How to Choose a Metal Roofing Manufacturer

What makes a good metal roofing manufacturer?

A good metal roofing manufacturer makes a durable product, puts clear warranties behind it in writing, has it independently tested, and controls how it is installed. Brand recognition is not on that list. A familiar name tells you little about how a specific roof will perform on a Cape in Barnstable or a farmhouse in the Upper Valley. Start with the product itself: the metal, the coating, and the panel design. Then look at the paperwork: warranty terms, test listings and code evaluation reports. Finally, look at the installation model. A manufacturer that trains and certifies its installers, and limits who can sell and install its system, has more control over the result than one whose panels can be bought by anyone and installed by anyone.

Does the type of metal matter in New England?

Yes, the metal matters, especially near the coast. Steel roofing relies on a metallic and paint coating to keep the iron in the steel from rusting. That approach works well in many places, but scratches and cut edges are exposed, and salt air speeds up corrosion where the coating is breached. Aluminum has no iron, so it cannot rust. It forms a thin oxide film that protects the surface. For homes on Cape Cod, the Islands, the North Shore, the Rhode Island and Connecticut shoreline and the Maine coast, that is a meaningful difference. Aluminum is also light. Interlock® panels weigh roughly 0.4 to 0.7 lb per square foot, which suits older framing under New England snow loads. Ask any manufacturer how its metal behaves in your specific setting.

What should you look for in a metal roof warranty?

Look at who is covered, for how long, what is covered, and what is excluded. A long-term warranty should state exactly whose ownership it follows and what limits apply. Check whether coverage transfers if you sell, and how many times. Check whether the finish is covered separately. Confirm that workmanship is handled somewhere, since material warranties usually exclude it. As an example of the details to look for: Interlock® roofs carry the Guardian Lifetime Limited Material Warranty, which covers material and finish for the original purchaser while they own the home, transferable once, with the second owner covered to 50 years from substantial completion. The finish has a 30 Year Alunar® coating warranty. Ice damming is excluded.

Which independent ratings and code reports should you ask for?

Ask for the listings and reports themselves, and check which products they cover. Common ones for metal roofing include wind ratings, impact ratings under UL 2218, fire ratings under ASTM E108 / UL 790, and code evaluation reports from ICC-ES that show how a product meets building code requirements. Details matter. Interlock® shingles are rated for winds up to 120 mph when installed to manufacturer specification. Their UL 2218 Class 4 impact rating is held through a listing issued by Intertek for Delta Building Products. Fire performance is described as Class A Fire Rated Available, as a complete assembly, meaning the rating applies to the tested assembly rather than the panel alone. ICC-ES evaluation report ESR-1790 covers the shingle, slate, shake and tile profiles.

Why does panel design matter for wind and water?

Panel design matters because it decides where water and wind can get in. Systems with exposed fasteners put a screw and rubber washer through the face of the metal at every attachment point, and those washers age. Interlocking, concealed-fastener systems hide the fasteners under the next course and lock each panel to its neighbors. In a nor'easter, rain is driven sideways and up the slope, and gusts look for loose edges. An interlocking panel with formed joints and no free tabs handles both better than a lapped design. Also ask how the manufacturer designs its flashing and trim for chimneys, walls, skylights and valleys, because on any roof those are the places leaks begin. A complete system with matching parts beats improvised details.

Who installs the roof, and who is accountable?

The installer is as important as the manufacturer, so find out exactly who will put the roof on and who answers if something goes wrong. Some manufacturers sell through distributors to any contractor. Others work only through certified installers trained on their system. Interlock® roofing is sold and installed only through the certified exclusive installer in each region. In New England, that is Interlock Metal Roofing (New England) Inc., which has installed 5,036 Interlock® roofs across the six states since 1999. Whoever you consider, check state registration: Massachusetts home improvement contractors register under M.G.L. c. 142A, Connecticut contractors with the Department of Consumer Protection, and Rhode Island contractors with the Contractors' Registration and Licensing Board. New Hampshire and Maine have no state roofing license, so references count for more there.

Step by step

1. Decide which metal suits your house and location.
2. Collect the full warranty documents, not brochure summaries.
3. Ask for independent test listings and code evaluation reports.
4. Compare how each system handles fasteners, joints and flashing.
5. Confirm who installs the roof and check their state registration.
6. Look at finished roofs on houses like yours.

Common questions