Multiple Layer Roofs

Here are the layers of a roof in order of application bottom to top.

Multiple layer roofs.

Adding a second layer could compromise the structure of your roof. We recommend a polypropylene scrim reinforced underlayment made up of multiple layers. Now you just have to decide whether to remove the existing roof shingles or recover the roof. For example towns in climates with heavy hailstorm activity or significant ice dam problems may not allow multiple roofing layers.

One reason some homes have multiple layers of shingles is a homeowner either could not or would not pay to have the original layer of shingles removed after a hail claim. Decking most often made out of plywood this roof layer is installed over the framing in a typical roof install. Having multiple layers of shingles is going to make your roof hotter because the heat gets trapped between the layers which could mean premature aging of the shingles. Benefits of adding multiple shingle layers.

According to the international existing building code homes can be re roofed one time by applying a second layer of roof shingles over the existing one but after that application begins to wear. This type of underlayment is critical to a quality roof installation. This underlayment layer should be of the highest quality. Local codes might not allow re roofing.

That limit pertains to roofs with up to a 4 12 pitch. Many roof decks were designed to handle only one layer of shingles. While simply adding a second or third layer of shingles cost less than replacing the roof my advice to clients is to always have the roof replaced regardless of how long. You can usually see the underside of plywood decking from the attic.

Often there is a problem with the first layer of shingles that was not apparent. When it s time to replace your roof there are several factors that might lead your roofing professional to recommend adding shingles on top of your existing. If the roof is designed to last a lifetime why would anyone want anything but the best. As a listing specialist i am encouraging a roof replacement on our listings that have multiple layers.

This is especially true if you ve overlayed your new shingles on top of warped shingles. A re roof might not look good on an inspection report. But contractors who spoke with angie s list say best practices call for stripping the roof down to the wood deck to inspect it before installing a new roof. It provides structure by tying the trusses and joists together.

Most building codes allow up to two layers of organic or fiberglass asphalt shingles. A second layer of shingles only complicates the job when a roofer is trying to fix a leak. Most cities and towns allow a maximum of two layers of shingles says chad muth president of muth company roofing in westerville ohio.