User Guide

4
Ventilation for baths over 100 square feet is calculated based on the fixtures in the bathroom
(see table below). Add the CFM of all fixtures within the bathroom for the required fan CFM.
Enclosed toilet rooms must have an operable window or a fan for ventilation.
1. Install a 100 CFM fan over the tub, 50 CFM fan in the shower and above the toliet. This method will
provide ventilation where and when it’s needed.
2. Install one 150 CFM fan. The air will be pulled through the entire room and exhausted at a central
location.
Based on the Home Ventilating Institute (HVI) guidelines
FAN SIZING FOR BATHROOMS UNDER 100 SQUARE
FEET
The standard rule for bathrooms 100
square feet or smaller is one CFM per
square foot of the bathroom. To find the
square footage, multiply the length of the
bathroom by the width.
9’
5’
45 sq.ft.
The minimum recommendation is
a fan rated at least 45 CFM.
For more information on bath fan sizing and ventilation, visit www.hvi.org.
Bathroom Fan Sizing
Toilet 50 CFM
Shower 50 CFM
Bath Tub 50 CFM
Jetted Tub 100 CFM
CFM REQUIRED PER FIXTURE
1 Toilet 50 CFM
1 Jetted Tub 100 CFM
Required CFM 150 CFM
EXAMPLE
SOLUTION