This will help keep any moisture from getting under the felt.
Re shingling a roof over old shingles.
If conditions are right new shingles laid over old shingles can be just as attractive and durable as shingles laid on bare sheathing.
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.
Installation is easier than for a tear off job because you can use the existing shingles as guides for laying the new ones.
If you re going to add a roof on top of an old one it s a good idea to remove any loose shingles and apply a new layer of 30 pound roofing felt before laying the new shingles.
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.
We don t recommend them nor do we do them.
But you must take care to install shingles correctly so they lie flat.
Find a pre screened local roofing contractor.
Install a layer of roofing felt over the roof before you begin installing the new shingles.
If a roof has only one layer of shingles that lay flat and the decking is in good condition a tear off may not be needed.
All shingle manufacturers honor the warranty whether their products are used for a reroof or a new roof.
The layers of felt should be overlapped by 1 inch as you work toward the roof ridge.
Looks just as good and lasts as long.
Has the same manufacturer s warranty.
Installing a new roof over shingles takes less time than tearing off the old roof.
Now everything is trapped under the 2nd layer of shingles again having the potential to shorten the lifespan of the top layer of shingles.
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.
If laying three tab shingles over three tab shingles it is important to nest the new shingles against the old to create a flat surface as friedman elaborates just below.
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.
Most building codes allow for two layers of asphalt shingles on a house so stripping off everything down to the plywood sheathing may not be your only choice.
Roofing over your existing roof is not worth it if you haven t noticed yet we are not fans of shingle overs not at all.
The felt should be secured every six inches with nails or staples.
Not only will the existing layer provide a secondary back up roof for the new shingles but it will also save the cost and inconvenience of removing and disposing or recycling the old shingles.
