Learning Center » Roofing

Can You Put a New Roof on Top of an Old Roof?

Yes, you can put new roof shingles over old ones. However, before you do, consider both the reasons why you shouldn’t do it and the reasons why you should. First things first: adding a new roof over an old (a “re-roof”) is only possible with asphalt shingles. For example, you can’t do it with slate or wood, and you also shouldn’t mix materials. Keep in mind that the old roofing has to be in good condition.

If it’s time for a new shingle roof or a tile roof on your house, you may want to just put a new layer of shingles over the old one. However, this may not always be such a good idea.

Why Installing New Roof Over the Old Roof Can Be Good

  • It’s less expensive. There’s no dumping fee for removing the old roof, and no need for additional felt paper to cover it
  • Less work. The whole procedure certainly takes less time than taking down the old roof.
  • It looks and lasts as good as new, as long as it’s done right.
  • It has the same warranty. The manufacturer’s warranty is still valid, as long as a professional installer does it.
  • It can be an added protection in case a top layer gets blown off in a storm.

As you can see, there are many good things about installing a new roof over the old one, but there are also many times when it might not be a good idea.

When Tearing off the Roof Is a Better Option

There are cases when it’s better (or even necessary) to tear off the old roof and start new. Here are some of these cases:

  • There are already two layers. Most building rules only allow two layers of roofing on your building. So, in this case, the choice is made for you. You need to install a new roof.
  • Existing shingles are in bad shape or curling. The new roof must lay flat on your old one. And if the existing roof is curling, this isn’t possible. You need to remove the old roof.
  • It leaks when it rains. In this case, it’s generally better to remove the old roof so you can find the cause of the problems and fix them. Putting a new roof over a leaking one can not stop the leaks.
  • The roof feels soft and spongy. If you notice these issues when walking on your roof, you may have some problems with the underlying roof sheathing. You’ll need to get rid of the current roof to fix it
  • Your roof can’t handle the weight – They might not seem that heavy, but the shingles necessary to cover a standard 2000 square foot roof can weigh in as much as 5000 pounds, so you need to make sure that the underlying structure of your roof can handle another layer.

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