Vent Pipe Flashing

Definition: Vent pipe flashing is a roofing system used to seal around vent pipes that come through the roof. It impedes the flow of water, debris, and insects from the roof through the openings made by these pipes. Vent pipe flashing helps to ensure the waterproofing of the roof, particularly when plumbing, HVAC or exhaust pipes poke their way through the roof.

Key Features:

• Floodproof Seal: Vent pipe flashing seals pipes and prevents water entry to the roof deck or attic.
• Polymer Fabric: Most vent pipe flashings allow slight pipe motion due to temperature fluctuations or construction movement.
• Robust Construction: Flashings are manufactured from material that is resistant to weathering, UV radiation and temperature.

Types of Vent Pipe Flashing:

• Rubber Boot Flashing: This type is made from malleable rubber or silicone, and it is widely utilized because of the tight seal around the pipe.
• Metal Flashing with Rubber Collar: It combines the rigidity of metal (aluminum or galvanized steel) with the malleability of a rubber or silicone collar to create a waterproof seal.
• Lead Flashing: Common in classic or architectural applications, lead flashing is long-lasting and fits readily around pipes although it can eventually need to be sealed more.
• Multi-Flue Flashing: Used to flash multiple pipes or vents in a close vicinity in an industrial or commercial environment.

Learn more: What is Kickout Flashing?

Installation Process:

• Installation of Flashing: The flashing is rolled over the pipe and placed on the roof deck so that the flange sits flat on the roof.
• Securing: The flange is screwed or nailed to the roof deck, which ensures that it is held securely without damaging the roof.
• Sealing: Roof sealant is used around the flashing edge to prevent water leakage and ensure the seal is tight.
• Roofing Material Overlap: The roof material (shingle, for example) is laid to overlap the top of the flashing flange, so water flows over and away from the pipe.

Common Issues:

• Broken Rubber Boots: Over time, rubber parts can break and lose the seal from the UV radiation or high temperatures.
• Loose Flashing: A bad installation or strong winds will cause the flashing to become loose and leak.
• Roughness (Metal Flashing): Metal flashing can rust or corrode if they are not properly cleaned or cared for.

Benefits:

• Keeps Leaks From the Roof: Vent pipe flashing prevents water from invading the roof deck and attic by securing the pipes around them.
• Improves Roof Life: Properly installed flashing increases the life of the roof by avoiding moisture leakage.
• Flexible Products: Available in a variety of sizes and types to suit different pipe diameters and roofing.