Bathroom exhaust fans need to remove and exchange air in the room every 3.5 minutes creating a healthy environment and maintaining paint, drywall, caulking, vanity, wood trim, medicine cabinet, metal fixtures. They also help to prevent lights free from premature mold, mildew or rust. The fan must be left on for at least 10 minutes (14 minutes is ideal for 4-time air exchange) minimum to exchange the air 3 times after showering or taking a bath. For those who need to leave bathroom worry free, we can add a timer as a switch.
(Failure to right size your bath fan may cause mold, mildew, deteriorated plumbing fixtures, peeling paint, falling drywall/framing or cabinetry and doors that are warped).
Bathroom exhaust fans noise rating is measured in Sones. A sone is a measure of loudness. The higher the sone rating the louder the sound.
Understanding how loud an exhaust fan will be can be difficult, largely because bathroom exhaust fans are measured in sones, while most common noise levels we are familiar with are measured in decibels.
Fan options are available with light, without light, night light, heater , moisture sensing switch, can light fan and flush mount decorative light fixture.
It is recommended (now mandatory building code) and our company policy to make sure all bathroom exhaust fans exit thru the roof or eave with insulated vent piping. If you do not insulate the attic exhaust piping hot and cold air will mix and cause moisture which will mold and mildew in the duct work.
The chart below will help with choosing the proper zone rating for your bathroom exhaust fan:
1.0 a quiet refrigerator
2.0 quiet home
3.0 normal office
4.0 normal television volume
How to size your bathroom fan for proper air exchange:
Fans needed 90 CFM (Cubic Feet per Minute) without a light 5×8 bathroom or 320 cubic feet.
90 CFM with light
110 CFM without light 6×8 bathroom or 384 cubic feet
110 CFM with light
140 CFM without light 8×9 or 576 cubic feet total
140 CFM with light