Roof flashing repair where Jersey City leaks actually start

The open area of a roof, the field, is one continuous sheet. It sits flat, gets the same sun everywhere and moves very little. Flashing is different. It's wherever the roof meets something else: a wall, a parapet, a pipe, a chimney, a hatch, a skylight, a rooftop unit. Those spots move at a different rate than the roof, get hit by splash and ponding, and are built from several pieces lapped together by hand. That makes them the weak link.

On older Jersey City roofs, flashing is often the most patched part of the system. Layers of mastic get troweled over cracked base flashing every few years until the original detail is buried. Mastic dries in the sun, cracks and holds water against the wall. When we take a leak call, the flashing is where our crew looks first, because that's where the answer usually is. And the water doesn't always appear right below: a failed wall flashing can run inside the masonry and show up a floor or two down.

On a flat roof, base flashing is the membrane turned up a wall or parapet. Counterflashing is the metal that covers the top of it, set into a reglet (a slot cut into the mortar) or fastened to the wall and sealed. A termination bar holds the top edge of the base flashing tight. Curbs around hatches, skylights and rooftop units are flashed the same way, with membrane wrapped up the sides and capped.

Pipes get pipe boots or flashing collars. Odd-shaped penetrations like structural steel or clusters of conduit sometimes get a pitch pocket, a small box filled with sealant. Pitch pockets need regular topping off as the filler shrinks, and they're a frequent leak source on older roofs, especially where satellite dish or antenna mounts were left behind after the equipment came down.

Skylights and chimneys combine several of these details at once, and each has its own page: skylight leak repair for curbs and domes, and chimney leak repair for crowns, caps and the brick itself. Here is the full list of flashing details we inspect on a leak call:

• Base flashing at walls and parapets
• Counterflashing in reglets or surface-mounted
• Termination bars at the top of upturns
• Pipe boots and flashing collars
• Pitch pockets around odd penetrations
• Curb flashing at hatches, skylights and units
• Scupper and drain flashing at the roof edge

Freeze-thaw is hard on flashing. Water gets into a small gap at the top of a base flashing, freezes, and pries it a little wider every winter. Sun bakes rubber pipe boots until they crack around the collar. Wind lifts loose counterflashing and bends it away from the wall, and nor'easters drive rain right into the opening. Near the waterfront, salt air speeds corrosion on older metal flashings and fasteners.

Rooftop units are a special case. On condo and walk-up roofs, air conditioning condensers and exhaust fans get replaced, moved or added over the years, and the curb flashing is often disturbed in the process and never properly rebuilt. If a leak started after equipment work, the curb is the first thing we check.

Another common failure is base flashing that simply stops too low. If it's only a few inches tall, ponding water or packed snow can rise over it. On these roofs, raising the flashing is part of a lasting repair, and it often goes hand in hand with parapet waterproofing when the wall above is also taking water.

A real flashing repair means removing the failed piece and the mastic buried around it, down to a clean surface. We then install new base flashing at the correct height, fasten it under a termination bar, and seal the top with counterflashing let into a reglet or mounted and sealed to the wall. Pipe boots are replaced with new boots sized for the pipe, and pitch pockets are rebuilt or replaced with a prefabricated cover where possible.

We match materials to the roof. A modified bitumen roof gets compatible modified flashing; an EPDM or TPO roof gets compatible membrane and accessories; on cluttered details a reinforced liquid flashing often wraps better than any sheet. Mixing incompatible products is a common cause of early failure. If flashings are failing all around the roof, we'll talk with you about full roof waterproofing instead of one repair at a time. Either way, you get photos of the failed detail and the finished repair.