Metal roof repair in Washington, DC

Plenty of Washington rowhouses have a projecting front bay, round or square, and the roof over that bay is often flat-seam tin or terne dating back to the original construction. Front porches on Wardman-era rowhouses in Petworth and Columbia Heights frequently have low-slope metal roofs too, as do porch roofs on Victorians in Mount Pleasant and LeDroit Park.

Steep metal shows up on turrets, mansard dormers and some main roofs on detached houses in Takoma Park and Chevy Chase. Newer standing seam roofs, painted steel or aluminum, cap additions and modern homes across the region.

Each type has its own repair method. Flat-seam tin is soldered. Standing seam panels are re-crimped and refastened at clips. Copper is soldered with a different flux and never painted.

Tin roofs are steel sheets with a thin metallic coating, and terne roofs use a similar alloy coating. Both depend on paint for long life. Once the paint wears through, rust starts at seams and low spots where water lingers, then eats pinholes through the sheet.

Small rust holes are cleaned to bright metal and soldered with a patch of the same material. Larger areas get a new sheet soldered in, with seams locked and folded the way the original was. We wire-brush or grind the surrounding rust, apply a rust-inhibiting primer made for metal roofs, and finish with a compatible topcoat.

Painting matters more than most owners expect. A well-kept terne roof can last a very long time, while a neglected one fails in a fraction of that. Most painted tin roofs we see need fresh paint every seven to ten years in DC sun.

We find a lot of bay roofs and porch roofs buried under black roofing cement or silver-painted fabric. It seemed like a quick fix at the time. The problem is that asphalt holds moisture against steel, and as it cracks it funnels water straight into the rust it was meant to cover.

Repairing a tarred metal roof means scraping the asphalt off, which is slow, then judging whether the metal under it can be saved. Sometimes it can. Sometimes the tar has hidden so much rust that a new bay roof in terne-coated stainless or copper is the better spend.

If your metal roof has already been tarred, don't add another layer. Call us before the next bucket comes out.

Standing seam roofs fail in different ways. Panels can pull loose from their clips in high wind, seams can open where they were never fully crimped, and exposed-fastener metal roofs lose their screw washers over time, leaving open holes.

We re-seat panels on their clips, re-seam with hand or power seamers, and replace failed fasteners with new screws and EPDM washers. Snow guards, pipe boots and ridge closures get checked too, since those are common leak points. Where a panel is damaged beyond saving, we fabricate a new one in the same profile and color.

If the roof is past repair, our standing seam metal roofing page covers full replacement.

Most bay and porch roofs meet a brick wall at the back, where the metal turns up and gets a counterflashing set into the mortar. That joint often fails before the roof itself does, so we repoint and reset the counterflashing when it's loose.

Bay roofs also sit right under the front box gutter on many rowhouses, and their downspouts sometimes empty onto the bay. We check that path too, since a broken downspout can dump water onto a sound bay roof and make it look like it's the one leaking.

Copper covers turret caps, bay roofs and dormer tops on some of the finest Victorian houses in the area. It doesn't rust, but it does fail: solder joints crack from expansion, thin sheets wear through where water runs over them for a century, and nails from long-ago repairs leave holes.

We clean old copper to bright metal around the damage, tin the edges and solder in a patch of matching weight. On a weathered green roof, the new copper will look bright for a while and then darken over a few seasons. Owners who want a closer match right away can have the patch chemically darkened, which we do with care so it doesn't stain the surrounding metal.

Never mix copper with steel or aluminum fasteners or flashings. Dissimilar metals corrode each other where they touch, and we often trace leaks to exactly that kind of mismatched repair. We use copper nails, copper cleats and a solder suited to copper on every copper job.