Install New Roof Over Old Roof

Installing the new roof.

Install new roof over old roof.

Another concern is that the roof will have added weight if new plywood is installed without removing the old. Inspect the condition of your current roof. 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. Multiple layers of shingles can make it difficult or impossible for the nails to penetrate.

Has the same manufacturer s warranty. A square the equivalent of 100 square feet of three eighths inch plywood the. It can save you money at the time but it might actually end up costing you more in the long run. Installation is easier than for a tear off job because you can use the existing shingles as guides for laying the new ones.

Or if you want to raise the roof a bit more install fascia around the roof perimeter attached to the new soffit and nail the new roof deck to crown molding above the fascia. This means the total roof weight was probably greater when the previous layer of shingles was installed than the new metal roofing. If conditions are right new shingles laid over old shingles can be just as attractive and durable as shingles laid on bare sheathing. One important thing to remember when you re deciding what type of roof to buy is that new asphalt shingles shouldn t be placed on top of old asphalt shingles.

Manufacturers will still warranty the roof for the same amount of time as a re roof as long as it s done by a qualified installer. Roofing over your old roof can save you around 1 000 on installation costs because the roofing company won t have to remove and dispose of old shingles. Looks just as good and lasts as long. That s also why building codes commonly limit re roofing to no more than two layers.

If the job is done correctly with the new layer of shingles laid flat over the existing shingles the old roof cushions the new one and serves as a secondary barrier should wind or water ever break through the new shingles. The condition of the existing roof is critical. Along the rakes install a new j channel drip edge which wraps around the old rake flashing and starter courses. I ll explain why later.

As long as it s done right and under the right conditions installing new shingles over old ones can last as long and look just as good as a complete re roof. Leave the old valley flashing in place and install new over it. The roof should be in sound. To provide a framework for the new trusses nail 2 by 6 inch strips of wood around the perimeter of the roof.

Asphalt over asphalt is not advisable. But you must take care to install shingles correctly so they lie flat. All shingle manufacturers honor the warranty whether their products are used for a reroof or a new roof.