Top Reasons Why You Shouldn’t Layer Asphalt Shingles Over an Existing Roof

by Amy


Layering asphalt shingle roofing has been a way to save time and a little bit of money when you need to replace your roof.


However, layering roofing can:

  • Void your shingle warranty.
  • Add excessive weight to the structure of your house.
  • Diminish the overall life of the roof.

Before considering layering roofing over an existing roof, it’s important to check your local building codes. Many restrict a number of times you can layer the roofing.

So chances are if your roof already has more than one layer of roofing, you’re ineligible.

If you only have a single layer of roofing currently, and your home is fairly new, structurally the home will probably withstand the extra weight.

However, I’ve seen older homes that experience severe settling after a second roof is added over the first.

I’ve also seen roofs that are made ineligible for layered roofing because the warping and cupping of the existing roof would damage the new shingles.


The Importance Of Quality Roof Shingles

The biggest mistake people make when layering roofing is to purchase cheap shingles for the new roof. They seldom consider that in 15 years, when their roofing once again fails, they will have to pay significantly more to have someone remove both layers of shingles and apply new ones.

Savvy homeowners (or at least their home inspectors) are aware of this fact and may balk at buying a layered roof. Home inspectors are also aware that the thicker the roof, the less hold the roofing nails have in the sheathing. In a high wind situation, this can mean the difference between the shingles staying on, or being pulled off the roof.


Does Layering Roofing Shingles Fix Leaks?

One misconception is that layering roofing will eliminate old roof leaks.

Although this sometimes occurs, it is my experience that an unexplained leak will eventually reappear — even after new roofing is applied.

For this reason, you should fix any problems with your old roof and be sure to address any leaks before starting a new roof.

Want to know the best way to test for leaks? Check out this expert advice.


Does Layering Roof Shingles Save Money?

Most people want to add another layer to their existing roof to save money.

However, this is a particularly short-sighted approach, once you realize that layering roofing can often void the warranty.

Manufacturers believe that layering the roofing diminishes the overall performance of the roof. Ignore their advice and you’ll find your 50-year warranty worthless!

If the manufacturer claims to not have a policy against layering, get something in writing from the company that promises your warranty will not be voided if there is a problem.

Adding another layer of asphalt shingles over existing roof shingles. photo by waitscm on Flickr


Don’t Skimp On A Cheap Roof Job

While there are many places to cut corners in home maintenance, replacing a roof should never be something you do on the cheap.

A bad roof can be the source of extensive and expensive problems that can severely diminish the value of your home.

Instead, try to buy the best roofing you can afford and be sure to budget a little extra — so the old roofing comes off before the new shingles go on.


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