Roofing in Philadelphia is a rowhouse roof: low-slope or flat, parapet, seams, a drain or scupper, and flashing where the party wall comes through. Cornices leak and pretend to be a window problem. Rear additions often carry a worse roof than the main house. Some newer or larger buildings have a pitch. If you have shingles and a slope, say so. Most of these blocks do not. Ponding is the failure to describe.
Water sits, then it finds a seam, a blistered coating, or a clogged drain full of leaves from a tight block. It stains the top-floor ceiling during the rain and again later. The house next door may be pitching onto you, or your scupper may be pitching onto them. A deck, a rack, or an old coating sandwich adds holes. You can see a lot from a rear window or the neighbor's higher roof edge. Do not walk a soft spot to be sure.
Access is a bulkhead, a ladder, and a street with no side yard. Say whether the ceiling below is plaster in a bedroom someone sleeps in. Say if the roof has been coated before. Gravel or granules in the drain, a parapet joint that has opened, and a rear ell that is obviously older are the useful details. Skylights and roof decks over the stair are common leak points on renovated rows. Mention them if you have them.
Say leak, age, or storm. Ask about the deck under the covering and how water is supposed to leave. A patch in a pond, with the drain still high, comes back. If you need the leak stopped while the rest of the wet season continues, say that. Party-wall flashing is not a field patch. If the cornice is wet on the street side, say cornice, because the roof may be innocent.
This is not a steep hill roof shedding snow into a valley. Roofing in Philadelphia is the row, the parapet, and the water that will not leave. Call the number on this page.