Bathroom exhaust fan making loud noise — Oakland, California

A bathroom exhaust fan that grinds, rattles, or hums loudly has usually reached the end of its motor bearings' life — most bath fans last 8–12 years before the motor wears out. Beyond being annoying, a failing fan no longer moves enough air to prevent moisture buildup, which leads to mold on grout, peeling paint, and even rotted ceiling joists. Replacing a bath fan is an electrical job: it involves disconnecting the old unit from its junction box, possibly resizing the ceiling opening, and wiring the new fan — which may require running a dedicated circuit if you're upgrading to a higher-CFM model with a heater or humidity sensor. A licensed electrician can swap a standard fan in 1–2 hours ($150–$350 for labor plus $50–$200 for the fan). If the ductwork is disconnected or venting into the attic (a code violation that causes attic mold), expect an additional $100–$300 to route the duct properly through the roof or soffit.