On a rooftop, any seam or obtrusion is susceptible to water leaks and damage. To prevent leaking, install metal flashing along roof valleys and over vent pipes. The vent pipe flashing is a specialized building material with a tubular piece of metal attached to a wide base, or flange. On a shingle roof, vent pipe flashing should be positioned so it overlaps the lower course of shingles and is overlapped by the shingle courses above. In this way, a continuous water-resistant membrane forms over the rooftop.
Things You'll Need
- Corrosion-resistant roofing nails
- Vent pipe flashing
- Roofing sealant
- Utility knife
Fasten shingles to the roof until you reach the vent pipe. Nail each shingle with two corrosion-resistant nails.
Set the vent pipe flashing in place to check the fit. Make sure the base of the flashing extends onto the portion of the shingle course it overlaps.
Fasten the flashing with corrosion-resistant roofing nails.
Seal the edges of the vent pipe flashing and the nail holes with roof sealant.
Install the next course of shingles. Where the shingle pattern intersects the vent pipe, mark the shingle with a pencil. Then use a utility knife to cut a notch into the shingle so it can fit snugly around the extension of the vent pipe and flashing.
Fold the top of the vent pipe flashing down into the vent pipe to create a cohesive, water-resistant barrier.
Continue to fasten the roofing shingles. Maintain a consistent pattern and stagger the joints between each course of shingles.
Tips & Warnings
- Use caution when working on a rooftop. Wear a harness to avoid falling and injury.
- Photo Credit roof image by Andrey Rakhmatullin from Fotolia.com
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