Install roof plumbing vent flashing

I might have pull up the insulation to look at the attic side of the ceiling drywall to be sure it wasn't moldy. It may not be significant but a closer look at the plumbing vent boot flashing above shows that the rubber seal has slipped down from its original position, possibly due to snow loading or due to simple aging of the rubber. Sometimes when there is wet snow on the roof, if the rubber seal has aged, dried, hardened, we may see a bit of leakage around the vent pipe in this location.

That would be in addition to the condensation and frost we've already noted, but it could also be related: if the plumbing vent does not seal around the vent pipe then air leaks at that location increase the movement of moist warm attic air up and out around the vent flashing, increasing the rate of condensation and frost formation on the vent pipe.

Also notice in my enlargement of your photo those two nails at the bottom of the vent boot flashing are not a recommended practice as they puncture the metal flashing to form possible leak points. In your photo we see two face nails, sealed atop the flashing. We can't see if sealant was used below the flashing at those nail punctures but in the attic we don't notice leak stains at that corresponding location. That's probably not a leak point.

That sort of leak can happen in particular in a climate such as yours North New Jersey where there may be wet snow or even ice dams on roofs in winter. It's not a major crime and I wouldn't be tearing up the roof to fix it, especially this time of year.

But if we see recurrent or worse leaks at the plumbing vent flashing we might decide to seal that flashing more-carefully against side leakage. Take a look again at the roof deck inside, along the opening cut into the roof to see if the stains suggest that there has been water entering along the vent boot flashing sides. On your photo of the roof exterior I have indicated in yellow [photo above] that the actual plumbing vent boot flashing is a bit more-exposed along the sides than is preferred to avoid leaks.

The top shingle's bottom edge is too high at this plumbing boot installation. Best practice would be for the vent flashing sides to be below shingles to a point below the lower edge of the vent pipe itself - the "Preferred" line in my photo annotations. Roof safety guidelines As with any plumbing installation, safety must be a top priority when installing or repairing roof flashing. Take the following precautions to reduce your risk of having an accident: Tread lightly.

Roofs are not designed to handle regular foot traffic. Wind, rain, snow and ice can make it harder to maintain your footing. Identify hazards. Before work begins, clear the roof surface of any potential tripping or slipping hazards, such as fallen branches, leaves, tools or other materials.

Flag any skylight locations. Depending on the home, you may also need to be aware of overhead power lines, exposed wires, conduit or solar panels. Stick to the essentials.

Keep all other tools or materials off the roof. If you are replacing an existing flashing, you will need a flat bar to assist in shingle removal. Practice ladder safety. The ladder you use to get on the roof should be tied off or secured to the building to prevent it from shifting. Stay hydrated. Because a roof is designed to reflect heat, workers can easily become dehydrated on hot days.

Drink plenty of water to avoid dizziness or lightheadedness that may lead to falls and other accidents. Install a single tab along the course of shingles to rearrange them so that there is not a shingle joint directly above the pipe. Continue shingling above and around the pipe trimming the shingles when necessary to fit around the pipe.

Nail the shingles over the vent pipe to insure no nails go through the flashing. Allow about a hald inch space between the shingle and the sleeve when trimming the shingles. For additional protection of low-sloped roofs you can embed a strip of mineral rolled roofing in roofing cement under the flange.

When installing larger vents such as heater vents or off-ridge-vent you must nail down the lower edge of the vent. Apply roofing cement along the flange. Install shingle shingle around the vent trimming them when necessary.