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How to Repair Bad Vent Pipe Flashing

Vent Pipe
The roof is your home's first line of defense against one of the most destructive of all natural substances: water. By redirecting water safely away from your home, a roof acts to prevent all manner of structural damage. Of course, if your roof should develop a pesky leak, you may find yourself having to shell out top dollar for costly repairs.

To avoid serious damage to your roof, arm yourself with information about where and how water manages to penetrate a roof. If you would like to improve your knowledge of common leak sites, read on. This article will introduce you to one of the most frequently encountered sources of roof leaks: vent pipe flashing.

Plumbing Vents

Virtually every single home in America contains one or more plumbing vents that come up through the roof. By connecting your plumbing system to the open air, these pipes serve an important purpose: preventing water from being siphoned out of your plumbing traps each time you use the water. The plumbing vents, in turn, prevent noxious sewer gases from rising up into your home.

Vent Boots

As with any other structure passing up through the surface of a roof, your plumbing vent pipe needs to be sealed off so that water cannot sneak past into your home. As with all roofing structures, you can seal off your plumbing vents through the use of flashing. The type of flashing used is known as either vent pipe flashing or, more simply, a vent boot.

The vent boot is designed to closely surround the pipe and sit flush with the surface of the roof. Boots are commonly constructed out of either rigid plastic or a corrosion resistant metal such as aluminum. Beneath the boot itself is a second, equally important component, known as the rubber gasket. The gasket is responsible for providing a watertight seal between the outside of the vent pipe and the inside of the vent boot.


While designed to provide water protection for many years, vent boots are still prone to developing a variety of problems that can lead to leaks. One of the most common issues you will encounter involves a vent boot that has physically worked loose from the surface of your roof. A loose vent boot will allow water to trickle in beneath the perimeter of the boot.

Vent boots are generally loosened by roofing nails that have worked themselves loose. They may even be completely missing. Fortunately, the solution is fairly simple: install new fasteners. Rather than using more nails, experienced roofers will often secure the vent boot using rubber washer screws. Rubber washer screws are not only less likely to come loose over time but also equipped with an integrated rubber washer that will prevent water from leaking in around the screw's shank.

Vent flashing leaks may also stem from problems with the rubber gasket installed beneath the boot. Rubber gasket issues tend to involve rubber that has become cracked and degraded over time - a common phenomenon, given that the gasket is regularly exposed to destructive elements such as rain and sun, as well as extreme temperature fluctuations.

If there is no problem with the boot itself, a roofing company can often remedy the leak simply by replacing just the gasket. However, many vent flashing leaks also involve a vent boot that has become damaged. Boots made of plastic tend to involve the formation of cracks. Metal boots, on the other hand, tend to split open along their seams.

Bottom Line

Vent flashing that has suffered damage or reached the end of its lifespan can put your home at serious risk. Therefore it is important that you have your vent flashing inspected for signs of trouble on a regular basis. For more information about this important maintenance effort, please don't hesitate to contact the experts at Carroll Roofing Company, Inc.