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Can You Put a New Roof Over an Old Roof?

roofing problems

It’s not uncommon to see a new roof being installed over an old one. In fact, in some cases, it may be the only option. But is it really a good idea? This depends on the age of the existing roof and its quality.

In the past, overlaying shingles was a common method for repairing roofs. However, this is no longer a recommended practice. Although repairs may be more convenient and less expensive, laying new shingles over old ones will never produce optimal results.

When fixing a roof – be it one area or the whole thing – always start by taking off the old shingles before adding new ones. Here are some reasons why you should not install a new roof over an old one:

Weight Strain

The additional weight of the new shingles will put extra stress on the existing roof structure, which may not be able to support it. This could lead to collapse.

A small roof can collapse under too much weight, and adding a second layer of shingles puts even more strain on the supporting structure. If you live in an area with heavy winter snowfall, this is particularly dangerous.

Water damages

One of the primary functions of shingles is to keep water out. When you install new shingles over old ones, you create seams and valleys where water can seep through.

These leaks may not be immediately apparent, but over time, they will cause extensive damage to your home, including mold and rot.

Building Regulations

Depending on your location, there will be restrictions on how many layers of roofing you’re allowed to have. Some counties may allow for re-roofing while others only permit a single layer. If you reside in an area with severe weather conditions, it is crucial to evaluate your town or city’s code regulations.

Poor Aesthetics

Putting a new roof over an old one will not produce a uniform look. The new shingles will be a different color and texture from the old ones, which will give your roof an unattractive patchwork appearance.

Limited Warranty

Many roofing manufacturers will void the warranty if you install new shingles over old ones. So, if there are any problems with the new shingles, you will have to pay for the repairs out of pocket.

It’s always best to start from scratch when you’re repairing or replacing your roof. Although it may be more expensive and time-consuming, it will produce better results in the long run.

Improper Inspections

When there are old shingles present, contractors can’t get a good look at the roof to determine if it needs to be replaced. Although re-roofing is still an option for homeowners, they won’t know if any damage has been done to the plywood beneath the shingles until all of the old material has been removed.

If a contractor does not start from the beginning, they will be unable to discern if your home has the right foundations. If this is ignored, it could result in expensive repairs down the line.

Problems with Uneven Surfaces

Shingles work best on even, level surfaces. If you have to fit them onto a bumpy or gap-filled foundation, the old flaps will show through to the new layer and make it harder to secure. This will likely create problems down the road as the shingles become harder to mount with precision.


It’s best not to install a new roof over an old one. Although it may be more convenient, it will never produce optimal results. If you’re not sure whether to repair or replace your roof, consult with a professional roofing contractor. They will be able to assess the condition of your roof and advise you on the best course of action.