When your asphalt shingle roof starts showing its age, you might wonder: can you install metal roof over shingles? The short answer is yes—in most cases, metal roofing can be installed directly over existing shingles, saving you time and money while upgrading to a more durable roofing solution. With nearly six decades in business at ADCO Metals, we’ve helped thousands of property owners put a metal roof over shingles, and we’ve compiled some of our best advice below!
Why the Question “Can You Install a Metal Roof Over Shingles?” Matters to Property Owners
Installing metal roofing over existing shingles has become increasingly popular among homeowners and commercial property owners throughout the Gulf South, with metal roofing options favored in this region for their durability, energy efficiency, and long-term savings. This method, known as a roof-over or retrofit installation, offers several benefits while maintaining the structural integrity of your building.
The process involves securing a new metal roof system directly on top of your current shingle roof, creating an extra layer of protection for your property. This approach works particularly well in our Gulf Coast climate, where weather resistance and energy efficiency are top priorities for property owners.
Key Benefits of Installing a Metal Roof Over Shingles
1. Cost Savings on Labor and Disposal
One of the most immediate advantages is avoiding tear-off costs. Removing old shingles requires significant labor and creates disposal expenses that can add thousands to your roofing project. By installing a metal roof atop existing shingles, you reduce project time from weeks to days, minimizing disruption to your daily operations or family life.
2. Enhanced Energy Efficiency
The air gap created between your existing shingles and new metal roof acts as additional insulation. This extra barrier helps regulate indoor temperatures year-round, potentially reducing cooling costs during the peak of summer’s heat. A study conducted by the Oak Ridge National Laboratory (ORNL) found that with proper installation, retrofit roofs are beneficial in reducing heat flux from the exterior to the conditioned interior of the buildings they protect.
Moreover, research conducted by IIBEC suggests that installing a metal roof over existing roofing provides opportunities to add an air cavity between the old roof and the metal, improves ventilation, possibly adds insulation, radiant barriers, and more – all of which can reduce heat gain, essentially reducing cooling loads and costs across the board.
The CERAM-A-STAR® coating system we apply to our Galvalume™ roofs reflects solar heat, further improving your building’s energy performance, and “cool color” technology can maximize your energy savings as well.
3. Superior Weather Protection
Our region faces unique weather challenges, from intense summer heat to hurricane-force winds. Metal roofing installed over shingles creates a double-barrier system that provides exceptional protection against wind-driven rain, a common concern for property owners in the Gulf South region. This dual-layer approach helps prevent water infiltration while maintaining ventilation to prevent moisture buildup.
Important Considerations Before Roof-Over-Shingle Installation
Building Code Requirements
Though local building codes vary, they typically allow one layer of roofing material over existing shingles. However, regulations vary by parish and county. Be certain to consult with contractors who have a deeper understanding of the local building codes in your area. Our experienced team stays current with building codes across our service area, from Baton Rouge to Mobile, ensuring your project meets all local requirements.
Structural Assessment
Before proceeding with installation, a thorough inspection determines whether your roof structure can support the additional weight of a metal layer atop it. While metal roofing is surprisingly lightweight—often weighing less than asphalt shingles—the combined weight must fall within safe limits for your building’s design.
Existing Roof Condition
Can you install metal roof over shingles that are damaged? Not always. Your current roof must be in reasonable condition. Signs that require shingle removal before metal installation include:
- Widespread moss or algae growth indicating larger moisture problems
- Extensive water damage or rot in the roof deck
- Multiple layers of existing roofing materials
- Severe sagging or structural issues
How to Install a Metal Roof Over Existing Shingles
Step 1: Comprehensive Inspection
The critical first step in answering the question, “Can you install a metal roof over shingles?” is to conduct a detailed assessment of your existing roof structure, checking for damaged areas that need repair before installation begins.This inspection includes checking the condition of current shingles, identifying any soft spots or damage in the decking beneath, and verifying that the roof meets requirements for a metal-over-shingle installation.
During this phase, certified installers should take precise measurements of the roof’s dimensions, including all valleys, hips, ridges, and penetrations. This ensures accurate material ordering and minimizes waste. For properties in hurricane-prone areas like southern Louisiana and Mississippi, special attention should be paid to the existing roof’s wind resistance and attachment methods.
Step 2: Surface Preparation
Once the inspection confirms the roof is suitable for overlay installation, and you have gathered the materials you need to install a metal roof, any minor issues discovered during assessment should be addressed. This includes replacing damaged shingles, securing loose materials, and ensuring the surface is clean and stable.
Furring strips or battens should then be installed across the existing roof, typically running perpendicular to the roof slope. These 1×4 or 2×2 wood strips serve multiple purposes: they create essential ventilation channels between the old and new roofing systems, provide a level nailing surface for the metal panels, and help prevent telegraph marks where the metal might otherwise conform to the shingle pattern below. In areas with significant temperature variations, this air gap is crucial for preventing condensation and managing thermal expansion.
