Skylight and Vent Flashing Repair in Hempstead, NY

Why do openings in the roof leak first?

Because the flashing around an opening is more complex than the rest of the roof, with several joints that must all be sealed. A single failed joint is enough for water to get in.

A skylight has a frame, a curb and a flange, and each joint must be sealed to the roof covering. A vent pipe has a collar and a flashing that must seal against the pipe and the shingles. A hatch has its own frame and gasket. Each of those joints can fail separately, and the failure often starts at a corner where two pieces meet.

Wind-driven rain pushes water into those corners, and the seal is tested by the movement of the roof. A joint that has been sealed with a dried sealant is the first to fail in a storm.

Why is the decking beneath an opening checked?

Because a leak at an opening can run down the frame and soak the decking beneath it. Soft wood will not hold new flashing, and it has to be replaced first.

Water that gets past a skylight or a vent often runs along the frame and onto the decking below. Over time the decking softens and darkens, and the fixings for the new flashing lose their grip. The roofer checks the boards around the opening from the attic and the roof, and replaces the soft ones.

The check is important because the leak may have been running for some time without showing in the room below. A flashing repair on soft decking will fail, and the note records what was found.

What is a seal test and why is it used?

A controlled amount of water is run around the joint from a safe position to see where it gets past the flashing. The test shows the gap without waiting for the next storm.

Water is run around the edges of the skylight or the vent, and the attic is watched for the first sign of water. The test finds the gap that the storm would find, and it shows which part of the joint needs repair. A repair that is not tested can still leak in the next storm.

The test is done from a safe position on the roof, and it is recorded in the note. A homeowner who sees the test should ask the roofer to show the gap that was found.

What should a homeowner check after a storm?

The openings from the ground and from inside. A stain beside a vent or a drip near a skylight after rain is a sign to call.

From the ground, look at the vent pipes and the skylights for cracked collars, lifted flashing or dried sealant. Inside, check the ceilings below the openings for new stains, and the attic for damp wood beside the vent pipes.

Report any sign with the date and place. The note from the repair lists each opening and its condition, so the next check can start from there.

• Look at each vent collar for cracks
• Look at each skylight frame for lifted flashing
• Check the ceilings below the openings after rain
• Check the attic beside vent pipes for damp wood

Why does the skylight curb matter as much as the glass?

The curb is the raised frame the skylight sits on, and its flashing carries the water around the glass. A curb with a failed corner leaks even when the glass is sound.

A skylight curb is a box built up from the roof, with flashing set into the roof covering on all four sides. Water runs down the slope to the upper edge of the curb, and the flashing there directs it around the sides. A failed corner or a lifted flange lets the water in beside the glass rather than through it.

The roofer checks each corner of the curb from the roof and the attic, and checks the glazing seal where it meets the frame. Repairing the curb flashing is often the whole fix, and the glass is left in place when it is sound.

What about roof hatches and their gaskets?

A roof hatch has its own frame, lid and gasket, and each can fail on its own. The gasket is the part that dries and cracks first, and the frame must be checked with the flashing.

A hatch sits in a frame that is flashed into the roof covering, and its lid closes onto a gasket. In sun and frost the gasket dries and cracks, and a storm can drive water past it. The leak then runs down the frame and into the room below the hatch, which is often missed because the water shows some distance away.

The roofer checks the gasket and the frame together, renews the gasket where it has failed and checks the flashing beneath the frame. The seal is tested with water, and the note records the hatch and the test.