Bathroom fan problems are usually duct problems, not fan problems

If a bathroom mirror stays fogged forever or paint keeps peeling over the shower, it is tempting to just buy a stronger fan. The annoying part is that the fan itself is often not the main issue.

Things I would check before calling a fan replacement “done”:

• Does the duct actually vent outdoors, not into the attic or a soffit cavity?
• Is the duct crushed, too small, disconnected, or full of lint?
• Is there a timer switch so the fan runs long enough after showers?
• Is the roof/wall cap flashed and damped correctly?
• Is replacement air getting into the bathroom under the door?

A quiet fan with a bad duct route is still a bad system. Also, stains around a fan can be roof leakage or duct condensation, not just shower steam, so repainting before diagnosing the source can be a waste.

Longer guide with cost ranges and questions to ask: https://sacvalleycontractors.com/blog/sacramento-bathroom-exhaust-fan-moisture-control-guide-2026/