Metal roof over shingles problems

Metal roofing has gained popularity in recent years due to its durability, energy efficiency, and aesthetic appeal. However, for homeowners considering installing a metal roof over existing shingles, there may be concerns and potential issues to address. In this comprehensive guide, we’ll explore common problems associated with installing a metal roof over shingles and provide actionable solutions to ensure a successful roofing project.

Roofing Material Compatibility:

One of the primary concerns when installing a metal roof over shingles is ensuring compatibility between the two materials. Different types of shingles, such as asphalt, wood, or composite, may have varying levels of compatibility with metal roofing systems. Improper compatibility can lead to issues such as uneven surfaces, poor adhesion, and premature deterioration.

Solution: Before proceeding with the installation, consult with a qualified roofing contractor to assess the compatibility of your existing shingles with the chosen metal roofing system. In some cases, it may be necessary to remove the old shingles to ensure a smooth and even surface for the metal roof installation.

Moisture Trapping and Ventilation:

Moisture trapped between the old shingles and the new metal roofs can lead to a range of problems, including mold growth, rot, and structural damage. Proper ventilation is essential to allow moisture to escape and prevent it from accumulating beneath the metal roofing.

Solution: Incorporate effective ventilation systems, such as ridge vents, soffit vents, or attic fans, to promote airflow and prevent moisture buildup. Additionally, consider installing a breathable underlayment between the old shingles and the metal roof to provide an extra layer of protection against moisture intrusion.

Weight Considerations of metal roof:

Adding a metal roof over existing shingles increases the overall weight load on the roof structure. While metal roofing is generally lighter than traditional roofing materials, the additional weight can still pose a concern, especially for older or structurally compromised roofs.

Solution: Before proceeding with the installation, have a structural engineer assess the load-bearing capacity of the roof and ensure it can support the weight of the new metal roofing system. Reinforcements may be necessary to strengthen the roof structure and prevent sagging or collapse.

Heat Retention and Energy Efficiency of metal roof:

Metal roofs have excellent reflective properties that help reduce heat absorption and lower energy costs. However, when installed over shingles, the airspace between the two layers can diminish the metal roofing’s energy-efficient benefits.

Solution: Consider installing a radiant barrier or reflective insulation beneath the metal roof to enhance its energy efficiency. These additional measures can help minimize heat transfer and improve the overall thermal performance of the roofing system.

Warranty and Insurance Considerations:

Installing a metal roof over existing shingles may void the warranty of both the metal roofing manufacturer and the shingle manufacturer. Additionally, some insurance providers may have specific requirements or restrictions regarding roof overlays.

Solution: Before proceeding with the installation, review the warranty terms and conditions provided by the metal roofing manufacturer and consult with your insurance provider to ensure compliance with their requirements. It may be necessary to obtain written approval or documentation to maintain warranty coverage and insurance benefits.


While installing a metal roof over existing shingles offers numerous benefits, it’s essential to address potential problems and concerns to ensure a successful roofing project. By considering factors such as roofing material compatibility, moisture trapping, weight considerations, energy efficiency, warranty, and insurance implications, homeowners can make informed decisions and mitigate risks associated with metal roof overlays. With proper planning, professional installation, and adherence to best practices, a metal roofing can provide long-lasting protection and beauty for years to come.

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