New Roof Sheathing Over Old

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New roof sheathing over old.

Roy gingrich of ellicott city has a 40 year old house with an asphalt shingle roof surface. Nailing new shingles over existing ones is less expensive and faster requiring less labor but it also means you lose the chance to assess the sheathing for signs of water damage. If conditions are right new shingles laid over old shingles can be just as attractive and durable as shingles laid on bare sheathing. Has the same manufacturer s warranty.

Answered 6 years ago by wowhomesolutions. If your roof is in good shape but has some damage to one side from a downed tree or has lost shingles in a wind storm an overlay is worth considering. Installing new roof shingles over old effectively doubles the weight of the roofing so you have to make sure your roof structure can handle the extra load. That s also why building codes commonly limit re roofing to no more than two layers.

The new plywood thickness should be. The existing asphalt shingles need replacement so he plans to do a tear off and re shingle. Looks just as good and lasts as long. As long as the new plywood itself can span the distance and carry the roof wind seismic and snow loads for your region adding new ply over old is just fine.

That must always be accounted for in the roofing design process. Going over inadequate thickness plywood for a more solid deck or skip sheathing is fine as long as they pay special note to the ventilation and home the roof is designed to vent. Installing a new roof over shingles takes less time than tearing off the old roof. But you must take care to install shingles correctly so they lie flat.