When it’s time to replace your asphalt shingle roof, the first thing you’ll need to do is find a few trusted roofers in your community and get written estimates. You might discover that some roofers would prefer to install the new roof over the existing one while others recommend stripping off the old shingles before installing the new ones. The cost difference can be in the hundreds leaving you wondering which you should choose. Here are some things you’ll want to keep in mind when making your decision.

Two layers of roof shingles meets two times the weight. Many homes, especially older ones, might not be built to support that much weight. Add to that the weight of snow in the winter and you’ve got a huge structural concern if your home can’t hold the weight. In addition to the age of your home, another factor that will help you determine whether two layers will be too much weight is the pitch of your roof. Low sloped roofs have to support more weight that a steeply pitched roof. So if your home is newer or has a steeper pitch, installing a second layer of shingles could be a feasible option.

Life expectancy

An asphalt shingle roof will typically last around 15 years. If you install as asphalt shingle roof on top of older shingles, you decrease the lifespan of that roof. That’s because of the ventilation from the attic and heat becoming trapped between old and new shingles wearing out the new shingles more quickly. If your old roof shingles were becoming warped and curled, then that might be visible through your new shingles and will diminish the look of your new roof. If your old roof is in decent condition and you’re planning on moving in a few years anyways, you might still consider installing the second layer of shingles on top of the first.


When replacing your roof, the cost of removing the old shingles is factored in. That’s why you’ll see a lower estimate when the roofer wants to install shingles on top of your existing ones. But because you’ll likely get less life out of your new roof when it’s installed on top of another layer of shingles, and because you’ll have to pay to remove two layers of shingles the next time you replace your roof, the savings probably aren’t going to be worth it in the long run.

The bottom line

Most roofers recommend removing the old shingles first, regardless of the condition of the existing shingles and the pitch of the roof. If there are any problems with the roof deck, the removal of old shingles will reveal them so they can be repaired prior to the new roof being installed. Your new roof will look better and last longer.

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Source: thespec .com/living-story/6077134-should-roof-shingles-be-replaced