How many CFM should my bathroom fan be?

For medium-sized bathrooms, use 80 to 99 CFM bath fans. For large bathrooms that are over 100 square feet but under 150 square feet, use over 100 CFM bath fans. For extra-large bathrooms, add 50 CFM for every toilet, 50 CFM for every bathtub or shower and 100 CFM for a jetted bathtub.

Is 80 CFM enough for bathroom?

But O’Brian suggests a simpler rule of thumb: 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, if your bathroom is 80 square feet, you’ll need an 80 CFM fan, such as the Broan SmartSense 80 CFM Ventilation Fan (available from SupplyHouse).

Can a bathroom fan be too powerful?

A Bathroom fan should not be overpowered since this will waste energy, create excessive noise and could even pull noxious carbon monoxide into the home. It is OK to get a 20-30 % higher capacity exhaust fan than specified by the CFM calculator.

Is 110 CFM too much for small bathroom?

Bathroom vent fans are rated for the amount of air they can move, measured in cubic feet per minute, or CFM. Standard fan sizing applies to bathrooms that are 100 square feet or less. The rule of thumb is that you need at least 1 CFM per square foot of room area.

How many CFM do I need for a bedroom?

Divide the total BTU requirements for the room by 30 to obtain the necessary CFM requirements. You need 1 CFM for every 30 BTU in a room.

Can 2 bathroom fans share a vent?

Bathroom fans can share a common vent. Both fans must be of similar capacity and have back-draft dampers installed. The duct must be over-sized by one inch for every additional fan added to the system. So, you have two or more bathrooms and only one duct.

How do I make my bathroom fan stronger?

Vent under the floor to get outside. Mount the fan high on the wall to better capture warm, moist air. Fabricate the duct run from rigid metal or PVC material. And install a more powerful fan to overcome natural convection and exhaust the air down and out.

Should I oversize my bathroom fan?

First, it’s a good idea to oversize the fan slightly. In our sample 54-square-foot, for example, it’s a good idea to install a 60 CFM fan for good measure. Second, if your bathroom has a jetted tub or separate rooms or alcoves, you might want more than one fan.