What Is Copper Roofing? A Guide for New England Homeowners

What exactly is a copper roof?

A copper roof is a roof covering made from solid copper sheet, shaped into panels or units and fastened with concealed clips or compatible fasteners. The copper is the same metal all the way through, so there is no paint or coating to wear off. Copper is soft and easy to form, which is why it can wrap domes, cones and curves. It is sold by weight in ounces per square foot, with 16-ounce and 20-ounce sheet being common for roofs. Copper can cover an entire roof or a small part of one. Many New England homes use it only on a bay window, porch roof, cupola or entry, or as flashing around chimneys and valleys. A full copper roof is less common on houses because of cost, but it remains a traditional choice for churches, civic buildings and landmark homes.

How has copper been used on New England buildings?

Copper has been used on New England buildings since the early years of the republic, especially on domes, steeples and civic roofs. In 1801 Paul Revere opened a copper rolling mill in Canton, Massachusetts, one of the first in the country, and his company provided copper sheathing for the dome of the Massachusetts State House in 1802. The dome was gilded decades later, but the copper is part of its story. Through the 1800s and 1900s, copper appeared on church spires, town halls, college buildings and the bays and cupolas of Victorian and Shingle Style houses along the coast. Many of those roofs and accents are still in place, now a deep green. That history is why copper fits so naturally on older New England houses, and why owners of historic homes so often ask about it.

How does copper change color over time?

Copper changes from bright salmon-pink to brown within months, and then, over years or decades, to the blue-green patina seen on old steeples. The color shift comes from slow chemical reactions with oxygen, moisture and airborne sulfur and salt. The patina is protective. It bonds to the metal and slows further corrosion, so copper does not need paint or sealant to last. On the coast, salt air and frequent moisture generally move the process along faster; in drier, sheltered spots it takes longer. One side effect is runoff. Rain from a copper roof carries trace copper that can stain light siding, trim and stone, and it can corrode aluminum or galvanized steel it drains onto. Our article on copper patina explains the stages and the options for slowing or speeding them in more detail.

What are the main benefits of copper roofing?

The main benefits of copper are a very long service life, natural corrosion resistance and a look that many owners feel improves with age. Copper does not rust, holds up well in salt air and stays ductile in cold weather, which suits New England's coastal and winter conditions. It is also relatively light. A 16-ounce copper sheet weighs about 1 pound per square foot, much lighter than natural slate, which can make it easier to use on older framing. Copper can be shaped into forms other materials cannot follow, and it is fully recyclable. The tradeoffs are real: copper is expensive, its price moves with commodity markets, it needs installers who know how to work with it, and it must be kept away from incompatible metals. Our copper pros and cons article covers each of those in detail.

How does copper compare with aluminum roofing?

Copper and aluminum are both non-rusting metals that perform well in New England's coastal and winter conditions; the differences are cost, weight, appearance and how they age. Copper is far more expensive, heavier and changes color over time. Aluminum is lighter, roughly 0.4 to 0.7 pounds per square foot for Interlock panels, and its factory finish keeps a consistent color. Interlock makes both. Solid copper is available in Interlock profiles for owners who want the real metal and its patina. For owners who want a copper tone without patina, the Copper Penny color is offered on aluminum. Other aluminum colors include Hunter Green, Black, Deep Charcoal, Tile Red, Colonial Brown and Tudor Brown. Mixing the two is common, with copper on a bay or entry and aluminum on the main roof, as long as drainage keeps copper runoff off the aluminum.

Who installs copper roofing in New England?

Copper roofing is installed by roofing contractors and sheet-metal specialists with experience forming, seaming and soldering copper. It is a narrower trade than asphalt roofing, so ask any contractor to show completed copper work, not just general roofing photos. Interlock Metal Roofing (New England) Inc. is the certified and exclusive Interlock roofing contractor for New England, working from Walpole, Massachusetts, and serving Massachusetts, New Hampshire, Connecticut, Rhode Island, Maine and Vermont. We install Interlock solid copper and copper-colored aluminum systems. As with any roofing project, check the contractor's state registration where it applies, such as Massachusetts or Connecticut Home Improvement Contractor registration or Rhode Island Contractors' Registration and Licensing Board registration, and ask for current insurance certificates. If you are in a historic district, check with your local historic district commission before committing to a material.

Common questions