Metal Roof Over Shingles Problems | Unveiling the Potential Challenges

When it comes to roofing options, metal roofs have gained immense popularity due to their durability, longevity, and energy efficiency. One practice that has garnered attention is installing a metal roof over existing shingles. While this may seem like a convenient solution, there are potential problems that homeowners and contractors should be aware of before embarking on such a project. In this article, we will explore the benefits and challenges of installing a metal roof over shingles, shedding light on the potential problems that can arise.

The Benefits of Installing a Metal Roof Over Shingles

Installing a metal roof over existing shingles offers several advantages, making it an enticing option for homeowners:

  • Cost Savings: One of the primary benefits is cost savings. Installing a new metal roof over shingles eliminates the need for tearing off the existing roof, saving on labor, disposal fees, and time.


  • Reduced Environmental Impact: By avoiding the removal of old shingles, the environmental impact of disposing of roofing materials is minimized.


  • Improved Insulation: The existing shingles can act as an additional layer of insulation, enhancing energy efficiency and potentially reducing heating and cooling costs.

Potential Problems and Challenges

Despite the benefits, there are notable problems that can arise when installing a metal roof over shingles:

  • Weight Issues: Adding another layer of roofing material increases the weight on the structure. It’s crucial to ensure that the building’s structure can support the combined weight of both the metal roof and the existing shingles.


  • Uneven Surface: Shingles can degrade over time, leading to an uneven surface. Installing a metal roof over such an uneven base can result in an uneven appearance and potential water pooling.


  • Moisture Trapped: Moisture can get trapped between the old shingles and the new metal roof. This trapped moisture can lead to rot, mold growth, and eventually compromise the structural integrity.


  • Voided Warranties: Manufacturers’ warranties for metal roofing products might be voided if installed over shingles, as the shingles’ condition can impact the performance of the metal roof.

Proper Preparation and Installation

To mitigate potential problems, proper preparation and installation are essential:

  • Inspection: Thoroughly inspect the existing shingles for signs of damage, decay, or unevenness. Replace or repair any compromised areas before proceeding.


  • Ventilation: Proper ventilation is crucial to prevent moisture buildup. Ensure that the attic and roof space have adequate ventilation to reduce the risk of moisture-related issues.


  • Underlayment: Use an appropriate underlayment between the shingles and the metal roof to create a moisture barrier and minimize unevenness.


  • Consult Professionals: It’s recommended to consult with roofing professionals who have experience in metal roof installations. They can assess the feasibility of the project based on the specific conditions of your roof.


Installing a metal roof over shingles can be a viable option under the right circumstances. However, it’s essential to weigh the benefits against the potential problems and challenges that can arise. Proper preparation, careful inspection, and consultation with experts are crucial steps to ensure a successful installation that provides the longevity and performance expected from a metal roof. Before embarking on this project, homeowners should thoroughly research, consider their specific situation, and make an informed decision to safeguard their investment and the integrity of their home.