What Is a Good Seal for Sealing a Roof Vent?

Proper Flange

• The flange is the section of the vent that extends out over the roof, both underneath and on top of the shingles or other materials that you are using for your roof covering. Flanges are a vital part of proper sealing and should always provide an even and uncracked surfaced for the vent top to rest on. Rubber flanges can be added for more sealant protection, and flanges can be extended to help deal with awkwardly shaped roofs.

Roofing Tar

• Roofing tar is the common roofing adhesive used to attach asphalt shingles. It is the first step in leak defense when patching around a roof vent. The tar is placed below the flange for the shingles that will go beneath it, and then on the flange for the layers of shingles that will go over the top of the flange. Lastly, roofing tar should be daubed on the edges of the shingles cut around the flange before the final layer of shingles is added.

Roof Caulks and Cements

• Roof caulks and cements provide an additional layer of protection for rooftops where you are replacing the roof vents. These caulks and cements are used on top of the shingles, against the metal of the vent itself. They are also used for any vent attachments that run above the shingles and may provide another entry point for rain. These are waterproof caulks and mortars designed specifically for roofing applications, so shop carefully when buying.

Sealant Coatings

• Sealant coatings are thin layers of sealer that are used to coat vent work and provide a final layer of protection against water. They form thin, invisible coatings on the nails and screws you use to install the vents. This helps fill in any cracks that are too small to be noticeable and can still provide ingress for dripping moisture.