When a roof leaks, a homeowner's thoughts may instantly turn to damaged shingles or flashing, but these are not the only potential culprits. A roof is pierced in a number of places for the sake of ventilating the attic space as well as waste stacks. Waste stack vents are the pipes that stick up from the roof and are sealed to the roof with a rubber gasket mounted on a metal plate, called a boot or a collar, at the base of the pipe. After years of exposure to sun and rain, the rubber can rot and crack, allowing water to seep into your home around the vent stack.
Things You'll Need
- Extension ladder
- Rubber rain collar
- Vent boot
- Roofing cement
- Nail pry bar
- Roofing nails
- Galvanized screws with rubber washers
Climb onto the roof using an extension ladder with ends that extend at least 3 feet above the roofline to provide a safe hold when getting on and off the roof.
Examine the existing rubber collar around the ventilation stack for cracks and holes. Leave the collar in place.
Slip a rubber rain collar of the correct diameter over the pipe. A rain collar is a gasket alone with a base long and wide enough to extend over the existing gasket.
Tug the rain collar all the way down to meet the metal flashing. The rubber gasket should fit tightly around the circumference of the pipe and be flush with the flashing at the bottom so any rain sheds over the existing, damaged gasket. No caulk or roofing cement is required. This is designed to be a temporary fix to stop an ongoing leak.
Climb onto the roof, as in Section 1, with your tools, roofing cement and a rubber boot with attached flashing. This style of boot has a raised section of flashing in the center of a flat square of flashing with the rubber gasket at its center.
Flip back the shingles two courses above and immediately behind the vent stack. Carefully remove the roofing nails from the top of the course of shingles right behind the stack with the nail pry bar. These shingles often have a U-shaped cutout to fit around the original boot and extend down its sides.
Pull out any roofing nails installed in the bottom corners of the flashing of the original boot with the nail pry bar. Pull the assembly up and off the vent stack.
Pull the new boot with attached flashing down over the vent pipe until the flat square of flashing is flush with the roof sheathing. Lift the shingles above the vent as you lower the boot near the roof to slide the upper part of the new boot's flashing under the shingles above.
Drill small holes through the guide holes at the bottom edge of the boot flashing with a drill. Fasten it down through the holes with galvanized screws backed with rubber washers using the appropriate screwdriver.
Apply roofing cement in a semicircle around the top of the boot flashing, running the bead of cement halfway down each side.
Slip the side shingles back into place under the course above the vent stack, pressing them into the roofing cement, and tack them into place under the course of shingles above with roofing nails and a hammer.
Tips & Warnings
- Use a roofing safety harness if your roof is steep or above a second story.
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