Can You Put a Metal Roof Over Shingles?
Quick Summary
We explore the pros and cons of this roofing shortcut — from time and cost savings to serious concerns like trapped moisture, hidden damage, warranty voids, and fire safety violations. We break down when a metal-over-shingle install might work, why many roofers still recommend a full tear-off, and what local codes (including Santa Barbara’s strict fire code) say about it. If you’re considering this approach, read this first.
Introduction
When it’s time to replace your roof, the idea of putting a metal roof over your existing shingles can be pretty tempting. After all, it sounds like a time- and money-saver, right? But the real question isn’t just can you do it — it’s should you? Let’s break down when a roof-over might work, what benefits it offers, and why many professionals still recommend a full tear-off.
The Benefits: Why Some Homeowners Choose a Roof-Over
Installing metal over shingles has its perks, especially if your goal is to save time, money, and avoid a construction mess.
1. Time Savings
One of the biggest advantages is skipping the tear-off. Crews can get straight to work by installing furring strips and laying metal panels, often saving days on the job depending on roof complexity.
2. Cost Savings
No tear-off means no labor costs for removal and no dumpster rental for shingle disposal. Those savings can add up quickly. To see prices for Santa Barbara you can check out Marborg's roll-off containers (Marborg Container). When I called them today (8/6/2025) about a 11-yard roll-off container, they said it's $100 to deliver the roll-off, $210 to haul per load, $4.50/day rental fee, and a likely dump fee (depends on the material) of about $145/ton for C&D (construction and demolition). So yes, the fees can add up in Santa Barbara.
3. Better Insulation
The air space created by furring strips between shingles and metal panels improves energy efficiency by creating natural ventilation. In a study by Oak Ridge National Laboratory, metal roofing systems with above-sheathing ventilation (ASV) reduced heat flow into the attic by as much as 45% compared to asphalt shingle roofs. That kind of performance can translate into lower cooling costs — especially in hot, sunny regions like California. (ORNL Study)
But it’s worth noting that using furring strips does increase the amount of wood and labor needed for the install — which isn’t necessarily the most eco-friendly route. If you want insulation benefits without the extra material, a properly installed metal roof (with reflective coatings and ventilation) directly over a solid deck can still reduce energy consumption. According to the U.S. Department of Energy, cool metal roofing can cut cooling energy use by up to 25% in hot climates compared to dark asphalt shingles. (DOE)
4. Less Disruption at Home
Without the noise and mess of a full tear-off, families can go about their day with fewer interruptions.
The Drawbacks: Why Roofers Often Advise Against Roof-Overs
Despite the upsides, there are some real concerns that make a roof-over less appealing in the long run.
1. You Can’t See What’s Underneath
Without removing the shingles, there’s no way to inspect the roof decking for rot, mold, or other damage. If something’s wrong underneath, it’ll stay hidden — and get worse.
2. Extra Weight
Metal roofs are light, but layering them over shingles adds about 2 pounds per square foot. That might not sound like much, but depending on your roof’s structure, it can put stress on trusses or rafters and lead to sagging or worse. (Metal Roofing Alliance)
3. Future Leaks Are Harder to Diagnose
If there’s a leak, you now have two layers to inspect. Finding the source — and fixing it — gets trickier.
4. Uneven Surfaces and Aesthetics
Old shingles aren’t always flat. Installing furring strips over them can create bumps that affect the look and performance of your metal panels.
5. Warranty Concerns
Roofing warranties may become void if the panels are installed over existing shingles. Taylor Metal, the product we currently use, mentions abrasive surface contact as a reason for voiding a warranty: “Roofing underlayment’s that have granular or abrasive surfaces that can abrade any portion of the Roof System” (Taylor Sample Warranty).
6. Direct-to-Shingle Installation Problems
Installing metal panels directly over shingles might sound like a shortcut, but it can cause serious problems. Asphalt shingles create a rough, uneven surface — think of it like laying metal panels on sandpaper. As the metal expands and contracts with temperature swings, that movement can grind against the gritty shingles underneath, eventually wearing down the underside of the metal and leading to corrosion or even holes.
