Top 5 Pros and Cons of Installing a Metal Roof Over an Asphalt Roof
If you’re considering upgrading your roof, you may have come across the option to install a metal roof over your existing asphalt shingles. This method can save time and money, but it also comes with its own set of advantages and drawbacks.
Metal roofs are known for their durability, energy efficiency, and long lifespan, while asphalt shingles remain a popular, cost-effective choice. But is installing a metal roof over asphalt the right decision for your home?
Rescue My Roof has been a leader in the roofing industry for over a decade, helping homeowners make informed decisions about their homes.
In this article, we’ll explore the pros and cons of installing a metal roof over an existing asphalt roof, helping you weigh the benefits and potential downsides. Ultimately, you’ll know if installing a metal roof is best for you.
Top 5 Pros of Installing a Metal Roof Over Asphalt
Metal roofs have a myriad of advantages, including:
1. Cost Savings
One of the main benefits of installing a metal roof over an asphalt roof is cost savings. By leaving the existing shingles in place, you avoid the labor costs of tearing off the old roof, hauling away debris, and disposing of the materials.
Additionally, leaving the asphalt shingles can act as an extra layer of insulation, potentially lowering energy costs.
2. Reduced Installation Time
Installing a new metal roof over an existing asphalt roof can significantly reduce the time it takes to complete the project. Since there is no need to remove the old shingles, the roofers can get right to work installing the metal panels, making the entire process faster and less disruptive to your home life.
3. Extra Layer of Protection
Leaving the asphalt shingles in place creates an additional layer of protection between your home and the elements. The metal roof will act as the primary defense against rain, snow, wind, and UV rays, while the underlying asphalt shingles provide a secondary shield, further safeguarding your home from potential leaks and weather damage.
4. Energy Efficiency
Metal roofs are highly energy-efficient, as they reflect sunlight and help regulate the temperature inside your home. By installing a metal roof over asphalt, you combine the insulating properties of the asphalt shingles with the reflective benefits of metal. This can result in lower cooling costs during hot summer months.
5. Longevity
Metal roofs can last 40 to 50 years, much longer than the 15 to 30-year lifespan of asphalt shingles. Installing a metal roof over your existing asphalt roof means you won’t have to worry about replacing your roof for decades to come.
Additionally, metal is highly resistant to weather damage, pests, and fire, making it a durable and low-maintenance option.
5 Cons of Installing a Metal Roof Over Asphalt
Owning a metal roof isn’t all rainbows and sunshine. Here are five things you need to be prepared for:
1. Increased Weight
While metal roofing is relatively lightweight compared to other materials like tile or slate, adding a new roof on top of an existing one will still increase the overall weight on your home’s structure.
If your home’s framing or foundation isn’t strong enough to support the additional weight, it could lead to structural issues down the line. A professional roofing contractor should inspect your home to ensure that it can handle the extra load.
2. Moisture and Ventilation Issues
Installing a metal roof over asphalt shingles can trap moisture between the layers, especially if the existing roof has water damage or poor ventilation. This trapped moisture can lead to mold, mildew, and rot, which can compromise the integrity of your roof over time.
Proper ventilation is essential to prevent these issues, so be sure to consult with a roofing professional to assess whether your home has adequate airflow.
3. Potential for Hidden Damage
If the underlying asphalt roof is damaged, installing a metal roof over it could mask problems such as leaks, water damage, or rotting wood. These issues could worsen over time if they aren’t addressed before the new roof is installed. It’s crucial to thoroughly inspect the existing roof for any signs of damage before deciding to overlay it with metal.
4. Aesthetics and Height
Adding a metal roof over asphalt shingles will increase the height of your roof, which could alter the appearance of your home. This additional layer may also create a bulky or uneven look, particularly around edges, eaves, and valleys. While this might not bother some homeowners, others may find the change in appearance less appealing.
5. Code and Warranty Considerations
Before installing a metal roof over an asphalt roof, it’s important to check local building codes. In some areas, it may not be permissible to have more than two layers of roofing materials, so installing a metal roof over asphalt could violate building regulations.
Additionally, the warranty on the metal roof may be voided if it’s installed over an existing roof, so make sure to read the warranty terms carefully.
When Installing a Metal Roof Over Asphalt Is a Good Option
Installing a metal roof over an asphalt roof can be a good option if:
- Your existing roof is in relatively good condition, with no significant water damage or structural issues.
- You want to save on the cost of tearing off the old roof and reducing installation time.
- Your home’s structure is strong enough to support the additional weight of both roofing systems.
- You live in an area with hot summers, where the energy-efficient benefits of a metal roof can help reduce cooling costs.
When to Consider a Full Roof Replacement
A full roof replacement, including the removal of the existing asphalt roof, may be necessary if:
- Your asphalt shingles are damaged, curling, or buckling, as this could indicate underlying problems that need to be addressed.
- There are ventilation or moisture issues in your attic, which could worsen if left unchecked.
- You’re concerned about the appearance of adding a second layer of roofing.
- Local building codes don’t allow for more than one layer of roofing material.
Is Installing a Metal Roof Over Asphalt Right for You?
Installing a metal roof over an asphalt roof offers several advantages, including cost savings, faster installation, and increased energy efficiency. However, it’s not a one-size-fits-all solution. It’s important to carefully weigh the pros and cons and consult with a roofing professional to assess your home’s structure and current roofing condition. If done properly, installing a metal roof over asphalt can give you a long-lasting, durable roofing solution that offers excellent protection and energy savings.
Ultimately, the decision comes down to the condition of your existing roof, local building codes, and your aesthetic preferences. If your asphalt roof is in good shape and you’re looking for an affordable way to upgrade to metal, this option could be a perfect fit.
However, if there are any underlying issues with your asphalt shingles, a complete roof replacement may be the safer and more effective route.
Learn more with “The Top 8 Problems with Metal Roofs” and “Metal Roof Pricing (6 Types of Metal Roofs).”
Are you considering a roof replacement in southeastern Wisconsin? While Rescue My Roof does not provide metal roofing services, we can help with all of your asphalt and flat roofing needs. Contact us today to get a FREE estimate.
