My bathroom fan isn't getting rid of the moisture after a shower. What's wrong?

Your bathroom fan likely isn't moving enough air to handle the moisture load, or it's not running long enough. Most bathroom ventilation problems come down to inadequate airflow, blocked ducts, or poor installation rather than a completely failed fan.

Start by checking the fan's airflow strength. Hold a tissue up to the grille while the fan runs — it should pull the tissue firmly against the opening. If there's barely any suction, you've found your problem. Many older fans lose effectiveness as dust builds up on the blades and housing, or the motor weakens over time.

Duct blockages are extremely common in New Brunswick homes, especially those built in the 1970s-1990s. The flexible duct running from your fan to the exterior may have sagged, creating low spots where condensation pools and lint accumulates. In our freeze-thaw climate, exterior vents can also ice up during winter, completely blocking airflow. Check that your exterior vent hood opens properly and isn't clogged with debris or ice.

The fan capacity might simply be too small for your bathroom. The National Building Code of Canada 2020 (which New Brunswick adopts, effective May 1, 2025 for new applications) requires bathroom fans to move at least 50 CFM (cubic feet per minute). Larger bathrooms need proportionally more — calculate roughly 1 CFM per square foot of floor area. Many builder-grade fans installed in the 1980s-2000s only move 30-40 CFM, which isn't adequate for today's tighter, more humid homes.

Runtime matters significantly. Your fan should run during the shower and for 15-30 minutes afterward to clear residual moisture. Consider upgrading to a fan with a built-in timer or humidity sensor that automatically runs until moisture levels drop. These smart controls typically add $50-150 to the project cost but prevent the mold and mildew issues that plague many New Brunswick bathrooms.

For a DIY assessment, clean the fan grille and housing thoroughly, check that the exterior vent opens freely, and verify the ductwork isn't sagging or disconnected in the attic space. However, if you need to replace the fan or run new ductwork, electrical work must be done by a licensed electrical contractor in New Brunswick — contact NB Power at 1-800-615-0522 for the required wiring permit, and Technical Inspection Services will handle the final inspection.

Expect $300-800 for a quality replacement fan installed, or $150-400 if you're handy enough to swap the unit yourself while leaving electrical connections to a licensed professional.