Box gutter repair in Washington, DC

Look at the front of a Victorian rowhouse on Capitol Hill or in Bloomingdale and you'll see a deep, ornate cornice of pressed metal or wood brackets. Behind it, set into the roof edge, is a wooden trough lined with sheet metal. The front strip of roof drains into that trough, and an outlet tube carries the water to a downspout at the front or side of the house.

Original linings were tin-plated or terne-coated steel, soldered at the seams and painted. Some houses got copper. As the paint wore off, the steel rusted; as seams cracked from heat and cold, water got into the wood box beneath. Since the gutter sits behind the cornice, nobody sees it from the sidewalk.

On many blocks the main roof drains to the rear, so the front box gutter only handles a short slope. That makes it easy to forget, and it's why leaves and silt sit in it for years.

The most common failure is a rusted-through lining at the low point near the outlet, where water sits longest. Next come split soldered seams along a long run. Both let water into the wood trough, which rots, sags and creates a new low spot that holds even more water.

The outlet itself is another weak spot. Old outlet tubes rust off at the joint with the lining, so water drops inside the cornice or down the face of the brick instead of into the downspout. Ice in a clogged outlet can push water back under the roofing at the gutter's back edge.

Past fixes cause trouble too. Layers of roofing cement and fabric over a rusty liner hold water against the steel and hide the holes. By the time we open them, the wood underneath is often soft.

Copper is the traditional upgrade. We form 16 or 20 ounce sheets to the trough shape, solder the seams, and add expansion joints on long runs so the metal can move. Copper lasts for generations and is the usual choice for front cornices in historic districts, where the gutter edge may be visible.

A membrane relining uses EPDM, TPO or modified bitumen laid into the trough and run up under the roofing at the back edge. It costs less, handles movement well, and suits gutters nobody can see from the street. It does need to wrap over the front lip under a metal edge so sun and ice don't chew at it.

Terne-coated stainless steel sits between the two. It holds paint well, solders like terne and resists rust, which makes it a good fit where the original painted look matters.

• Copper: longest life, traditional look, highest cost
• Membrane: lower cost, good for hidden gutters
• Terne-coated stainless: painted finish with strong rust resistance

A new lining is only as good as the trough under it. Once the old metal is out, we probe every board. Rotted bottom boards, sagging side walls and soft rafter tails get cut out and replaced with treated lumber or new framing sistered to sound wood.

We also reset the pitch. A box gutter should fall gently toward its outlet, and decades of sagging often leave it level or sloping the wrong way. Shims and tapered blocking restore the fall before the lining goes back.

If the cornice itself is damaged, we stabilize it from behind and coordinate any face repairs with our fascia and soffit repair work. Our article on box gutters on DC rowhouses covers seasonal care between repairs.

Every new lining gets a new outlet tube, soldered or welded to the lining and sized for the gutter's flow. A basket strainer keeps leaves out of the tube. Where the downspout below is crushed or rusted, we replace it during the same visit.

The back edge of the gutter has to tie into the roof above. On rowhouses with a front mansard, the slate or metal laps into the gutter; on flat-front houses, the low-slope membrane runs into it. We join that edge to your rowhouse roof so water never finds a gap between the two.

Built-in gutters aren't limited to rowhouses. Many older detached homes in Takoma Park, Cleveland Park and parts of Montgomery County have Yankee gutters or pole gutters built into the lower edge of the roof. They fail in the same ways: rusted linings, split seams, rot in the wood behind them.

On those houses the gutter often runs around corners and over porches, which adds miters and expansion joints to the lining. We form and solder those corners on site, and we check where each downspout lands so water doesn't end up back against the foundation.