In most areas building codes allow for up to two layers of shingles installed on a roof.
House roof layers.
Underlayment is usually felt or fiberglass paper that covers the entire roof deck.
It should also include the installation of new underlayment such as the 30 pound roofing felt chimney re flashing and ice and water shield at the eaves and valleys of the roof as required by the local building code.
Roll out a single layer of roofing felt or tar paper which serves as a moisture barrier.
It provides structure by tying the trusses and joists together.
Begin this layer at the bottom of the roof and add it in horizontal rows with a slight overlap to prevent.
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.
Like many aspects of a home a roof is fairly complex.
A typical roof replacement quote will normally include the removal and disposal of up to two layers of old shingles.
You can usually see the underside of plywood decking from the attic.
The roof is a system composed of layers of different materials that work together to keep wind and weather out of your home.
The homeowner will have two layers of shingles protecting the roof and the home is less likely to have ice dams he says.
Disadvantages to a roof recover.
On the surface a roof looks like a simple layering of shingles but it s actually much more complex than the average homeowner may realize.
Any more than two layers of shingles can be too much for the roof to handle even if the local building codes don t outlaw it.
There are quite a few parts of a roof on a home including different layers and features.
It s usually a peel and stick product that adheres directly to the roof deck.
If two layers already exist you ll need to remove the old layers before installing a new layer of shingles.
Most often made out of plywood this roof layer is installed over the framing in a typical roof install.
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.
Most roof decking is made from sheets of plywood.
Below we created a very helpful custom diagram that illustrates the various features and layers of a typical roof.