To determine the required CFM (cubic feet per minute) for an 8x10 bathroom, you'll need to consider the volume of the room and the recommended air exchange rate. The recommended air exchange rate for bathrooms is typically 8 times per hour, meaning the air inside the bathroom should be completely replaced with fresh air 8 times in an hour.
First, calculate the volume of the bathroom:
Volume = Length × Width × Height Volume = 8 ft × 10 ft × standard ceiling height (assume 8 ft for this example)
Volume = 640 cubic feet
Next, calculate the required CFM:
Required CFM = (Volume × Air Exchange Rate) / 60
Required CFM = (640 ft³ × 8) / 60
Required CFM = 85.33
Therefore, you would need a bathroom exhaust fan with a minimum CFM rating of approximately 85.33 CFM to achieve 8 air changes per hour in an 8x10 bathroom with standard ceiling height.
It's worth noting that for bathrooms with special features such as a steam shower or jetted tub, you might need to increase the CFM rating accordingly to adequately remove excess moisture and maintain good ventilation. Additionally, it's always a good idea to choose a bathroom fan with a slightly higher CFM rating than the calculated minimum to ensure optimal performance and efficiency.