Can You Reroof Over Architectural Shingles?

The decision to reroof over existing architectural shingles presents a unique opportunity to extend the life of your roof while potentially saving time and money. However, several critical factors, including structural integrity, local building codes, and the total weight of the new roof, must be considered. Let's explore these factors and the potential benefits and drawbacks of this approach.

Evaluating the Feasibility of Reroofing

While it is technically possible to add a new layer of shingles over an existing layer, this method should be approached with caution. The first step is to assess the structural integrity and local building codes, which may have specific regulations regarding roof weight limits. Striking a balance between cost savings and safety is crucial.

Structural Integrity and Weight Limits

The structural integrity of your existing roof is paramount. If your current roof is well-preserved, with no significant damage, you may consider reroofing. However, if the existing roof shows signs of wear and tear or if there are concerns about its structural integrity, it may be advisable to completely replace the old roof. Additionally, local building codes and weight limitations should be strictly adhered to.

Challenges of Reroofing

Adding a new layer of shingles over an existing layer of shingles can indeed save you time and money, but it comes with its own set of challenges. For instance, if your current shingles are not flat with no moss, the new layer will take on these imperfections, leading to an uneven and potentially unsightly roof.

Warranty Considerations

It's also important to note that reroofing over existing shingles may void your warranty. Moreover, the asphalt shingles you install on top of the existing ones will not last as long as if you were to install them on a clean, flat surface. The overall lifespan of the new shingles may be reduced by about half due to the additional weight and the uneven surface of the existing layer.

Aesthetic Concerns

Aesthetically, a reroofed roof may not look as neat and uniform as a roof with new and clean shingles. Old shingles can create dips, bumps, and inconsistencies that can be difficult to conceal with a new layer. If you have a warranty, it's always better to tear off the old shingles to ensure that any issues under the old roof are addressed before installing the new ones.

Protection and Mechanical Drawbacks

Another consideration is the additional protection provided by the old roof. If your first roof leaked, a second layer might also leak in the same spot. Additionally, if you have an air conditioning system, the extra weight and heat from the existing shingles could increase your electricity bills.

Pros and Cons of Installing Asphalt Shingles on Top of Existing Asphalt Shingles

While it is technically possible to install new asphalt shingles over existing ones, there are both advantages and disadvantages to this approach:

Pros:

No removal of the old roofing is required, reducing labor and cleanup costs. No risk of leaks from sudden rain as the existing roof serves as a subroof.

Cons:

No assessment of the sheeting underneath the old roof is possible, meaning any underlying damage may go undetected and worsen over time. The flashing around roof protrusions like chimneys and stacks may need adjustment, potentially making the new shingles less efficient. Extra length nails are required, and nail guns have a higher risk of puncturing the new shingles.

Given these considerations, the decision to reroof over existing shingles should not be taken lightly. While it can be a cost-effective solution, it is essential to weigh the pros and cons carefully and consult with a professional to ensure the best outcome for your roofing project.

Professional Guidance and Best Practices

For guidance on roofing options and best practices, explore my dedicated Quora Profile on Home Improvement and Construction. Whether you are looking to extend the life of your current roof or need to perform a complete replacement, professional advice can help you make the right decisions for your specific situation.