Installing New Roof Over Old

A properly installed layover roof can look and function as well.

Installing new roof over old.

Installation is easier than for a tear off job because you can use the existing shingles as guides for laying the new ones. 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. That s also why building codes commonly limit re roofing to no more than two layers. Has the same manufacturer s warranty.

Installing a new roof over an existing one also called a layover or nailover is often possible although not always the best option. Looks just as good and lasts as long. Leave the old valley flashing in place and install new over it. 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.

But you must take care to install shingles correctly so they lie flat. 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. To level out an existing asphalt shingle roof rip down reduce the height of two courses of shingles as shown in the drawing below.