Problems With Installing a Metal Roof Over Your Shingles

April 30, 2023

Metal roofs can offer many benefits to homeowners, such as energy efficiency, cost savings and moisture resistance. It may be tempting to save some money by installing a metal roof over your current shingle roof, but when metal sheets are placed over shingles, some of the benefits metal roofing brings may be canceled out.

1. Decreased Roof Life Span

When a roofing company performs a roof replacement, they look at the roof’s decking which is an important part of the installing a roof. They should look for existing problems and correct issues so the new roof system has a secure foundation.

Putting a metal roof over shingles cuts out the decking inspection step since the shingles remain in place instead of being removed. Skipping a decking inspection means you and your roofing contractor miss the chance to replace any rotted or unstable roofing materials. If your roof has any issues that go unnoticed, these could lead to structural damage and put you and your family at risk.

Metal roofs are designed to be durable and long-lasting, but installing them over shingles can affect their life span. They may only last for a short time due to problems with your old roof and may need to be removed eventually to address issues.

2. Increased Moisture Issues

One of the benefits of a metal roof is its moisture resistance. The durable sheets can withstand storm damage that could lead to punctures and water leaks, and the underlayment can provide extra protection for your home.

Placing a metal roof over shingles can cancel out its moisture-resistant benefits, though. Without proper ventilation between the roofs, water vapor can get trapped inside and begin degrading the shingles. Excess water can facilitate mold and mildew growth, increasing health and safety risks.

3. Escalated Expenses

Installing a metal roof over your shingles may save you some money at first, but if there are any current issues with your shingle roof, you could experience greater expenses in the future. Placing a new roof on top of your old one will not solve problems but could eventually make them worse.

If your roof is experiencing leaks, they will continue even after a new metal roof is placed on top. Your roofing contractor will then have to thoroughly inspect both roofs to discover where the leak is coming from and what kind of repair it needs. There are other problems with finding roof leaks when a metal roof is installed over an existing shingle roof. Due to having two or more roof surfaces, a leak may start at one point, then travel and enter your home some place else.

Replacing a roof completely allows you and your roofing company to evaluate various roofing components and replace damaged or old areas. When you install a metal roof on your old one, you miss the chance to update materials and ensure your roof’s safety and longevity.

4. Missed Code Compliance

Local and state building codes are designed to protect homeowners, their families and their properties from damage and harm. Regulations may differ from place to place, so if you are considering doing work on your roof, review your local building codes to ensure you remain compliant and safe.

Many regulations specify whether homeowners must remove existing roof layers before replacing their roofs. Homeowners who do not comply with codes and choose to install metal over a shingle roof may create problem for themselves in the future. If your roof is not compliant with building codes, you may need to replace it entirely, leading to even more costly replacements and repairs.

Some codes also state that the new roofing material cannot be heavier than what the roof and house can support. Metal roofing is a relatively light material, but if your previous roof was already heavy, adding more weight on top may put excess stress on your home’s structural support.

5. Voided Warranty

Metal roof manufacturer warranties are some of the best since the material is durable and has a long-lasting life span. Many warranties contain stipulations and terms stating the metal roof cannot be placed over an existing roofing layer. If you install your metal roof over shingles, you may be left without coverage for your new roof.

Read your warranty thoroughly to understand what is and isn’t allowed so you can enjoy all the benefits of your new metal roof and its coverage, including:

  • Protection for your home.
  • Replacements for roof components.
  • Assurance of proper installation.
  • Cost savings.

Call RoofAid USA for Help Installing a New Metal Roof

At RoofAid USA, we care about the stability and security of your roof and home. Our experienced professionals will provide the services you need to enjoy all the benefits of a new metal roof while reducing any metal roof over shingles problems. Invest in a quality roof replacement by requesting your quote today!