Can You Replace a Slate Roof With Metal?

Can a slate roof be replaced with a metal roof?

Yes. Replacing a failing slate roof with metal is common across New England, and the most popular choice is a metal slate profile that keeps the look of the original. Interlock's Slate profile is the one we install most often in the region. The key point is that this is a full replacement. Every slate, along with the old felt and flashings, is removed down to the roof deck before anything new goes on. Owners usually reach this decision when the roof needs more than spot repairs: slates are slipping because the nails have rusted through, flashings around chimneys and valleys are leaking, or broken pieces keep showing up in the yard after storms. At that stage the choice is between a new slate roof and an alternative, and metal is often the more practical one.

Can you put a metal roof over existing slate?

No. Metal roofing should never be installed over natural slate, and Interlock requires the slate to be removed. Slate is brittle and uneven, so fastening through it cracks the stone and leaves the new roof sitting on a surface that keeps shifting. There are other reasons too. The combined weight of the slate plus a new roof adds load the framing does not need. Old slate hides the deck, so rot, broken boards or past leak damage stay out of sight. And leaving the old flashings in place means the new roof inherits their problems. Tear-off also lets the crew install new underlayment and ice barrier at the eaves and in valleys, which matters on any roof that sees New England snow. It costs more than an overlay would, but it is the only sound way to do the job.

Why do New England owners replace slate with metal instead of new slate?

Most choose metal because it gives them the slate look with far less weight, less fragility and a lower overall cost than a new natural slate roof. New slate is an excellent material, but it is heavy, slow to install and needs a roofer with slate experience. Weight is the biggest factor on many homes. Aluminum slate panels weigh roughly 0.4 to 0.7 lb per square foot, while natural slate is many times heavier. Removing that load is welcome on older framing that also has to carry heavy, wet snow. Metal also avoids the repair pattern slate owners know well: cracked pieces from ice or branches, and the risk of breaking more slate whenever someone walks the roof to fix a chimney or antenna. An aluminum roof can be walked carefully without damage.

What does the replacement process look like?

A slate-to-metal replacement starts with an inspection of the roof, deck and attic, so you know before work begins whether framing or decking needs repair. That inspection is also when we look at attic ventilation and insulation. On installation day the crew strips the slate, old underlayment and flashings, and sets up protection for gardens, siding and driveways. Slate is heavy and sharp, so debris handling and site cleanup take real effort. Once the deck is open, damaged boards are replaced and the surface is prepared. Then come underlayment, ice barrier where needed, new flashings at chimneys, walls and valleys, edge and ridge trim, and the interlocking metal panels. The timeline depends on roof size, complexity and weather, and we give you a schedule specific to your house rather than a generic number.

Do historic district rules apply when replacing slate?

They may. Slate roofs are common on older homes in local historic districts, and many commissions review roof replacements that change the material, especially when the roof is visible from a public way. Some commissions require replacing slate with slate. Others accept materials that match the original appearance. Many decide case by case and want to see samples, photos and product information first. Check with your local historic district commission before you sign a roofing contract, and ask exactly what they need. We can supply samples and documentation for the application, but we cannot promise an outcome. Condominium owners should also check with their trustees or board, since roofs are usually common area. Building permits for re-roofing are typically required, and your contractor should pull them.

What should you look for in a contractor for a slate tear-off?

Look for a contractor who is properly registered in your state, carries insurance, and has experience removing slate safely. In Massachusetts, home improvement contractors working on owner-occupied homes must register under M.G.L. c. 142A; Connecticut requires Home Improvement Contractor registration with the Department of Consumer Protection; Rhode Island registers contractors through its Contractors' Registration and Licensing Board. New Hampshire and Maine have no state roofing license, so in those states references and insurance certificates matter even more. Ask how the crew protects the house during tear-off, how they handle flashings at chimneys, and what happens if the deck needs repair. Older homes built before 1978 may involve lead-safe work practices for some exterior tasks. A written contract that spells out scope and warranty terms is essential for any roof.

Step by step

1. Have the roof, deck and attic inspected.
2. Check with your local historic district commission or condo board if either applies.
3. Choose the profile and color using outdoor samples.
4. Remove the slate, old underlayment and flashings.
5. Repair or replace damaged decking.
6. Install underlayment, flashing, trim and the metal roof.
7. Walk the finished roof and site with the crew lead.

Common questions