Windows in Baltimore are mostly the front and back of a rowhouse, because the side walls are often shared and have little glass at all. Original wood sash, tall and painted, still faces plenty of streets, with cords that failed and meeting rails that no longer lock. Alley windows and basement hoppers take abuse from splash, trash, and a lack of sun. Harbor humidity swells the wood in summer. A winter draft finds every gap in a single-pane sash that has been painted shut for years.
The frame and the brick opening matter as much as the glass. Formstone or a later skin around an old opening can trap water at the trim. A milky insulated unit in a newer insert is a different problem from a rotten sill under a sash that still has weights. If the stool inside is soft, the wall has been taking water and a fresh sash alone will not finish the job.
Street noise, a dark middle room, and a top-floor sash that bakes in the afternoon are all fair reasons to call, and they are not the same job. A bath window that sweats onto old plaster is a moisture problem tied to the room as much as to the glass. End units have a side wall of windows that mid-block houses never had, and that wall takes the weather. Say which face of the house is failing, and whether the sash moves or is painted into one position.
You do not need every opening counted before the call. Say front facade, rear wall, basement, or the whole house. Mention trim you want kept, a pulley window you hope to repair rather than scrap, or glass that has gone opaque. Old paint on a sash that has to be disturbed belongs in the description so the work is handled with the right care.
Look at the lower rail and the inside stool. Baltimore windows fail where wood, brick, and damp air meet, and on rows where the sides of the house cannot help with light or air. Bring the wall and the symptom, and say if the house is mid-block or on the end. Call the number on this page.