Can You Put New Shingles over Old Shingles?

By Karen L Edwards 09-13-2023
Tag Icon

As a roofing professional, you likely field questions from curious homeowners from time to time. One of the trickier questions—because there isn't a definitive answer—is: "Can you put new shingles over old shingles?" The answer to this will depend on certain factors, and you can only provide a firm "yes" or "no" after inspecting an individual's roof.

So the short answer is: yes, it's possible to install new roof shingles on top of existing ones. But . . . specific conditions must be met and the following considerations must be taken into account:

Local Codes and Roof Condition Considerations

First, you need to understand your local building codes. In most jurisdictions, the code won't allow more than two layers of roofing on a home. If the home already has two layers, a complete tear-off is in order. If it has only one existing layer, the roof may be a candidate for a second layer.

The existing roof's condition will also help determine if a shingle-over-shingle installation is possible. If shingles are weathered, warped, or curling, they aren't suitable to be shingled over. New shingles require a smooth surface for proper installation and performance.

Also, consider whether the homeowner is replacing the roof because they've experienced extensive leaking. In this case, putting new shingles over the existing ones may not be wise. Water damage to the deck or mold issues might be left untreated if they remain hidden under the existing roof.

Risks of Putting New Shingles over Old Ones

A shingle over shingle installation can be appealing to homeowners due to lower costs and faster installation time. But it's important they understand the potential risks. For instance, you'll likely have to explain that a roofing system is composed of many parts that work together to provide protection for their home. Many homeowners think of a roof as only what they can visibly see—the shingles.

GAF brochures can help with the education process. For example, the GAF Timberline HDZ® brochure includes diagrams that identify each layer of the roofing system, which can help homeowners understand how each one is necessary to achieve a roof's peak performance.

Benefits of a Tear-Off and Replacement

The next time you're asked, "Can you put new shingles over old shingles?" you'll be able to respond with some solid answers about the pros and cons. To give the homeowner a complete picture, you should also share the benefits of a complete tear-off and replacement, so they can understand their options and make a cost-benefit calculation.

Here's a look at a few advantages a total replacement offers:

  • A tear-off allows the contractor to inspect the wood deck's condition and determine if repairs or new OSB board are needed to ensure it's structurally sound.
  • Tearing off the roof's old layers can help ensure the new system has a solid, smooth surface for optimal performance.
  • A total replacement allows an adequate leak barrier to be installed in critical areas, including rakes, eaves, valleys, hips, and around penetrations.

As a contractor, it's important to guide the homeowner through their decision-making process to help them find the best solution for their individual circumstances. To gain access to the tools, trainings, and resources that make this easier and to offer enhanced warranty systems to your customers, become a GAF-certified contractor.

Don't miss another GAF RoofViews post!
The arrival of autumn means brisk temperatures and falling leaves. You might spend time raking those leaves in your yard—but did you know it's also important to remove leaves from a roof? If left on the roof throughout the winter season, those beautiful, color-changing leaves can potentially cause some serious problems, similar to issues moss buildup poses. Here are the key details to know.
Aromatic logs, the orange glow of flames, and the heat emanating from a fireplace can make even the coldest winter days more tolerable. Preparing your fireplace for winter is imperative to ensure that it performs efficiently and safely throughout the cold season and beyond. Here are some tips for preparing a fireplace and chimney for winter so it can provide the comfort you desire during the cold months.
As part of the nation's longstanding tradition of honoring people who have served in the armed forces, a new museum has been built to recognize those who have been awarded the highest military decoration, the Medal of Honor. GAF is proud to be playing a role in the Gainesville Medal of Honor Museum and Education Center in Texas, set to open its doors in 2024.
One high-stress area of a residential roof is where its two faces meet, either at a hip or a ridge. Protecting these areas helps reduce the risk of leaks. Before the advent of shingles purpose-made for hip and ridge caps, roofers typically cut up 3-tab strip shingles and bent them over these areas of the roof. Today, specially made versions of these types of shingles provide better protection while maintaining a roof's aesthetic appeal.
Buildings are designed to keep the outside weather out and the inside space conditioned as the occupants desire. A building's enclosure or envelope is made up of multiple layers of materials with the goal of stopping the uncontrolled movement of water, air, heat, and moisture vapor.
Work is getting underway in Greater Charlotte, North Carolina, as GAF supports Habitat for Humanity with the 2023 Jimmy and Rosalynn Carter Work Project. The five-day build event began in 1984 when former President Jimmy Carter and former first lady Rosalyn Carter led a group of Habitat for Humanity volunteers to New York, building alongside 19 families in need of safe, affordable housing. For 36 years, the Carters have worked side by side with professional builders and volunteers at locations around the world to build and raise awareness of affordable housing.
This blog contains information created by a variety of sources, including internal and third party writers. The opinions and views expressed do not necessarily represent those of GAF. The content is for informational purposes only. It is not intended to constitute financial, accounting, tax or legal advice. GAF does not guarantee the accuracy, reliability, and completeness of the information. In no event shall GAF be held responsible or liable for errors or omissions in the content or for the results, damages or losses caused by or in connection with the use of or reliance on the content.

Interested in sharing or republishing our content? We kindly ask you to adhere to our guidelines.