Installing a metal roof over existing shingles is a smart, cost-effective solution for homeowners and businesses looking to upgrade their roofing without the hassle and expense of tearing off the old one. This method not only saves time and reduces waste but also adds an extra layer of protection and insulation to your property. With benefits like enhanced durability, energy efficiency, and a cleaner installation process, it’s no wonder metal roofing is gaining popularity. In this guide, you’ll discover the key advantages, potential drawbacks, types of metal roofs to consider, and essential steps to ensure a successful installation.
Benefits of Installing a Metal Roof Over Shingles
1. Cost Savings
Installing a metal roof over existing shingles can save you significant money compared to new asphalt shingles. You avoid the expensive process of removing the old roof, which means lower labor costs and no additional screws for metal roofing fees. While the upfront price of metal roofing may be higher, it’s more cost-effective in the long run due to its longevity and energy efficiency.
2. Enhanced Durability
One of the standout benefits of metal roofs is their durability. Unlike asphalt shingles, which need to be replaced every 20 years or so, a metal roof can last decades—often over 50 years or even 60 years. Metal roofs are highly resistant to fire damage, rotting, and damage from termites and insects, making them a robust option for long-term protection.
3. Protection Against the Elements
By installing metal roofing over shingles, you add an extra layer of protection. This helps guard against the elements—whether it’s heavy rain, hail, or intense sun. Metal roofs are also excellent at snow slide-off due to their smooth surface, preventing the accumulation of heavy snow and ice.
4. Better Energy Efficiency
Metal roofs are known for their energy efficiency. They reflect heat rather than absorb it, which helps keep the interior of your home cooler in the summer and warmer in the winter. This can lead to lower energy bills over time, making it a great long-term investment.
5. Less Mess, Faster Installation
Installing metal roofing over shingles is quicker and less messy than traditional roof replacement. You don’t need to tear off the old shingles, which means fewer materials to dispose of and a cleaner, faster installation process. This minimizes disruption to your daily life and keeps your property free from the chaos of a busy construction zone.
6. Sound Absorption
Another unique advantage of adding a metal roof over shingles is sound absorption. The additional layer helps reduce the reverberation of sounds like rain or hail, making your home quieter during storms. This adds to the overall comfort of your living space.
7. Increased Home Value
Because metal roofs have a longer lifespan and superior performance compared to asphalt shingles, installing one can increase your home’s value. Potential buyers are likely to see the long-term durability and low maintenance as attractive qualities, potentially giving your home a competitive edge in the real estate market.
Drawbacks of Installing a Metal Roof Over Shingles
1. Building Code Restrictions
Before you proceed with installing a metal roof over asphalt shingles, it’s crucial to check local codes. In some areas, building codes may not permit this type of installation. If the code requires it, you might need to remove the old roof entirely before placing the new one, which can add to the overall cost and complexity.
2. Weather and Hail Damage
While metal roofs are generally more durable than asphalt roofs, they are still susceptible to extreme weather conditions. Hailstones, particularly larger ones, can cause dents in the metal—especially if the roofing material is made from softer metals like aluminum or copper. This could lead to costly repairs, and it’s important to consider this when selecting your material.
3. Insurance Considerations
In regions where hail is common, make sure that your homeowner’s insurance policy covers damage caused by storms, including hail damage to your metal roof. The storm damage might not be covered under some policies unless specified, so it’s worth reviewing your coverage to avoid unexpected expenses.
4. Professional Installation Required
Installing a metal roof over asphalt shingles requires a specific skill set. This isn’t a DIY job, and it’s best left to experienced contractors or a roofing company with the proper expertise. Professional installation ensures that the roof is correctly applied and avoids issues that could arise from an improper installation.
What Kind of Metal Roof Can Be Used?
Aluminum Roofing
- Highly resistant to saltwater corrosion.
- Perfect for coastal areas with exposure to salty air.
- Lightweight and durable.
Steel Roofing
- Known for its strength and long-lasting durability.
- Available in Galvalume and galvanized versions for added protection against weathering and corrosion.
- Can handle extreme weather conditions without damage.
Copper Roofing
- Offers a classic, high-end look that ages beautifully.
- Soft yet durable, especially in moderate climates.
- Develops a weathering patina over time, which enhances its appearance.
Zinc Roofing
- Quiet and soft compared to other metals.
- Naturally resistant to corrosion, making it a great choice for humid climates.
- Requires minimal maintenance.
Zinc vs Aluminum vs Steel
- Zinc: Offers superior weathering and natural protection.
- Aluminum: Best for resistance to salty air and corrosion.
- Steel: Offers a wider range of variations in design and durability.
Preparing/Inspecting the Existing Roof
Inspecting the Decking
- Ensure the decking, such as plywood, is in good condition. Check for any rotten boards or areas with compromised integrity. Damaged decking could lead to severe structural damage once the metal roof is installed.
Checking for Vulnerabilities
- Look for any vulnerabilities in the roof system. If the decking is compromised, it may affect the overall performance of your metal roof. Consider the weight of the new roof and how it will interact with your asphalt roof.
Reviewing Roof Materials
- Inspect the materials under the shingles. If your roof system includes older or deteriorating materials, they should be replaced before proceeding. Missing or damaged components could lead to leaks or water damage.
Understanding the Importance of Underlayment
- Check the condition of the underlayment beneath the shingles. This serves as the last line of defense against moisture and plays a critical role in keeping the decking dry. Ensure the underlayment is compatible with metal roofing materials.
Evaluating for Future Leaks
- Consider potential leaks from two layers of roofing (the old shingles and new metal). Water may find its way under the metal panels, leading to potential issues that might require metal roof repair. This can result in costly and labor-intensive repairs down the road.
The Cost of Repairs
- Starting from scratch with a new roof system may seem like a larger upfront investment, but it’s often more cost-effective in the long run. If you skip over the tear-off process, you risk missing components or structural problems that could lead to future, expensive repairs.
Steps to Installing a Metal Roof Over Shingles
Install Synthetic Underlayment
- Apply synthetic underlayment over the existing shingles for extra protection. The underlayment should be tear-resistant and provide thermal protection, preventing damage from water or extreme temperatures.
Install Corrugated Metal Panels
- Install corrugated metal panels over the underlayment. These panels are lightweight and durable, providing protection from the elements and enhancing the energy efficiency of your home.
Ensure Proper Venting
- Make sure there is proper venting to allow air flow. This will help with the venting process and prevent trapped moisture, which could damage the roof system.
Secure the Metal Panels
- Once the panels and other essential parts of the metal roof are aligned, securely fasten them to the roof deck. Check for any gaps that could cause water leaks or damage. Ensure the reflective surface of the panels is properly installed to reflect heat and increase energy efficiency.
Final Inspections
- Inspect the final setup for any issues like improper alignment or areas that may need additional protection. Make sure everything is securely fastened to avoid future costly repairs.
Installing a metal roof over shingles can be a cost-effective way to upgrade your home’s roofing system, but it requires careful consideration. While it may save time and money, it’s essential to ensure that your shingles and roof deck are in good condition and capable of supporting the extra weight. Don’t overlook the importance of using a high-quality synthetic underlayment and ensuring proper venting and airflow to maintain the longevity and energy efficiency of your new metal roof. While this method can be effective, it’s always best to consult with a professional if you’re unsure about the structural integrity of your roof. Taking the right steps will help prevent future damage, costly repairs, and ensure that your new roof performs at its best for years to come.