Windows in Boston mark the age of the block. Triple-deckers carry bay windows that rack in the wind and leak at the angle where the bay meets the main wall. Brick openings in the South End and on Beacon Hill are not stock sizes, and the sash may still hang on cords and weights. Alley windows on the second means of egress get painted shut. Say which face of the building takes the harbor wind and which face never sees the sun.
A draft at a meeting rail, a rotten sill under a kitchen bay, and a vinyl unit that was foamed into a crooked opening are three different jobs. The vinyl that covered old trim sometimes trapped water against the original frame, so the pretty outside hides mush. Storms that do not latch will buzz all winter on a Jamaica Plain hill and do nothing for the sill. Look for stains on the apron and swelling on the stool.
East Boston, Charlestown, and South Boston take salt. Paint fails, putty falls out, and the sill checks faster than the same window in Roslindale. Condensation on a single pane in a steamy kitchen is often the cooking and the lack of a fan, not a reason to replace every opening on the street front. A fogged insulated unit is a failed seal and a smaller conversation. Know which one you have before you call.
Replacing a bay is not the same as replacing one double-hung on the side wall. The roof of the bay, the seat, and the trim inside may all be part of the water path. Historic brick blocks may need the sightlines kept, which means repair of sash rather than a new frame that sticks out past the molding. Ask that question if you are in a row where the windows are part of the street wall. Measure nothing yourself if the sash is painted shut and rotten. Just describe it.
Count the bad openings and name the rooms. Mention bays, storms, and any window that is also a required way out and must still open. Have the neighborhood and the building type, triple-decker or brick row or freestanding house. A clear list beats a speech about drafts in general. Call the number on this page.