8 Reasons Not To Put Shingles On Top of Shingles


Deciding on a roof replacement plan can be a tricky proposition for many homeowners. In most situations, roofing contractors will advise a full roof replacement, but in certain circumstances a simpler re-roofing job might be deemed more appropriate. This will be largely dependent on the existing roof’s age and overall quality, as well as from the condition of the house as a whole.

However, when it comes to a re-roof, overlaying shingles has become a method of the past. While a repair job can often be more convenient and somewhat more cost-efficient, placing new shingles over old ones is never a good idea.

Whether repairing one section of roof, or a replacing a whole one, it’s always best to pull up the old shingles before putting down the new ones.

1) Difficulty with Bumpy Surfaces

Shingles are meant to fit flat, even surfaces. When 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. This will almost certainly lead to problems later on as the shingles become more difficult to mount properly and accurately.

2) Improper Inspections

Old shingles prohibit contractors from properly examining the condition of the existing roof. Although re-roofing remains a possibility for homeowners, the presence of the “old” roof prevents roofers from properly inspecting the deck to check if there is any damage plywood that needs to be repaired first.

Without starting from the base, a contractor will be unable to 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 new layers will almost always be more sustainable in the years to come. Besides, every roof gets replaced eventually: by getting a re-roof instead of a full 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.

5) Weight Strain

Small roofs cannot handle immense amounts of 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.

6) Warranty Concerns

Re-roofing can adversely affect the warranty on new shingles. Before any roofing installation, it’s always smart to check with the manufacturer first about the requirements and all warranty concerns to avoid any miscommunications later.

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.

If you are still struggling between re-roofing and roof replacement, you need to contact a professional roof contractor about which path is most beneficial for your home.

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