Homeowner's Knowledgebase

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September 6, 2017


Roof Maintenance


Is Re-roofing Over Existing Shingles Recommended?

Reroofing over existing shingles is an option considered by many homeowners. Having the existing roof covered with a new set of shingles, opposed to being torn off and then a new roof laid, can help keep costs low and reduce the length of the project; however, is it the best option to ensure quality results.


Issues Can Go Unnoticed

Not all roofing issues are visible from the surface of your roof and if shingles aren’t removed you will never know the full extent of potential damage. For instance, leaks, mold development (which can cause roof rot) and bad flashing are all issues that can be hidden under a roof. It’s during the removal of the current roofing shingles that concerns, such as these, can be revealed and properly repaired.


Two Layers of Shingles Comes With Its Own Issues

In addition to the potential issues that could go undetected, having two layers of roofing shingles poses challenges of its own.  Two layers of shingles mean your roofing structure is basically supporting the weight of two roofs. This can put added stress on the roofing deck. Two layers of shingles also attract much more heat, which can increase the rate at which your shingles deteriorate.

It’s also important to consider how any pre-existing issues with the underlying roof could negatively impact the new roof. For example, algae growth on the original layer of shingles is now placed under the second layer of shingles, which could shorten the lifespan of the new layer as well.


Having your current set of shingles torn off and then re-roofed can be expensive; however, spending the extra money now helps ensure your roof lasts for years to come and additional repairs aren’t required. Here at Turnbull Roofing, our team of roofing professionals can effectively assess the status of your roof to determine the optimal course of action.