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Should You Put a Second Roofing Layer Over an Existing Roof?

Should You Put a Second Roofing Layer Over an Existing Roof?

While roofs last for years, they eventually do need to be replaced. There are several options for homeowners who are looking to replace their roof. Roof overlays and complete roof replacements are the two most common options.

What is a Roof Overlay vs. Complete Roof Replacement

A roof overlay is the process of adding a layer of shingles over a preexisting roof. This can only be done if it is the first time an overlay has been installed. The process is quick and affordable as the cost of labor and materials is less than other replacement methods. Homeowners that choose a roof overlay are often interested in the lower cost as compared to a complete roof replacement. A complete roof replacement removes the existing roof and replaces it with new materials. This allows for any roof issues to be completely addressed. While an overlay is less expensive than a tear-off, it will not provide the same level of durability as a new roof, nor will it increase the resale value of the home.

Roof Overlay Issues

While a roof overlay saves on time and money, there are several drawbacks that must be considered:

Structure: Adding a new layer of shingles over the existing roof can cause strain and stress on the roof from the added weight. For older homes, this can cause significant structural damage. The overlay cannot fix any problems that the roof may have so the new roof will only look as good as the old one did. Shingles should be installed on flat and even surfaces. When new shingles are forced onto bumpy surfaces, dips or curves in the previous shingles will dictate the shape of the new shingles. The second layer is difficult to mount properly on a roof that is not flat and even and can only be mounted on three-tab shingles, not dimensional or architectural ones.

Damage Remediation: When the entire roof is removed, the roofers have the ability to examine the roofing deck to look for leaks or rots. These can be fixed before the new roof is installed. This is not possible with an overlay which can mask problems. If there is a leak in the roof it can be difficult to identify. Trapped water can migrate making repairs an ongoing issue. The second layer of shingles trap heat which can decompose both layers of shingles. The extra layer can reduce the lifespan of the roof significantly.

Home Inspection: Because the shingles go over the existing roof, the condition of the roof cannot be assessed or repaired. A contractor will not be able to tell if the home has the correct foundations in place which can cause costly repairs in the future. In the long run, this can be more costly than a complete replacement.

Leaking: Roofers cannot install water and ice leak barriers without doing a complete roof replacement. If the home is located in an area with harsh winters, water leak barriers are necessary, so ice does not leak under the old roof. Moisture can get trapped under the layers and cause premature aging to the wood.

Warranty: Manufacturers of shingles will often void the warranty on their products if installed over old shingles because this process can affect the lifespan of the new shingles. Certain areas have building codes that do not allow for a double layer of shingles.

Hidden Costs: Both layers of the roof will need to be removed when the roof is replaced the next time. The cost for a double tear-off is usually more than just a single layer because it is double the labor to do the removal and double the price for removal.

Lower Resale Value: A roof overlay as a replacement choice can negatively affect the resale value of your house. Homeowners will not want to have to replace the roof right away, and with a roof overlay, it is uncertain how long it might last. Home inspectors will often leave a negative mark on the inspection report for a roof overlay which can reduce the value of the home.

Complete Roof Replacement Benefits

A tear-off roofing project ensures that the roof will last longer and is of higher quality. A complete replacement allows the homeowner to choose a more modern and potentially stronger roofing material, allowing it to withstand tough weather. A replacement lasts longer because the old roof shingles are removed and replaced with new ones. The new shingles do not trap as much heat so they last longer. A brand-new roof on a home increases the value of the home, where as an overlay can be viewed as a detriment to a potential buyer because it will have to be replaced most likely sooner rather than later.

Because the entire roof is being replaced, the cost of a total roof replacement is more than an overlay. The cost will vary on the size of the roof, type of shingle, as well as the type of materials used. The higher quality materials, the higher the cost. However, the investment in a properly installed new roof by a professional will last for decades.

Get a Professional Opinion With J.A.Y. Construction

While layering shingles on top of old ones is a convenient solution to refresh a roof, it most likely is not a viable solution in the long run and may even create more damage to the home’s structure and shorten the roof’s lifespan. There are many options when you choose to replace your roof. J.A.Y. Construction can work with you from start to finish to find the best roofing options for your home. Our roofing experts will provide guidance when it comes to replacing your roof.