Roofing in New Jersey has to name the roof, because the state refuses to have just one. Shore houses take wind and salt: tabs lift, metal flashing pits, and rain is driven uphill under the edge. Inland and north, ice at the eaves and a snow load still matter, especially on older pitched roofs. In the dense cities, low-slope and flat roofs with parapets pond water the way a simple gable does not. Say which roof is leaking before you describe the stain.
The leak's timing is the clue. Wind-driven rain on the shore shows up on the wall as often as on the ceiling. A flat roof in a tight block drips during the storm and again later, while a pond sits over a seam or a clogged drain. An inland ice dam wets the attic when the sun hits the slope and the gutter is ice. Granules in the downspout and a rusty chimney flashing are worth saying. Do not climb a wet slope or a soft flat roof to improve the story.
Neighbors are close. Their roof may pitch water onto yours. A party-wall flashing may be the open joint. A tree on a small lot may be scouring the same spot every wind. Say if the covering has been coated before, and if the coating is what cracked. Say if there is a deck, a solar rack, or a swamp of leaves because the roof is hidden behind a parapet. Access on a tight lot is a ladder from a narrow side yard or from the street. Mention that.
Say leak, age, or storm. Say shingle, membrane, or you do not know. Ask about the deck, the underlayment at the eaves where ice is the pattern, and the flashing at walls and chimneys. A patch that does not name how water leaves the roof will fail in the next nor'easter. If you only need a dry-in so the ceiling stops getting worse, say that, and say whether the rest of the season is still wet.
A beach gable, an inland colonial, and a city flat roof are three jobs. Roofing in New Jersey starts when you pick the one you are standing under. Call the number on this page.