Historic Metal Roof Restoration in Charleston, SC

Paint is what keeps a terne or tin roof alive. The National Park Service's guide to historic roofing notes that tin roofs were kept well painted, usually red, and that any iron-based roofing needs an undercoat and a well-kept paint surface to stop corrosion. Once the plating is worn through, bare iron rusts.

A repaint is more than a color coat. Ask for loose paint and rust to be removed by hand, for a primer suited to terne and steel, and for the finish coat to be named in the estimate. Our view: a repaint done on time is the cheapest roofing work an old house will ever get.

The Park Service notes that metal fatigue shows up at the joints and at anything that pokes through the roof, so seams, chimneys and vents are where a restoration starts. Opened seams get cleaned and re-soldered, and small holes get a soldered patch of a compatible metal. Often most of the sheet is still sound.

Two cautions from the Park Service guide are worth putting to any roofer. Patching a metal roof with caulk or asphalt compound is harmful and at best temporary: asphalt cracks as it hardens, blisters, and holds water against the metal, and it is hard to remove later. And soldering is a fire risk, from the open flame or from the old wood underneath overheating and smoldering unseen. Ask how the crew guards against that and how long someone checks the roof after the torch goes out.

When a historic standing seam roof is past repair, the BAR expects it to be replaced in kind, built the way the original was. Standing seams on historic buildings have to be traditional hand-crimped detailing. Snap-lock panels and commercial-grade metal roofs are not approved.

In practice that means pans with seams turned by hand tools, not a factory panel that clicks together. Not every metal roofer does this work, so mention the BAR district when you call, and ask on the visit how the seams will be formed.

The BAR policy expects that terne metal won't always be available. If terne can't be had, BAR staff may sign off on aluminum or coated copper as the in-kind material. Staff can also approve replacing standing-seam terne with uncoated standing-seam copper, except on Category 1 and Category 2 buildings, where that swap is off the table.

The Park Service lists other substitutes for tin and terne: lead-coated copper, terne-coated steel and aluminum-zinc coated steel. It also warns that copper-coated steel is a cheaper but less durable stand-in for sheet copper. Copper's own details, from weight to patina, are on our copper roofing page.

Some older roofs, porch roofs and bays carry small stamped tin shingles, embossed to look like wood or tile or with a decorative pattern. They were an inexpensive textured roof in their day, and they lock together at the edges. The Park Service notes that many have been repaired by nailing through the face, which can cause leaks. A good repair replaces damaged shingles with matching interlocking pieces rather than nailing through them.