My contractor said my vent fan was too small. He was right.

Had a 5x5 bathroom. Bought a 50 CFM fan off Amazon. Thought it was fine. Guy came in for the tile work. Said I needed at least 80 CFM for that space. Laughed at me actually. Told me to check the math. He was dead on. Steam just hung there after showers. Mold started on the ceiling paint within 3 months. Swapped it out for a Panasonic 110 CFM. Night and day difference. Anyone else get bad advice from a big box store clerk?

3 comments

3 Comments

jessem598d agoMost Upvoted

@murray.robert, that whole "quality fan" thing is a myth I fell for hard. Had a 6x7 bath, bought a "commercial grade" 70 CFM from a supply house. Thought I was being smart. Used it for a year. Ceiling stayed damp. My buddy's son is an electrician, came over for a BBQ, looked at it and just shook his head. Said the motor was good but the duct run was a mess. Like 15 feet of flex duct with two bends. Choked the airflow. Swapped to rigid duct and bumped it up to 90 CFM. Now the mirror's clear in five minutes. Gut feel? Not when the paint's peeling.

murray.robert8d ago

Hanging steam and mold in 3 months sounds like it's more about the cheap fan and maybe the paint than the CFM rating itself. @david_reed22, I mean, I've seen bathrooms with undersized fans run fine for years if they're quality units and the bathroom gets aired out after showers.

david_reed228d ago

Did you actually measure the humidity in there before and after, or just going off gut feel?