This type of install also traps heat and moisture between layers. Without ventilation, condensation builds up — increasing the risk of rot, mold, and deterioration of both roofing systems. While furring strips are sometimes used to create an air gap and buffer, adding them also increases the environmental footprint — requiring extra wood, labor, and fasteners. And because many manufacturers prohibit this kind of install, if something goes wrong, you may not be covered under warranty. (Sheffield Metals)
7. Fire Risk: Shingles Under Metal Roofs in Santa Barbara
Here in Santa Barbara, fire safety is a top concern. Asphalt shingles — especially aged or dried-out ones — are considered combustible materials under local fire codes. If you install a metal roof over them, the underlying shingles can still catch fire from embers or heat.
That’s why the Santa Barbara Municipal Code §R905.10.1 prohibits metal roof panels from being installed directly over combustible materials like asphalt shingles or wood shakes. Metal may be fire-resistant, but the layer below still poses a serious risk. The local building code language is clear on this point:
“Deck Requirements" is amended to read as follows: R905.10.1 Deck Requirements. Metal roof panel roof coverings shall be applied to a solid or closely fitted deck, except where the roof covering is specifically designed to be applied to spaced supports. Metal roof panel coverings shall not be installed over combustible shingles or shakes. (ECode)
Local Building Codes: What You Need to Know
Building codes vary, and some cities and states have restrictions on installing metal over shingles. Here are a few examples:
Santa Barbara, CA:
As mentioned, local codes prohibit installing metal roof panels over combustible shingles or shakes. A tear-off is usually required.
Phoenix, AZ:
If the cited local permit exemptions document is current, it seems installing a metal roof over existing shingles may not require a permit — as long as the new roof doesn't compromise the building's fire-resistive rating (TRT-0618 Exemption 17).
Always check with your local building department before moving forward. Permits may be required, and non-compliance could lead to fines, insurance issues, or resale complications.
When Installing Over Shingles Might Be Okay
In the right conditions, installing metal over shingles can still be a viable option. Here’s when it might work:
The existing shingles are in good condition — no warping, curling, or major damage.
There’s only one layer of shingles — many codes don’t allow installation over two or more layers.
Your local building department allows it — always double-check.
Your home’s structure can support the added weight — ideally confirmed by a structural engineer or qualified roofer.
How It’s Done: The Right Way to Install Metal Over Shingles
If you decide to move forward with a roof-over, proper installation is key.
Inspection and measurement: A thorough assessment of your roof is the first step.
Furring strips: These create the necessary space between the shingles and metal for ventilation and insulation.
Proper underlayment: If shingles are left in place, a high-temperature underlayment is essential.
Trimming shingles: Edges at eaves and gables may need to be cut back for a clean, sealed finish.
Panel installation: Panels are secured to the furring strips, and finishing touches like ridge caps and flashing are added.
Ventilation: It’s critical to ensure airflow between the layers to prevent condensation and mold.
And don’t skip the most important step: hire an experienced metal roofing contractor who’s done this kind of job before. Mistakes here can cost thousands later.
So…Should you install metal over shingles?
Here’s the truth: putting a metal roof over shingles can be done, but it isn’t always the best choice. While you might save time and money up front, hidden damage, structural issues, and warranty voids could end up costing more in the long run.
If your roof is in great shape, local codes allow it, and you’re working with a knowledgeable contractor, then yes, it might be a solid option.
But in most cases, a full tear-off is the safer, smarter move. It gives you a chance to start fresh, address any underlying issues, and install your new metal roof the way it was meant to be installed: properly, efficiently, and with full warranty coverage.
Still not sure if a roof-over is right for your home?
Reach out to Legacy Roofing of Santa Barbara — we specialize in metal roofing installations that meet local code and fire safety standards. Whether you’re considering a full tear-off or exploring roof-over options, we’ll help you make an informed decision based on your home’s structure, condition, and location.
Contact us here to schedule a free inspection.
author bio
Jeremy Burrey, owner of Legacy Home Roofing, is a roofing expert with over 20 years of hands-on experience. He specializes in metal roofing, valued for its durability, fire resistance, and long lifespan. A second-generation roofer, Jeremy carries on his family's tradition of quality construction in Santa Barbara and personally oversees each job to ensure top-notch results.
