What Size Vent Fan For A Bathroom

For example if your bathroom is 80.

What size vent fan for a bathroom. Sizing for large bathrooms for bathrooms over 100 square feet exhaust fans can be sized according to the number of fixtures in the room. The formula to calculate bathroom exhaust fan size reads as follows. For bathrooms between 50 and 100 square feet estimate approximately 1 cfm per square foot.

Here s how we get this number. Any bathroom of any size should have a vent fan but the best fan for the job depends on the size of the room. In general for rooms with 8 foot ceilings.

For bathrooms less than 100 square feet you can just go with 1 cfm for every square foot of floor area he says. For example a 10 wide by 15 long bathroom with a 10 ceiling would need. 1500 60 25.

The minimum allowed fan size is 50 cfm so if your bathroom is for example only 42 square feet you still need a 50 cfm fan. Cubic volume 7 5 cfm necessary. The fan model its size and cfm rating or the required or design flow rate in cfm from your local code such as 60 or 80 cfm.

Some also provide added conveniences such as timers overhead lighting moisture sensors and even a heat feature. Industry experts recommend 60 cfm to 80 cfm for small bathrooms and 200 to 300 cfm for a large bathroom with a steam generator. A 3 or 4 inch duct connects to the outlet on the fan housing and runs to a side wall or to the roof and connects to a vent cap that allows the exhaust to disperse outdoors.

But o brian suggests a simpler rule of thumb. If your bathroom is larger than 100 square feet tally the cfm requirements for the individual fixtures to estimate your needs. If your bathroom has a higher ceiling multiply the width x length x height of the room divide by 60 minutes in an hour then multiply by 8 number of air exchanges per hour.