New Roof Installed Over Existing Roof

One affordable method of re-roofing a home is to install a new layer of shingles over the existing ones. This method can be a cost-effective answer to a homeowner’s roofing needs because it saves the expense of a tear-off of the old roof. However, this method has its pros and cons and is not appropriate for every home.

The existing roof has a lot to do with whether or not another layer of shingles is an appropriate solution. Most importantly, re-layering shingles over existing ones can only be done for roofs that are already roofed with asphalt shingles. Wood shakes, slate, tile or metal roofs are not candidates for layered-roofing strategies.

In order to successfully add another layer of asphalt shingles, no more than two layers can already exist on the roof. This is because most building codes allow only three layers of shingles to be installed on any roof. Some areas permit no more than two layers.

No matter how many layers of shingles are already on the house, before installing another set of shingles, Middlesex county roofers must assess the ability of the existing roof to support the weight of an additional layer of shingles. If the roof trusses and decking cannot support the extra weight, installing another layer of shingles could cause disaster to arrive along with the first heavy snow of the season.

No homeowner wants to risk a roof collapse, no matter how much of a bargain a re-layering of shingles appears to be.

Only a roof that is in good repair is a good candidate for installing a new layer of shingles over an existing one. Small problems can be fixed before installing the new layer of shingles to provide a roof that will protect the home for the duration of its warranty. Installing more shingles on a roof that has been poorly maintained and leaks in several places is a waste of time and money and invariably leads to more expensive repairs in the very near future.

There is an art to installing a new roof over an existing one. Only roofers who are skilled in this type of procedure should attempt it. Installing flashing for vents and chimneys on layered roofs takes special training, and there are tricks that only skilled roofers know when it comes to installing new shingles over existing ones so they don’t crack or curl. Homeowners who wish to install a new roof over an existing one should select only roofers who have experience in this technique. The roofers at Fortified Roofing of Middlesex County NJ can answer your questions regarding new roofs or skylights.

Term from the roofers at Fortified Roofing, Middlesex County NJ:


The process of completely removing the existing roofing materials before installing a new roof is called a tear-off. All of the old materials, including flashing, tar paper and shingles, are removed. This allows the decking to be inspected and repaired as necessary before the new roof is installed.

Middlesex County roofers Fortified Roofing answers a common question:

Does installing a new roof over an existing roof affect the new roof’s performance?

Installing a new layer of shingles over an existing one does not necessarily affect the performance of the new roof. Shingles installed in layers build up and release heat differently than those installed as a single layer, which could affect the shingles’ longevity. However, for attics that are properly ventilated, the effect is much less than on roofs whose attics are too hot and moist.

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