Can you put shingles over shingles? Here's 8 Reasons why you shouldn't. (2024)

As a homeowner, repairs on your roof are something most people would rather not deal with. However, roof repairs and maintenance can be vital to preserve your home’s integrity and ensure you’re not putting yourself or loved ones in harm’s way.

One of the most asked questions we receive is, “Can you shingle over your existing shingles?” The biggest reason customers ask this question is a simple matter of convenience and cost. Avoiding a tear-off can save customers time and money. However, having multiple layers of protection on your roof can create more problems on its own, costing you even more money down the road.

To answer the question, “Can you roof over an existing roof?” Yes, you can (with asphalt only), but we would never recommend doing so. Below are 8 reasons why we don’t recommend a roof-over.

8 Reasons Not to Put Shingles on Top of Shingles

1. Bumpy Surfaces:

Asphalt shingles are meant to be installed on flat and even surfaces. When new shingles are forced onto bumpy or gap-filled foundations, the old flaps will telegraph through to the new layer, making the top layer much harder to secure. These defects will then telegraph throughout the new layer. This will almost certainly lead to problems later on as the new shingles become more challenging to mount properly and accurately.

2. Improper Inspections:

Leaving the current shingles will prohibit contractors from adequately examining the existing roof’s condition to check if any damaged plywood needs to be repaired first. The plywood could be rotten or even have holes in the wood that need to be replaced to prevent leaks. Without starting from the base, a contractor cannot tell if your home has the correct foundations in place before beginning the project, which could lead to costly repairs in the future.

3. Costly:

In the long run, overlaying can be decidedly more costly than replacement. Saving a thousand dollars from a simple re-roofing may sound appealing now, but the associated costs from a later replacement due to the poor foundation certainly won’t.

Having the old shingles stripped and replaced with layers of new shingles on your existing roof will almost always be more sustainable in the years to come. Besides, every roof gets replaced eventually: by getting a roof-over instead of a full roof replacement, you’ll only be delaying the inevitable disposal fee, not stopping it.

4. Lack of Leak Installation:

Overlaying shingles prevents roofers from properly installing water and ice leak barriers. If you live in an area with brutal winters or other environmental concerns, water leak barriers are essential as they ensure that ice doesn’t leak under the old shingles. Also, by not tearing off the original decking from the existing roof, you are not able to inspect the wood, which could be compromised and cause leaks that are not visible. Simply put, installing new shingles on top of shingles will not repair the current problems, it just covers them up for a short period of time.

5. Weight Strain:

Your roof is most likely built to withstand a specific amount of weight. Small roofs cannot handle immense amounts of additional weight. Adding a second layer to your roof only increases that strain, and can cause further roof problems, especially if the area you live in receives a great deal of snow each year. Even for midsize homes, the addition of another roof’s worth of weight can cause a number of issues once winter arrives, and can even lead to a roof collapse.

6. Warranty Concerns:

One of the main reasons why you should not put new shingles over old shingles without tearing them off is due to warranty concerns. Many manufacturers of asphalt shingles will void the warranty on their product if it is installed over old shingles. This is because the old shingles can cause a number of issues that can affect the performance and lifespan of the new shingles.

It is always a good idea to consult with the manufacturer of the new shingles before beginning a re-roofing project to ensure that you understand their requirements and any potential warranty concerns. By following the manufacturer’s instructions and taking the time to properly prepare the roof for the new shingles, you can ensure that your new roof will be installed correctly and will provide long-lasting protection for your home.

7. Building Regulations:

Specific geographic areas will have guidelines regarding how many roof layers are allowed on buildings. While some building codes may allow re-roofing, others may only allow one layer of shingles. If you live in a location that receives heavy storms, it is important to assess your local code regulations.

8. Future Moving Plans:

If you plan on moving in the near future, re-roofing could decrease your home’s value and make it more difficult to sell. Although re-roofing will not affect the current homeowners, new owners will be forced to tear off two layers of shingles later. For this reason, many home inspectors will report two layer roofs and inform interested buyers about the problems that re-roofing brings with it.

Consult a Roofing Professional

In summary, roofing over an existing roof with asphalt shingles may seem like a convenient and cost-effective solution for roof repairs, but it is not a recommended practice. Putting shingles on top of shingles can lead to a number of problems, including bumpy surfaces, improper inspections, long-term costliness, lack of leak installation, weight strain, warranty concerns, building regulation violations, and decreased energy efficiency.

It is generally better to have the existing shingles stripped and replaced with new layers on the existing roof, which will be more sustainable and effective in the long run. It is important to consult with a professional roofing contractor and carefully consider all options before making a decision about roof repairs.

Hopefully, now you understand why most reputable roofing companies will recommend a roof replacement and won’t consider placing shingles over shingles. A roof replacement is the best practice for your roof’s longevity and for keeping your warranty intact. Protect your most valuable asset and replace your roof the proper way, giving you the peace of mind you deserve for years to come.

If your home is in need of a new roof, contact our experts at Bone Dry Roofing and schedule a complimentary roofing inspection. We are here to help provide clarity and guidance for the roofing solution that works best for your home.