Cool roof and rowhouse roofing in Eckington (20002)

Most Eckington rowhouses were built in the early 1900s with dark built-up or roll roofs, and many have since been covered with black modified bitumen or silver-coated patches. When you replace a low-slope roof today, DC energy rules generally expect a reflective surface. In practice that means a white or light gray membrane that bounces summer sun instead of soaking it into the top floor.

We usually install a 60-mil white TPO welded at the seams, or a granulated white cap sheet over a modified bitumen base when the owner wants a more traditional system. Either one keeps the third-floor bedroom noticeably cooler in July. Our cool roof installation page compares the options in more detail.

Insulation is the other half of the energy story. Many of these roofs have nothing between the deck and the ceiling joists. Adding a layer of polyiso board over the deck during tear-off raises the roof slightly, so we adjust the parapet flashing heights and scupper openings to match.

Eckington drains toward the combined sewer system that overflows during heavy storms, which is part of why DOEE has offered RiverSmart Rooftops rebates for green roofs across the city. A shallow sedum system adds weight, so the first question is whether the joists can carry it when saturated. We look at joist size and span from inside the top floor before suggesting it.

If the structure works, we install a root barrier over a new membrane, a drainage mat and a thin growing layer with sedum plugs or mats. Program terms and rebate amounts change, so check DOEE's current rules before counting on a rebate. Our green roof installation page lays out the build layers.

A white membrane does not fix bad flashing. The leaks we find most on blocks along R Street NE, Quincy Place and around Harry Thomas Way come from three spots: the joint at each party wall, the rear scupper and the base of the small front cornice or bay roof.

Several streets here back onto the railroad embankment and the Metropolitan Branch Trail. Rear walls facing that open stretch take more wind, and we often find lifted membrane edges and loose metal coping on that side. We refasten edges with continuous cleats and seal laps before they become a peeled roof.

Because the blocks are short and many rows were built together, your roof likely ties into your neighbor's on both sides. We cut a clean edge, lap onto their membrane and seal it so the transition stays watertight.

• Party wall seams where two different roofs meet
• Rear scuppers rusted or sized too small for summer storms
• Front cornice and bay roof transitions behind the parapet
• Old silver coating peeling over cracked roll roofing

Eckington has rear alleys on most blocks, and that is where we set up our hoist and debris trailer. Some alleys run tight beside garages and new infill houses, so we bring a shorter trailer and make extra runs. Street parking near Florida Avenue and the NoMa-Gallaudet Metro fills fast, so roll goods arrive first thing in the morning.