Can You Install a Metal Roof Over Composite? Pros & Cons

TLDR;

Yes, you can install a metal roof over composite shingles—but it's not always the best solution. It offers cost and time savings, but there are critical structural, ventilation, and warranty considerations to weigh first.

Metal Roofing Over Composite Shingles: What You Need to Know

Yes, it's possible to install a metal roof over composite shingles, and it can even be a smart move in the right conditions. But just because you can, doesn't always mean you should. The decision involves more than slapping one layer over another—there are codes, loads, and long-term impacts to consider.

At The Amish Roofing, we've handled many layered roof installations. We've seen the good, the bad, and everything in between. Let’s walk through the real pros and cons, so you can make the best decision for your home or property.

Understanding Composite Shingles and Metal Roofing

What Are Composite Shingles?

• Made from a blend of materials like asphalt, fiberglass, and recycled plastics
• Lightweight, affordable, and easy to install
• Lifespan ranges from 15 to 30 years depending on quality

What Is Metal Roofing?

• Typically made from steel, aluminum, zinc, or copper
• Highly durable and long-lasting (40–70 years)
• Reflects heat, which helps lower cooling costs
• Available in panels or shingles, with various finishes

Why Layer Metal Over Composite?



• Avoids the hassle of removing the existing roof
• Cuts labor and disposal costs
• Minimizes project time

Installing Metal Over Composite Shingles: Is It Possible?

Yes—but only if your roof qualifies:

• Structural Load: The roof deck must be strong enough to carry the added weight.
• Local Building Codes: Some areas restrict multiple roofing layers.
• Manufacturer Guidelines: Always follow metal roofing manufacturer instructions for overlays.

Key Considerations Before Installing:

• Professional Inspection: Ensure no rot, mold, or major damage beneath shingles.
• Ventilation System: Without proper airflow, moisture can get trapped.
• Flat Surface Prep: Composite shingles must be fairly flat—no major curling or damage.

Benefits of Installing a Metal Roof Over Composite Shingles

Save Time and Labor

• No tear-off required
• Less mess and faster project turnaround

Cost-Effective Roofing Solution

• Reduced disposal fees
• Lower labor costs

Improved Durability and Weather Resistance

• Metal resists wind, hail, and fire better than asphalt
• Can last 2–3 times longer than composite

Better Energy Efficiency

• Reflects solar heat, reducing cooling costs
• Adds a layer of insulation when installed correctly

Enhanced Curb Appeal

• Available in various colors, textures, and styles
• Can mimic tile, slate, or wood shakes

Environmentally Friendly

• Often made from recycled materials
• Fully recyclable at the end of life

Drawbacks of Installing Metal Over Composite

Added Weight on Roof Structure

• Double layers mean more stress on framing
• Older homes may not be built to handle it

Moisture and Ventilation Issues

• Trapped moisture can lead to:
• Mold
• Rot
• Ice dams in cold climates
• Ventilation systems may need to be upgraded

Potential Warranty Voids

• Manufacturer warranties may be void if installed over old shingles
• Insurance claims could be complicated

Higher Initial Cost (Compared to Replacing with Shingles)

• Metal roofing is more expensive upfront than new composite shingles

Noise Considerations

• Rain and hail can be noisier on metal if not insulated properly

Step-by-Step: How to Install a Metal Roof Over Composite Shingles

Step 1: Inspect and Evaluate

• Check structural integrity of the roof deck
• Look for signs of rot, sagging, or water damage

Step 2: Install Underlayment

• Roll out synthetic or foam underlayment over shingles
• Acts as moisture barrier and smooths out uneven areas

Step 3: Add Battens (Optional but Recommended)

• Wood battens can be added for better airflow and leveling

Step 4: Lay and Secure Metal Panels

• Start at the bottom and work upward
• Fasten panels according to manufacturer specs

Step 5: Install Flashing and Trim

• Apply flashing around chimneys, vents, and valleys
• Use sealants to ensure a watertight barrier

Step 6: Final Inspection

• Check for secure fasteners, sealed edges, and aligned panels
• Confirm proper ventilation setup

Risks of Installing a Metal Roof Over an Old Composite Roof

Compromised Ventilation

• Poor airflow can shorten roof lifespan
• Consider adding ridge or soffit vents

Increased Risk of Moisture Accumulation

• Trapped moisture between layers = potential for long-term damage

Insurance and Warranty Limitations

• Talk to your insurance company before proceeding
• Confirm that any new warranties are still valid

Poor Installation Can Lead to Bigger Problems

• Buckling
• Leaks
• Incomplete seals around penetrations



At The Amish Roofing, we always assess whether an overlay is truly safe and worth it for our clients. Cutting corners up front can cost more in the long run.

Should You Install a Metal Roof Over Composite Shingles?

It Depends on Your Situation:

• If your roof is structurally sound and you're looking for long-term value: Yes, it can be a smart investment.
• If your current roof has ventilation or moisture issues: No, it’s better to do a full tear-off.

Questions to Ask Before Deciding:

• How old is your current roof?
• Has it had leaks or water damage?
• Are there any dips or structural concerns?
• Do local codes allow it?

When in doubt, The Amish Roofing recommends getting a professional inspection before moving forward.

Frequently Asked Questions

Making the Right Roofing Decision

Adding a metal roof over composite shingles can be a smart, cost-effective solution—when done right. It’s fast, efficient, and can offer years of worry-free protection. But it’s not one-size-fits-all.

Before you commit, have your current roof professionally inspected. Weigh the long-term value against short-term savings to help determine the right roof for your home. And make sure you partner with an experienced contractor who will do it right the first time.