Can You Install a Metal Roof Over Shingles? Benefits & Drawbacks

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Have you considered upgrading your roof but dread the thought of a lengthy, messy installation? You might be surprised to learn that you can install a durable, stylish metal roof directly over your existing shingles. This approach not only streamlines the installation process but also leverages the existing materials for added benefits. Let’s explore whether this innovative roofing strategy is right for you.

So, can you install a metal roof over shingles?

Yes, but under the right conditions. It is crucial that there is only one layer of shingles on your roof. The presence of multiple layers necessitates a complete removal down to the roof deck, inspecting for any damage, and replacing any rotted or damaged sheathing.

How to Ensure a Smooth Installation

To ensure a flawless finish and avoid imperfections showing through the metal, such as bumps or ripples, it is not advisable to lay the metal directly onto the shingles. Instead, a more reliable method involves securing 1×4 wooden purlins over the shingles. These purlins are typically placed 24 inches on center, creating a smooth, solid surface to which the metal can be securely fastened.

Benefits of Installing a Metal Roof Over Shingles

  1. Increased Durability: Metal roofs are known for their longevity and resilience against extreme weather conditions.
  2. Cost Efficiency: By installing over existing shingles, you save on labor and disposal costs associated with tear-off.
  3. Enhanced Insulation: The existing shingle layer acts as an additional layer of insulation and a vapor barrier, potentially improving the building’s energy efficiency.
  4. Quick Installation: The process is generally faster, as the preparatory steps of removing old shingles are eliminated.

Drawbacks to Consider

  1. Potential for Structural Issues: Additional weight from the metal roof might strain older buildings or those not designed to support extra loads.
  2. Limited Conditions: This method is only suitable if there is a single layer of shingles. More than one layer requires a complete tear-off.
  3. Visibility of Imperfections: If not installed with a barrier like 1×4 purlins, any imperfections in the shingles can telegraph through the metal, compromising aesthetic and functional integrity.

Regulatory Considerations

When opting to install a metal roof over shingles, it’s crucial to be aware of local building codes. For residential settings, most regulations will not allow a re-roof over shingles without tearing off down to the decking. However, in commercial applications, if there’s only one prior roofing system, a metal re-roof may be permissible under certain conditions.

When to Take it Down to the Deck

There are situations where removing everything down to the deck is necessary:

  • Presence of multiple roofing layers
  • Signs of significant wear or damage
  • When adding insulation to meet or exceed local codes
  • If inspection reveals wet insulation or extensive leaking

In such cases, stripping to the deck allows for a comprehensive inspection and repair, ensuring the new roofing system is built on a solid foundation, potentially extending the life of your roof with a full warranty.

In Summary

Opting to install a metal roof over shingles can offer numerous benefits, from cost savings to improved durability. However, this option requires careful consideration of your existing roof’s condition and compliance with local codes.

Always consult with a professional to determine the best approach for your specific situation. If you have questions or need further guidance, don’t hesitate to contact us for expert advice.

Kyle Grell

President & Co-Founder

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