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The Problems of Doing a “Roof Overlay”

Date: February 15, 2024

Are you getting ready to upgrade your home's roof? Perhaps you've come across the concept of "roof overlay" or adding new shingles over the existing ones. It's a choice you might be considering. While it may appear to be a convenient and budget-friendly shortcut at first, there are important factors to weigh in the larger picture.

Exploring the decision between a "roof overlay" and a complete "roof replacement," we unveil crucial insights to guide your choice. This exploration takes you through the nuances of doing a "roof over," shedding light on its potential consequences and unveiling the array of benefits of doing "roof replacement" that might influence your decision. Let's dive into the intricacies of roofing choices, helping you make an informed and intriguing decision for your home's future.

roof overlay

Reasons why you should not do a roof overlay:

Let's check further each of the reasons why roof overlay or adding a layer of shingles over existing old shingles might not be a good idea:

1. Premature Life of New Shingles:

  • When you add a new layer of shingles over old ones, the underlying old shingles may have uneven surfaces, bumps, or damage. This uneven foundation can lead to poor adhesion of the new shingles, affecting their overall performance.
  • The new shingles may not lay flat, and this unevenness can create pockets where water might accumulate. This pooling of water can accelerate the deterioration of the shingles and, in turn, reduce their lifespan.
  • Additionally, the old shingles may have lost some of their flexibility and stability over time. Placing new shingles on top can cause the old ones to transfer their vulnerabilities to the new layer, further shortening their lifespan.

2. Curling and Buckling Issues:

  • The underlying old shingles may already exhibit signs of curling or buckling due to weather exposure, age, or other factors. Placing new shingles on top exacerbates these issues.
  • Curling can occur when the old shingles absorb moisture unevenly, leading to distortions. When new shingles are added, they might not adhere properly to the curled surface, creating gaps and vulnerabilities.
  • Buckling, or the formation of waves in the shingles, can be exacerbated when the new layer doesn't have a smooth foundation. This compromises the structural integrity of the roofing system and can result in premature failure.
shingles curling

3. Voiding Manufacturer Warranties:

  • Many shingle manufacturers explicitly state in their warranty policies that their products should not be installed over existing layers of shingles. If you ignore this guideline, it can void the warranty, leaving you without the protection that the manufacturer would otherwise provide.
  • Manufacturers conduct extensive testing and research to determine the optimal conditions for their products. Deviating from their recommended installation methods, such as adding shingles over old ones, may lead to issues that the warranty would typically cover.
  • Without the manufacturer's warranty, you may be solely responsible for any defects or failures in the roofing system, potentially leading to increased maintenance costs and the need for premature replacements.

Benefits of getting a new roof and not doing a “roof overlay”:

Choosing to opt for a new roof replacement instead of doing a roof overlay can offer several benefits:

1. Enhanced Longevity: A new roof replacement provides an opportunity to start afresh with a clean slate. The installation of new materials ensures optimal performance and longevity without the potential issues associated with aging or damaged existing shingles.

2. Improved Energy Efficiency: New roofing materials often come with advanced technologies and improved insulation options. Upgrading your roof during replacement can enhance energy efficiency, helping to regulate indoor temperatures and potentially reducing heating and cooling costs.

3. Enhanced Curb Appeal: A new roof can significantly enhance the visual appeal of your home. The selection of modern roofing materials, colors, and styles allows you to customize the look of your roof, adding to the overall aesthetic value of your property.

4. Structural Integrity and Safety: Over time, the structural integrity of an existing roof may be compromised due to wear and tear. A new roof replacement ensures that the underlying structure is sound, providing better protection against leaks, water damage, and potential safety hazards.

new roof installation

5. Compliance with Building Codes: Building codes and regulations are updated over time to reflect construction and safety standards advancements. A new roof replacement ensures that your roofing system complies with current building codes, providing peace of mind and avoiding potential legal issues.

6. Reduced Maintenance Costs: While the initial cost of a new roof may be higher than adding another layer, the long-term savings can be significant. A new roof typically requires less maintenance, reducing the need for frequent repairs and replacements compared to an older, layered roof.

7. Increased Home Value: A new roof can add substantial value to your home. Potential buyers often see a well-maintained and aesthetically pleasing roof as a positive feature, making your property more attractive and potentially increasing its resale value.

8. Warranty Coverage: Installing a new roof often comes with warranty coverage from the manufacturer. This warranty provides protection against defects and issues that may arise with the roofing materials, giving you added peace of mind and potentially saving you money on future repairs.

9. Better Weather Resistance: Newer roofing materials are designed to withstand harsh weather conditions more effectively. They offer improved resistance to wind, rain, snow, and other environmental factors, ensuring the longevity and durability of your roofing system.

10. Environmental Considerations: Some modern roofing materials are more environmentally friendly, using recycled or sustainable materials. Choosing eco-friendly options during a roof replacement can contribute to a greener and more sustainable home.

new asphalt shingle roof


While the initial appeal of doing a roof overlay may hint at cost savings, it could potentially direct a host of issues that impact the durability and effectiveness of your roof. Recognizing these potential consequences becomes paramount when navigating decisions regarding roofing maintenance and replacement.

Moreover, seeking guidance from seasoned roofing professionals adds an extra layer of assurance. Their expertise allows for a comprehensive exploration of various options tailored to your specific needs, ensuring both suitability and optimal, long-term results. Consulting with these experts proves invaluable in making well-informed decisions for the enduring well-being of your roofing system.

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