Posted: 7/6/2011 3:29:27 PM EDT
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I am re-roofing my house; it is a shallow-pitch, 1,300 sq. ft., T&G, cathedral ceiling (you can see the T&G from the inside). I have the old roof(s) completely removed down to the bare T&G (2”x6”). I live in the Central California coastal mountains. It gets pretty cold in winter (and I only have a wood stove for heat), and we can get up to 40 inches of rain per year.
The original roof had two ¾” fiberboard sheets (insulation?), followed by heavy tar-paper covered with rocks. I am trying to figure out if I should put down any kind of insulation. I can get 1&1/2” rigid foam insulation, but I am worried that it will break down as I have to walk a lot on the roof to sweep pine & oak leaves. And the insulation value does not look that much better than plywood. Should I just sheet over the T&G with some ¾” plywood? Or would it be worth it to install the rigid foam? Any input appreciated. |
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Install purlins (2X4, 2X6, etc. Thicker = more insulation.) be sure to nail into existing structure of roof (rafters) so nails do not show through roof deck. Fill spaces between purlins with insulation of choice. Deck roof with plywood. Install roof of choice.
Or you could have a commercial grade flat roof installed with polyisocyanurate insulation board for the desired R value. Not sure about combustibility requirements where you live. A fire rated board may be in order. (Dens deck). Google "built up roof" for more info. YMMV. ETA: I should have been more clear: the flat roof (built up roof) Can be installed without mechanically fastening (screws/nails through roof deck) using asphalt (hot or cold) or adhesive products. |
| Good advice above. You will need 30psi foam board (EPS - Expanded polystyrene) if you want to walk around on it and not leave dents. The typical 1/2" styrofoam insulation sold at home stores is not 30 psi, you will need to go to a roofing distributer like ABC Supply to get that. I would personally use ISO if I could afford it. Oh and while your at a roofing distributer check out the peal and stick base sheet and granulated cap sheet for an easier application. |