How to Install Flashing for House Wrap Penetrations

Water is the ultimate enemy of your home's structural integrity, and the points where pipes, vents, or electrical conduits pierce the exterior are its favorite entryways. Most leaks don't happen because of a failed product; they happen because water was allowed to track behind the weather-resistive barrier instead of flowing over it. Achieving a watertight seal requires thinking like a raindrop. A properly flashed penetration forces gravity to work for you, not against you. By layering your materials in a specific shingled order, you ensure that every drop of water that hits your wall is diverted away from the framing and safely down the face of the house wrap.

1. Cut and Secure the Opening. Cut the house wrap in a cross pattern (an X) at the location of the penetration. Fold the flaps inward and staple them securely to the interior framing to provide a clean surface for your flashing materials.
2. Seal the Bottom First. Apply a strip of self-adhered flashing tape to the bottom sill of the opening. Extend the tape at least two inches onto the exterior face of the house wrap.
3. Insert and Caulk Tight. Install your pipe, vent, or conduit through the opening. Seal the gap between the object and the wall with a high-quality exterior-grade sealant before moving to the next layer of flashing.
4. Build the Side Walls. Apply vertical strips of flashing tape to the left and right sides of the penetration. Ensure the tape covers the seam where the house wrap meets the penetration and overlaps the bottom sill tape.
5. Crown It with Overlap. Place the final strip of flashing tape across the top of the penetration. This piece must tuck under the existing house wrap above the hole so that water runs over the flashing, not behind it.
6. Complete the Weather Seal. Pull the top flap of the house wrap down over the top flashing piece. Secure all seams with seam tape to create a continuous weather-resistive surface.