) in between and one layer above the 2X4's. Then, install plywood and the shingle or metal roofing materials.
Most people I have talked to about this, have indicated I must have an air-space between the insulation and the plywood/shingle materials. However, my searches have indicated if one uses a continuous closed-cell foam and glue/seal the edges and the plywood to the top of the foam...no air space is required.
If you could shed some light on my situation, I would appreciate any comment/correction you could provide.
Thanks