Yes, you can install a metal roof over shingles if the structure is sound and local codes allow no more than two layers. Key steps include inspecting for damage, adding underlayment, and ensuring ventilation. Benefits include lower costs, faster installation, and a 40–70 year lifespan.
Can you put a metal roof over shingles?
Yes, in most cases, you can install metal roofing directly over existing asphalt shingles, as long as local building codes and the condition of your roof allow it. Metal panels are lightweight typically 100 to 150 pounds per 100 square feet, compared to asphalt shingles, which can weigh up to 400 pounds. Most homes can support this added weight if the existing structure is sound.
However, building codes typically allow a maximum of two roofing layers. If your roof already has two layers, you’ll need to remove one before installing the metal roof. Before beginning, have a licensed roofer assess your shingles and decking for any signs of rot, sagging, or trapped moisture.
Installing metal over shingles can also create ventilation challenges. Without added airflow systems like Above Sheathing Ventilation (ASV), heat and condensation may accumulate, especially in warm or humid regions. Smooth surfaces are also key curled or broken shingles should be leveled before installing metal to avoid “telegraphing,” which makes panel ridges visible.
A professional roof installation inspection can confirm if your home qualifies for this method.
Benefits of installing metal roofing over shingles
Installing metal roofing over shingles offers cost, efficiency, and longevity advantages.
1. Reduced labor and disposal costs
Avoiding tear-off can save $1,000 to $3,000 in labor and landfill disposal fees. This makes the project faster and less disruptive.
2. Longevity and durability
Metal roofing systems last 40 to 70 years, much longer than the 15–30 years typical for asphalt shingles.
3. Energy efficiency
Metal reflects heat and, when paired with ASV, can reduce attic temperatures and cooling demand by 20% to 30%.
4. Sustainability
Metal roofs contain up to 95% recycled materials and are fully recyclable at end of life.
5. Quick installation
Skipping tear-off cuts several days from the installation timeline and allows roofers to work around bad weather windows.
For long-term value and performance, metal roofs are one of the most efficient upgrades you can make.
Step-by-step guide: How to install metal roofing over shingles
1. Inspect roof and shingles for structural integrity
Before installation, inspect for moisture, rot, sagging decking, or curling shingles. If damage is present, it may need to be repaired or removed.
Schedule a roof inspection before moving forward.
2. Choose the installation method
Three main methods include:
- Furring strips (purlins): These elevate the panels, allowing airflow beneath and improving insulation.
- Direct-to-deck attachment: Faster and cheaper, but requires an ultra-flat surface and quality underlayment.
- Shingle recover systems (e.g., 138T panels): These integrate clips and ventilation gaps for premium performance.
3. Add protective underlayment layer
An underlayment such as synthetic sheeting or foil-faced barriers protects metal from shingle abrasion and moisture.
4. Install panels with proper fasteners
Align panels precisely. Use corrosion-resistant screws and manufacturer-recommended clips. Finish with sealed trim and ridge caps. For homes with previous asphalt work, this process may resemble asphalt shingle roof installation.
Common mistakes to avoid
1. Skipping underlayment
This leads to panel abrasion, leaks, and condensation issues. Always use a barrier layer.
2. Overloading the roof
Although metal is light, stacked layers may exceed code or strain older structures.
3. Using the wrong fasteners
Incorrect hardware or installation voids warranties and leads to roof failure.
4. Ignoring ventilation
Without ASV or furring strips, trapped moisture can rot decking or raise attic temps.
Is installing metal roofing over shingles right for your home?
Evaluate slope and support
Roof pitch should be at least 3:12, and the frame must support added material. Homes with existing sagging or layered shingles may not qualify.
Climate matters
In cold regions with heavy snowfall, avoid excess weight. In hot areas, prioritize systems with airflow to reduce attic temps.
Long-term value
Metal roofs have a return on investment (ROI) of up to 85% in many markets. They enhance curb appeal, especially with high-end finishes or standing seam styles.
Homes already using residential roofing materials may transition easily if the structure is sound.
FAQs
Can you paint roof shingles before installing metal?
No. Painting offers no benefit and may off-gas or peel under the metal layer.
Is installing metal over shingles legal in all states?
Yes, where local codes permit it. Most allow up to two roofing layers. Always check local rules first.
What is TPO roofing and how does it compare?
TPO (Thermoplastic Polyolefin) is a membrane roofing used on flat commercial buildings. It lasts 15–30 years, while metal lasts 40–70 years and performs better in extreme weather.
Can I add an A/C unit or solar panels later?
Yes. Standing seam metal roofs are solar-ready. For heavier loads like A/C units, structural framing may be required.
