Roofing in Boston is a triple-decker problem as often as it is a shingle problem. Low-slope and flat roofs over Dorchester, South Boston, and East Boston pond at the seams and at the drains. Rubber and rolled roofing blister, open at the edge, and dump water into the top-floor ceiling. Pitched roofs in Jamaica Plain, Roslindale, and Hyde Park grow ice dams over heated stairs and bay windows. Name the shape before you name the stain.
Party walls and chimneys are the flashing details that fail. A cricket was never built behind a wide chimney, so snow sits there and melts into the attic. Roof decks screw through the membrane, and every post becomes a leak when the boot splits. Skylights over stair halls drip in a January thaw. From the sidewalk you can often see a lifted edge, a soft spot in the snowmelt pattern, or a downspout that ends in midair. Describe that.
Slate and copper still sit on Beacon Hill, the Back Bay, and parts of the South End. Those roofs fail at the nails, the valleys, and the gutters, not because the field looks thin from the street. Asphalt on a frame triple-decker is a different repair. A patch on a wet deck without finding the open seam just moves the drip. Ask whether the deck is solid enough to keep, or whether the soft wood is the real job.
Access is the quiet constraint. There may be no driveway, a narrow alley, and a rear ell over a neighbor's fence. Debris has to come down a stair that people still use. Permits and party-wall conditions change the sequence when the building touches the next one. Mention fire escapes, satellite mounts, and any solar hardware already through the roof. Those are holes the next storm will use if the flashing is tired.
Say the neighborhood, flat or pitched, and whether water is active today. A pond on a flat roof after rain is a different call from shingles in the yard after wind. Mention ice at the same eave every winter if that is the pattern. Do not send someone up blind onto a deck you know is spongy. Call the number on this page.