a roof with two layers of shingles
a roof with two layers of shingles

Layering Shingles Over an Existing Roof: Pros, Cons, and What You Need to Know

A roof is a significant investment for most homeowners, and saving money is generally of interest. However, there are some cost-cutting measures that might lessen the upfront investment but lead to higher maintenance costs or a shortened roof lifespan. 

Homeowners often ask their roofing company if they can save money by layering shingles on top of the old shingles (as opposed to removing the old shingles first). This means less labor charges and minimizes disposal costs, but is it worth it?

Understanding Shingle Roofs

Asphalt shingle roofs are one of the most popular roofing choices in the United States, valued for their durability, affordability, and ease of installation. Shingles are typically made from asphalt, a material that provides excellent weather resistance and is available in a variety of colors and styles to suit different home designs.

The construction of a shingle roof begins with a roof deck, usually made of plywood or oriented strand board (OSB). This serves as the foundation for the roofing system. A layer of underlayment, often made from felt or synthetic material, is installed over the deck to provide an additional barrier against moisture.

The shingles are then laid in overlapping rows, starting from the bottom edge of the roof and working upwards. This overlap ensures that water flows off the roof without seeping underneath the shingles. Each shingle is secured with nails and adhesive strips designed to withstand various weather conditions.

Proper installation is critical to the performance of a shingle roof. This includes maintaining correct alignment, using the appropriate number of nails per shingle, and ensuring adequate ventilation beneath the roof. When done correctly, a shingle roof can last 20 to 30 years or more, depending on the quality of the materials and the local climate.

Layering shingles involves installing new shingles directly on top of an existing roof, rather than removing the old ones. Homeowners may opt for this method when they want to avoid the labor-intensive and costly process of tearing off old shingles, which also requires managing waste disposal.

This practice is common when a roof is nearing the end of its lifespan but is not severely damaged. However, there are critical factors to consider, including the roof’s structural integrity and local building codes.

Pros and Cons of Multiple Layers of Shingles

Layering Shingles Over an Existing Roof

There are both advantages and disadvantages to re-roofing by installing new shingles over old ones.

Pros

Cost Savings

Layering shingles eliminates the need for tear-off labor and disposal costs, significantly reducing the overall expense of re-roofing. This can make it an attractive option for budget-conscious homeowners.

Quick Installation

Adding a second layer is faster because it skips the step of removing old shingles. Contractors can complete the job more quickly, minimizing disruption to the homeowner’s routine.

Environmental Considerations

Layering shingles can reduce the environmental impact by minimizing the waste sent to landfills. Instead of disposing of old shingles, the existing layer remains in place, decreasing the amount of roofing material discarded during re-roofing projects.

Temporary Solution

For homeowners who need an immediate fix but cannot afford a full roof replacement, layering shingles over a portion of the roof can provide a temporary solution until a complete re-roofing project becomes feasible.

Cons

Increased Weight

Each layer of shingles adds considerable weight to the roof. For older homes or those with weakened structural integrity, this additional weight can lead to sagging or even structural failure. Florida homeowners, in particular, should be cautious, as the added weight could make their roofs more vulnerable during hurricane season.

Shorter Roof Lifespan

Layering shingles can trap heat and moisture, which accelerates the deterioration of the roofing materials. This reduces the lifespan of the new shingles, meaning homeowners might need another replacement sooner than expected.

Complicated Repairs

Diagnosing and fixing leaks or other issues becomes more challenging when multiple layers are present. Contractors must navigate through layers to find the source of a problem, increasing repair costs and time.

Building Code Restrictions

Some local building codes limit the number of shingle layers allowed. In Florida, for example, building codes often restrict roofs to two layers due to safety concerns. Exceeding this limit can result in fines or the need for immediate roof removal.

Homeowners Insurance

Another consideration when deciding whether to layer shingles is homeowners insurance. Some policies may not cover roofs with multiple layers of shingles due to the increased risks associated with weight and potential moisture damage. Additionally, if a roof with multiple layers sustains damage, insurers might deny claims, arguing that the layered construction contributed to the failure. Homeowners should carefully review their policy or consult their insurance provider before opting for this approach to ensure coverage is not compromised.

Materials Warranties

Some manufacturers of shingles might not honor their warranties if shingles are layered over old ones. Homeowners should verify warranty conditions with the manufacturer before proceeding with a layered installation to avoid voiding their warranty.

Can I DIY Shingling Over My Old Roof?

sideways man working roof with drill

While some homeowners might consider shingling over an old roof as a DIY project, it’s highly recommended to hire a professional. Roofing over an existing layer requires precision to ensure proper alignment, adequate ventilation, and compliance with building codes. 

Professionals have the expertise to identify any underlying issues, such as rot or structural weaknesses, which could be exacerbated by additional weight. Mistakes in installation can lead to costly repairs and void warranties, making professional assistance a valuable investment.

Laying Shingles Over Other Roofing Types

While layering shingles is typically done on asphalt shingle roofs, it is not suitable for all roofing materials.

For instance, layering shingles over metal or wood shake roofs is generally not recommended due to compatibility issues. Additionally, uneven surfaces from existing roofing materials can cause the new shingles to wear out prematurely.

Homeowners should consult a professional roofing company to evaluate whether their existing roof type can support a new layer of shingles. This step ensures that the installation adheres to safety standards and maximizes the new layer’s durability.

Upfront Savings Versus Long-Term Costs

When considering whether to layer shingles, homeowners must weigh the immediate cost savings against potential long-term drawbacks. While layering shingles can be a quick and budget-friendly solution, it may lead to complications such as shorter roof lifespan, structural strain, and higher future repair costs.

Your Lakeland Roofers

Stronghold Roofing & Solar is the choice for all your residential and commercial needs in and around Lakeland. We offer a full range of roofing services, from installation to inspections and repairs, and we are proud to offer customers a free roof estimate that details exactly what to expect for any work we do.

Call today to find out how we can help you become another satisfied customer of Stronghold Roofing!

FAQs – Layering Shingles Over an Existing Roof

Is layering shingles allowed in Florida?

Layering shingles may be permissible in some places, but most areas in Florida limit the roof to a maximum of two layers due to safety and structural concerns.

What are the risks of adding a second layer of shingles?

The primary risks include added weight, reduced roof lifespan, and challenges with future repairs or replacements.

How do I know if my roof can handle another layer of shingles?

A professional roofing contractor can inspect your roof’s structural integrity to determine if it can support an additional layer safely.

Does adding shingles over old ones affect ventilation?

Layering shingles may impede proper ventilation, leading to heat buildup and moisture retention, which can cause damage over time.

What happens if building codes are violated by adding another layer of shingles?

Violating building codes can result in fines, voided insurance coverage, or forced removal of the additional layer. It is essential to consult with local authorities or a professional roofing contractor to ensure compliance.

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