How to calculate bathroom exhaust fan CFM#
Building code requires minimum 1 CFM of exhaust capacity per square foot of bathroom area (e.g. minimum 50 CFM for a 50 ft² room). For larger primary bathrooms with jetted tubs or steam showers, add 50 CFM per standard shower/tub and 100 CFM for steam fixtures.
Electrical safety wet zones and GFCI protection#
- GFCI protection: All outlets within 5 feet of water sources must be GFCI-protected.
- Shower lighting: Light fixtures installed directly inside wet shower zones must be rated "Suitable for Wet Locations" with sealed gasket lenses.
- Floor heat sensor placement: Always install a backup temperature sensor wire in the mortar bed before tiling over radiant heating cables.