Why Union City roofs fail the way they do
The defining feature of a Union City roof is that most of them are flat or low-slope, and flat roofs fail on completely different terms than the pitched roofs in the suburbs. A pitched roof sheds water fast, so its weak points are the flashing and the shingle field. A flat roof does the opposite. Water sits on it, finds the slightest low spot, and works patiently at every seam, blister, and failed flashing detail until it gets through. On the older built-up and single-ply membranes common across the city, we routinely find spots where the membrane has shrunk and pulled away at the edges, drains that have clogged and let water pond, and parapet flashing that cracked years ago and was caulked over instead of rebuilt. A single bad seam can let in a remarkable volume of water before anyone downstairs sees a stain.
The density makes everything harder. When buildings share party walls and parapets, water that gets past one roof can travel into the structure next door, and the flashing at every wall transition becomes a likely entry point as the original metal corrodes. On top of that, the full range of a New Jersey year goes to work on these roofs. Humid summers bake the membrane and the rooftop equipment, the heavy summer thunderstorms and the soaking fall nor'easters dump water faster than a clogged drain can clear it, and the winter freeze-thaw cycle pries open every small crack and works ice into the seams. A flat roof in this climate is fighting standing water, sun, and ice all at once, which is exactly why so many of them leak.