Can you put a metal roof over shingles? Yes, but only over a single layer of shingles on a solid, dry deck that lies reasonably flat. Doing it saves roughly $0.70 per square foot compared to a full tear-off. On a home with 2,000 to 3,000 square feet of roof, that’s about $1,400 to $2,100 in savings. If there are two or more layers, soft wood, or active leaks, the old roof should come off.
Can You Put a Metal Roof Over Existing Shingles?
Under the right conditions, metal overtop of shingles is a great option. We install metal over existing shingles in one situation: one layer of asphalt shingles, a deck that passes inspection, and a standing seam metal system going on top.
We never put new shingles over old shingles. Even a single old layer under new shingles usually voids the shingle manufacturer’s warranty, and keeping that warranty requires the full roofing system installed on a clean deck. Metal is the only roof we’ll overlay.
Some building codes allow a re-roof over existing shingles, with strict conditions:
- The existing roof has to be a single layer of shingles.
- The deck has to be solid and dry, with no rot or water damage.
- The new system has to meet the code’s fastening, underlayment and eave ice protection requirements.
If any one of those conditions isn’t met, a tear-off is required. Just because Code allows it doesn’t make it the right call for your house, and we’ll tell you when a tear-off is the better option.
How We Decide: The Deck Inspection
Everything depends on the deck, so we inspect it before we recommend anything. On the roof, we walk every section and feel for soft or spongy spots. We pay extra attention around chimneys, valleys, skylights, pipe boots and the eaves. We also look for:
- sagging between rafters
- nail pops
- shingles that are badly cupped or curled
In the attic, we check those same areas from underneath. We look for:
- daylight showing through the boards
- water stains
- dark or delaminating plywood
- mold
- frost or rust on nail tips
- wet insulation
Some of these problems can’t be seen from the roof, which is why inspecting the attic is crucial..
If we find any issues like a soft or sagging deck, active water damage, mold, or more than one layer already on the roof, it’s an automatic no for putting metal over shingles. If anything points to a deck problem, we recommend a tear-off, even though it costs more for the project, it’s better in the long run.
How Many Layers Is Too Many?
For metal, we’ll go over one layer. At two layers, we want a tear-off so we can properly inspect the decking and give the new roof a uniform surface. No manufacturer will uphold a warranty on a roof installed over multiple layers. If something goes wrong, the homeowner pays out of pocket, so we don’t recommend it.
What Goes Between the Shingles and the Metal
We install a synthetic breathable underlayment directly over the shingles. Breathable matters because any moisture left in the old shingles or deck needs a way out. A non-breathable layer can trap it, and that leads to condensation and rot you can’t see. The underlayment also keeps the metal panels from rubbing against shingle granules as the panels expand and contract.
Our fastening tools and process is different when we install a metal roof on top of shingles. With a mechanically locked standing seam system, the clips go through the old shingles into the deck, so we use longer screws to get full penetration into solid wood. Shingles compress, so we’re careful not to overdrive, and each clip has to sit flat and square. We follow the manufacturer’s clip spacing and tighten it up near the eaves, rakes and ridges, where wind uplift is highest.
What Changes With Ventilation, Flashing and Edges
Going over shingles changes the ventilation of your home, the flashing and edging for your roof.
Ventilation. We cut the ridge slot through the old shingle layer and install a vented ridge cap with closures. The closures let air out but keep wind-driven rain, snow and bugs from getting in. Old box vents and turbines come out, and the openings are decked over before the underlayment goes down. We also check that the soffits have enough intake to balance the ridge. Ventilation only works when air can enter at the bottom and leave at the top.
Flashing. Nothing old gets reused. Standing seam has its own trim system, so:
- Walls get new sidewall and endwall flashing, with closures sealed to the panels.
- Chimneys and skylights get new metal flashing sized for the added roof height.
- Wider chimneys get a cricket behind them to divert water.
- Pipe vents get new boots made for metal roofing, placed in the flat of the panel rather than across a seam.
Edges. The old layer adds thickness, so the eave and rake trim is sized to cover it cleanly. At the eaves, the panels hem over a cleat so they lock down against wind. At the rakes, the trim fastens into a cleat as well, so no exposed screws are needed. The water moves quicker on a metal roof, so we would recommend a 6 inch gutter if you don’t have one already.
Metal Overlay vs. Tear-Off at a Glance
| Metal over one layer of shingles | Full tear-off | |
| Existing layers | One only | Two or more, or any doubt about the deck |
| Deck condition | Solid, dry, reasonably flat | Soft, sagging, wet, moldy or rotted |
| Upfront cost | About $0.70/sq ft less | Higher: labor to strip the roof, dumpster, disposal |
| Start of job | Installation begins day one | Tear-off and cleanup come first |
| Deck inspection | Attic and roof walk, plus any spots found during install | Full view of the bare deck |
| Next replacement | Two layers to remove later | One layer to remove |
The savings are real, but when this roof eventually needs replacing, there will be two layers to remove, so some of the cost shows up down the road. For a full look at pricing, see our metal roof cost guide for West Virginia.
Where the Savings Come From
The $0.70 per square foot comes from three things you skip: the labor to strip the old roof, the dumpster rental, and the disposal fees for hauling shingles away. The crew also starts installing the new roof on day one instead of spending the first part of the job on tear-off and cleanup.
The savings don’t come from cutting corners on the roof itself. All the accessories are new, including the vented ridge, flashing, and eave and rake trim. If you’re weighing whether to replace at all, our roof replacement services page covers the options.
What If You’re Covering Up Rot?
This is the worry we hear most. The answer is the inspection above.
If we find a bad spot during the install, we stop work in that area, take photos, and show you right away, in person or by text. We explain what we found and what it takes to fix it. Once you approve, we cut out the bad wood, install new decking, and keep going, usually the same day.
Replacement is billed at the per-sheet price listed in your contract, so there are no surprises. We typically charge $85 a sheet to remove rotten wood and replace it with new plywood or OSB. For more on how a replacement runs from start to finish, read our guide to what to expect during a roof replacement.
Insulation and Noise
The old shingle layer adds little insulation, not enough to change your energy bill in a noticeable way. Don’t count on it for savings.
Noise is different. Between the shingles, the underlayment and your attic insulation, rain on a metal roof installed over shingles is quieter than most people expect.
A Recent Overlay Job: Masontown, WV
This September, we installed a standing seam metal roof over existing shingles on a home in Masontown. The attic inspection showed sound decking, with no rot, water damage or soft spots, so the house was a good fit for an overlay.
We laid synthetic breathable underlayment directly over the shingles and fastened the standing seam panels on top. All the accessories were new: vented ridge, flashing, and eave and rake trim. The homeowner got a full metal roof without the cost and mess of a tear-off.
FAQ
Will the old shingles show through the metal?
They can if the surface underneath is uneven. Flat metal panels can show bumps, buckles or curled shingles beneath them. That’s one reason a lot of curling or buckling pushes a job toward a tear-off.
Does the extra layer add weight to the roof?
An overlay adds to what’s already on the deck. If you have any doubt about your framing, ask your contractor to check it before you commit.
What if I get a tear-off recommendation and want a second opinion?
Get one. Ask the second contractor to show you the attic findings and the soft spots they found, not just a verdict. A tear-off recommendation should come with photos and specifics.
Talk to Us Before You Decide
If you’re thinking about a metal roof over your existing shingles, call Eclipse Construction at (304) 244-3334 or request a quote. We serve homeowners in Morgantown, Cheat Lake, Bridgeport, Clarksburg, Fairmont, Westover and Star City, and we’ll tell you whether your roof is a fit for an overlay or needs a tear-off.
