Exterior Vent Terminations & Wall and Roof Caps
The cap where a vent exits the building is where most venting problems start. I install wall and roof caps with proper backdraft dampers, sealed and flashed to keep weather and pests out.
What I do
- Install wall caps and roof caps for bath, range hood, and dryer vents
- Fit backdraft dampers so air goes out but not back in
- Seal and flash terminations against wind-driven rain
- Add pest screening that does not choke airflow
- Replace failed, painted-over, or missing exterior caps
Common problems I fix
- Caps with stuck or missing dampers that let cold air and pests back in
- Builder-grade plastic caps that crack and leak in Sea to Sky weather
- Terminations buried behind siding with no real opening
- Multiple vents dumped into one undersized cap
Good-fit projects
- New exterior finishes or re-siding
- Correcting a vent that leaks air or water
- Replacing a cracked or painted-shut cap
- Coordinating cap locations during a renovation
Most venting problems I get called for are not in the duct. They are at the cap where the duct leaves the building. A termination that is cracked, missing its damper, or never sealed properly lets cold air, rain, and pests back in and quietly undoes the rest of the run.
What a good termination does
A proper exterior cap does three things at once: it lets exhaust out on demand, it closes against backflow with a working damper, and it stays sealed and flashed so wind-driven rain cannot track in behind the siding or under the shingles. In a wet, windy corridor like the Sea to Sky, the flimsy builder-grade plastic caps are usually the first thing to fail.
Backdraft dampers and pest screening
A damper is what keeps a vent from becoming a hole in the wall when the fan is off. I fit dampers that actually seat closed, and add pest screening sized so it keeps rodents and birds out without choking the airflow: fine mesh on a range hood, for example, clogs with grease and kills the pull.
The right time to get caps right
The best moment is when the exterior finish is open or being replaced. New siding, a new roof, or a renovation is the chance to place caps where the duct runs actually want to exit, seal them into the assembly, and avoid the patched-in look of a cap added after the fact.
Where I provide this service
I serve Squamish, Whistler, Pemberton, and nearby Sea to Sky communities. See service areas.
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Frequently Asked Questions
Why does the exterior vent cap matter so much?
The cap is where the duct meets the weather. A good one lets air out, keeps wind-driven rain, cold air, and pests from coming back in, and stays sealed to the wall or roof. A cracked or damper-less cap undoes an otherwise clean duct run.
Can a bathroom fan and a dryer share one exterior cap?
No. Each exhaust should have its own correctly sized termination. Sharing a cap chokes airflow and lets one appliance push air or lint back into another. I give each vent its own properly sized, dampered exterior cap.