Why does my bathroom mirror still fog up when the exhaust fan is running?
An exhaust fan can pass basic airflow tests while still being entirely underpowered for the volume of steam produced by a hot shower. This leaves the mirror fogged, causes water to drip heavily from the ceiling and walls, and creates lingering humidity that risks causing lasting damage to the room.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Buying a higher CFM exhaust fan
- 2Installing a timer switch
- 3Checking duct size, static pressure, and duct runs
- 4Leaving the bathroom door open to increase airflow
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Trying to find the best bathroom exhaust fan for a small bathroom because mine technically works, but a hot shower still turns the mirror and half the room into a cloud.”source ↗
“It passes the basic toilet paper test and is definitely pulling some air, but apparently that doesn't necessarily mean the bathroom ventilation is actually keeping up with the amount of steam coming from the shower head.”source ↗
“It introduced severe humidity issues. The fan drips, the ceiling drips, the walls have long drip lines than can run to the floor, the mirror stays foggy for so long and we are afraid it's caused damage to our bathroom.”source ↗
Where this came up
People with this problem also raised
- 2Why is my bathroom exhaust fan making a strange noise?
- 3How to clear heavy bathroom steam without an exhaust fan
- 3Why does my bathroom stay humid even with the fan on?
- 2How to clean a bathroom mirror without ruining the coating
- 2AC unit humming with no air coming out of vents
- 3How to stop inhaling harsh cleaning chemical sprays and mist