Can You Put a Metal Roof Over Shingles? (Ohio Code)

Can You Put a Metal Roof Over Shingles?

Sometimes. A metal roof can legally go over one layer of dry, sound asphalt shingles if the metal manufacturer allows it, but the Residential Code of Ohio does not allow a new roof over roofing that is water-soaked or deteriorated, and the model code it follows rules out a recover once a roof already has two or more layers. Brothers Metal Roofing normally tears off to the decking on standing seam jobs, because the only way to know the deck is sound is to see it.

By Isaac Smith, Brothers Metal Roofing · Updated November 2026

What the Ohio building code says

Ohio homes are built and re-roofed under the Residential Code of Ohio, which is based on the International Residential Code. Section 908.3.1.1 lists the conditions where a roof recover (installing new roofing over the old) is not allowed. The City of Kettering’s reroofing guide quotes it directly: a recover is not permitted “where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing.” The model code also bars a recover where the roof already has two or more layers of any roof covering.

So the legal answer depends on what is up there now. One dry layer of shingles on a solid deck: possibly yes. Two layers, wet shingles or a soft deck: no, it all has to come off. Your city or county building department has the final word, and some add their own rules.

Why we tear off to the deck anyway

Going over shingles saves the cost of tear-off and disposal, and it is faster. The problem is what you cannot see. On a Centerville, Ohio ranch, the shingles looked ordinary from the ground. Once they came off, a large section of rotten decking showed up on the back slope. A roof laid over the top would have sealed that rot in under a 40-year roof.

Hidden rot keeps spreading. We never install over rotten or damaged decking; bad boards are cut out and replaced with new OSB first.
Ice and water shield goes on the deck. On a tear-off we can cover the eaves, valleys or the whole deck with ice and water shield. Over shingles, it is bonding to old asphalt instead of wood.
Flat panels need a flat base. Standing seam panels are long and smooth. Lumps, curled tabs and old patches in the shingles underneath can show through.
Flashing starts fresh. Chimneys, walls, vents and valleys get new flashing tied into the new roof, not into the old one.

When going over shingles can make sense

On barns, sheds and outbuildings, exposed-fastener panels such as TuffRib and PBR are often installed over one layer of sound shingles on wood strips (purlins) that give the panels something to fasten to and leave an air gap. If the building is dry, the deck is solid and the panel maker allows it, that can be a reasonable way to save money on a building that is not a home. We will tell you honestly whether yours qualifies.

What it means for your estimate

Tear-off is part of the roof price, not a surprise. Our written estimates spell out the scope, including tear-off and how bad decking will be handled if we find it. See the metal roof cost guide for typical prices in western Ohio and eastern Indiana.

Sources

Frequently asked questions

Is it cheaper to put a metal roof over shingles?

Yes, up front, because you skip tear-off and disposal. The risk is sealing in rotten decking or wet shingles under a roof meant to last decades, which can cost far more to fix later.

How many layers of roofing can you have in Ohio?

The model code the Residential Code of Ohio follows does not allow a new roof over a roof that already has two or more layers. Your local building department has the final say.

Do you install standing seam over shingles?

No. With standing seam, Brothers Metal Roofing normally tears off all the old roofing down to the decking and replaces any bad decking before the new roof goes on.