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  1. #1
    Join Date
    Oct 2008

    Default Old shake roof, spaced roof sheathing, hot attic, poor ventilation, no insulation

    I'm planning ahead for next years' big project and want to kill as many birds with one stone as I can.

    My house has the closed cornice type of roof construction (no eaves). The roof has two asphalt shingles on top of roofing felt on top of cedar shakes. The underlying sheathing consists of one by fours spaced 1-1/2" to 2" apart. Two small gable vents provide the only attic ventilation. There is no insulation.

    First question: Is there a roofing material that could be nailed onto the existing sheathing without sagging into the gaps? Clay tiles, slate, and wooden shakes are out of the question.

    Second question: Is there a sheathing material that could provide some insulation while allowing new roofing to be nailed onto it? I don't want anything much thicker than OSB.

    Third question: Any other advice?

  2. #2
    Join Date
    Jul 2010

    Default Re: Old shake roof, spaced roof sheathing, hot attic, poor ventilation, no insulation

    I don't know if you could kill all your birds with one stone, I know I couldn't.

    1. In my city, and I'm sure everywhere too, your three layers must go. Now, that's a lot of trash.

    2. If one of the layers has asbestos - only certified roofer can remove it and dump it in a legal manner.

    3. Once you are down to the 1x4's check the distance between rafters and their size to see if they are sufficient for a new deck.

    4. If the rafters are OK, you can attach your new deck (OSB or plywood) to the rafters, with or without the 1x4s and your deck is ready for the new roof.

    Insulation: OSB or plywood provide no insulation. It's easy to insulate when the roof is open, so do that. You also need to improve your vents (in your case, look into dome vents).

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