Sealing Outside Wall Penetration?

To properly seal a round exterior penetration in a wall-mounted building (WRB), remove existing cladding and trim, prepare the wall sheathing for the air/water control membrane, and install a continuous air/water control membrane with a hole for the vent or pipe. Apply a bead of sealant around the duct/pipe penetration.

Piping that penetrates through walls can expose processing facilities to dust and dirt. Proper sealing of building penetrations can help reduce utility bills, prevent drafts, and stop moisture infiltration. Putties, sealants, and caulks are available for sealing electrical ducts and other processes.

Water barriers must be carefully sealed and flashed at all exterior wall openings and penetrations, including windows, doors, water spigots, exhaust vent outlets, HVAC condensate lines, light fixtures, and receptacles. Sealing inside of conduit is essential to stop condensation, and the best practice is to use a liquid-applied sealant that can seal out water and air in one application.

Outdoor rated caulk can be used on the outside, while spray foam can be used on the inside. Premade silicone boots can also be used for wall penetrations. Sealing around the outside of the conduit is typically done by making the hole larger than the pipe and grouting.

Canned expanding foam or a quality sealant can be used for sealing the penetration, and it is important to ensure all wires are fastened. If possible, remove enough external cladding to access and fully seal the wall underlay around the penetration.