Step 3: Underlayment and Moisture Barrier Installation
Before any metal panels are installed, a high-performance synthetic underlayment or specialized roofing felt should be applied over the furring strips. This layer acts as a secondary defense against water infiltration—particularly important given the Gulf Coast region’s heavy rainfall and storm exposure. Quality underlayment should exceed standard requirements, featuring superior tear resistance and UV stability.
Particular attention should be paid to valleys, where additional ice and water shield should be installed for extra protection. Around roof penetrations such as vents, pipes, and chimneys, self-adhering membrane materials should be applied to create a watertight seal. This step is especially critical when installing metal roofing over shingles, as it prevents any moisture that might penetrate the metal from reaching the old roofing material below.
Step 4: Metal Panel Installation
The installation of the metal roofing system should begin from the eave and work upward. Each panel should be positioned with precision, ensuring proper overlap and alignment. For 5V Crimp and corrugated panels, consistent spacing should be maintained using specialized fasteners with rubber washers that compress to create weathertight seals.
Standing seam installations require additional care, as panels are mechanically seamed together using specialized tools that create interlocking joints without exposed fasteners. Only corrosion-resistant fasteners appropriate for coastal environments should be used, typically stainless steel or specially coated screws that match the panel color. Each fastener should be driven to the correct depth—tight enough to compress the washer for a seal, but not so tight that it deforms the metal or compromises the washer’s integrity. Panel overlap specifications vary by product and wind zone requirements, but installations should always exceed minimum standards for high-wind regions.
Step 5: Flashing, Trim & Finishing Touches
The final phase of installing metal roofing over shingles involves installing all the components that ensure the new metal roof performs flawlessly for decades. Ridge caps should be installed along all peaks, with closure strips that prevent wind-driven rain and pest intrusion while maintaining ventilation. Valley flashing directs water flow away from vulnerable joints, while gable trim protects roof edges from wind uplift.
Around chimneys and skylights, custom-fabricated flashing should be installed that integrates seamlessly with both the metal roofing and existing features. Pipe boots should be fitted around plumbing vents, and any necessary ventilation components should be properly integrated.
A thorough final inspection should then be conducted, checking every fastener, seam, and transition point. Any metal shavings from cutting or drilling should be carefully removed to prevent rust stains. The completed installation not only protects the property but also enhances its appearance with clean, straight lines and professional finishing touches.
Can You Install Metal Roof Over Shingles?: Frequently Asked Questions
How long does it take to install metal roofing over shingles?
Most residential roof-over projects are completed within 2-4 days, while larger commercial installations may take 1-2 weeks. This is significantly faster than tear-off and replacement, which can take twice as long.
Will installing metal over shingles void my warranty?
In many cases, with retrofit roofing installed by certified professionals using manufacturer-approved methods, your metal roofing warranty remains fully valid. ADCO Metals provides comprehensive warranties on both materials and workmanship.
Can you retrofit a metal roof atop shingles with existing roof damage?
Minor repairs can often be addressed before installation, but significant damage requires shingle removal. In order to be completely certain that your roof is suitable for metal overlay, you may wish to hire professionals to conduct a thorough inspection of your roof before beginning a retrofit roofing project.
How much weight does metal roofing add over shingles?
Metal roofing typically adds only 1-2 pounds per square foot, well within the load capacity of most structures. Structural capability to handle the extra load will be determined during your initial assessment.
Does metal over shingles require special ventilation?
Yes, proper ventilation prevents moisture buildup between layers, and is known as ASV or above sheathing ventilation. Be sure to install furring strips or specialized systems to ensure adequate airflow throughout your new roof system.
What’s the cost difference between roof-over and complete replacement?
Installing a metal roof over your shingles will save you a significant amount of money compared to complete tear-off and replacement, primarily through reduced labor and disposal costs while delivering increased ROI in the realms of overall performance, reduced cooling costs and longevity.
Why Property Owners Choose ADCO Metals for Roof-Over Projects
When considering the question “Can you install metal roof over shingles?” the answer is a resounding yes—and with significant benefits to follow. Whether you’re protecting valuable equipment, reducing energy costs, or simply upgrading your property’s appearance and value, installing metal roofing over shingles represents a smart investment in your building’s future.
ADCO Metals is proud to be a trusted partner in roof-over and retrofit installations. Our team specializes in both residential and commercial installations, from backyard workshops to agricultural buildings to large commercial facilities. We pride ourselves on quick response times—typically providing estimates within 24-48 hours—and maintaining the prime-quality, American-made materials that ensure your metal roof over shingles is built to last.
We’ll help you evaluate whether a roof-over installation makes sense for your property or if a complete tear-off would better serve your long-term needs. Ready to explore your metal roofing options? Contact ADCO Metals today for a free estimate or call us at (985) 882-3222 or (601) 798-4600 to begin fortifying your build for the future.
