Can You Put A Metal Roof Over Shingles?

Do you want to put a metal roof over your existing shingle roof? This blog post aims to answer a common question: Can you place a metal roof over shingles? We will delve into the world of installing a metal roof over shingles, providing you with a clear understanding of how it can impact your home. So, let's dive in and uncover the exciting possibilities and practical considerations that influence your roofing decisions.

Can You Install a Metal Roof Over Shingles?

The idea of placing a metal roof over existing shingles can be quite appealing for homeowners looking to upgrade their roofing system without the cost and labor of shingle removal. The answer is yes, you can put a metal roof over shingles, but there are critical factors to consider before moving ahead with the project.

Factors To Take Into Account 

1. Roof Inspection: Before proceeding, it's essential to assess the condition of the existing shingles. If they are severely damaged or if there are multiple layers of shingles, it's generally not advisable to install a metal roof over them.

2. Flatness: The existing roof should be relatively flat. Metal roofs can reveal imperfections in the underlying surface, so any irregularities, such as curled shingles, should be addressed.

3. Ventilation and Insulation: Proper ventilation and insulation are vital for preventing moisture buildup and ensuring energy efficiency. Ensure your roof's ventilation and insulation are up to par.

4. Roofing Underlayment: A roofing underlayment should be installed over the shingles to create a barrier and protect against potential moisture issues.

The Drawbacks of Putting a Metal Roof Over Shingles

While the concept of placing a metal roof over existing shingles might seem like a convenient shortcut, there are several compelling reasons why it's generally considered a bad idea.

1. Increased Weight

One of the primary concerns when adding a metal roof over shingles is the increased weight on your roofing structure. Metal roofing systems are heavier than traditional shingles. This added weight can lead to structural issues if your current roof isn't designed to support the extra load. Before proceeding, it's essential to consult a structural engineer to ensure your roof can handle the increased weight without compromising its integrity.

2. Compatibility Issues

Another challenge with putting a metal roof over shingles is compatibility. Metal roofs require a smooth, flat surface for proper installation. Shingles, especially if they are old or damaged, can create an uneven surface, making it challenging to install the metal roofing correctly. Addressing any pre-existing issues with your shingles is crucial to ensure a successful metal roof installation.

3. Difficulty Of Installation

Installing a metal roof over shingles can be a complex process. It typically involves a two-step installation, where the first step is placing wooden strips or battens over the shingles to create a flat surface for the metal roof. This adds both time and labor to the project, making it more intricate and potentially expensive.

4. Trapped Moisture

Moisture can become a significant concern when metal is layered over shingles. Moisture can get trapped between the layers, leading to various issues, including mold and mildew growth, corrosion of the metal, and reduced insulation. Proper insulation and ventilation are crucial to prevent moisture-related problems.

5. Cost

Cost is often a significant consideration when deciding whether to put a metal roof over shingles. While it may appear cost-effective because you avoid the expense of tearing off the old roof, there are hidden costs to consider. The additional materials and labor required for installation over shingles, along with potential structural adjustments, can make this option less economical than it initially seems.

6. Reduced Lifespan

The lifespan of your metal roof can be affected when it's installed over shingles. If the shingles underneath deteriorate, it can compromise the longevity of the metal roofing system. Metal roofs are known for their durability, but this durability depends on the conditions in which they are installed.

7. Warranty Concerns

Metal roofing manufacturers typically offer warranties for their products. However, these warranties may not cover issues arising from the installation of the roof over existing shingles. This can leave you with limited protection in case of problems, so it's crucial to understand the warranty terms and potential limitations before proceeding.

8. Reduced Energy Efficiency

Metal roofs are known for their energy efficiency. However, when installed over shingles, they may not perform as efficiently. The layer of shingles underneath can reduce the reflective properties of the metal, affecting its ability to keep your home cool during hot weather.

Conclusion

The decision to place a metal roof over existing shingles is one that requires careful consideration. We've discussed the potential downsides, including an increase in weight on the roofing structure, compatibility issues, and the risk of trapped moisture, among others. When thinking about this roofing choice, it's essential to compare it with asphalt shingles. At McClellands Contracting and Roofing LLC, we understand the importance of informed choices when it comes to your roofing needs. If you're contemplating a metal roofing project in Pittsburgh, Pennsylvania, we encourage you to reach out to us at (412) 353-5660. Our team of experts are here to provide guidance, assess your unique situation, and help you make the best decision for your home. Your roof is a crucial investment, and we're here to ensure it stands the test of time.