Model "W10" Soffit Vent
Soffit Ventilation Calculator
(Soffit "W3" Calculator, Soffit "W6" Calculator)
Based on the 1/150 or 1/300 Rule
To determine how many Model "W10" soffit vents of a given length (inches) are required to properly ventilate an attic space:

soffit vents, Model D
SV-W10-L10
Material Width=10"
Overall Length=10"
Free Air Space=40 sq. in.
SV-W10-L18
Material Width=10"
Overall Length=17.5"
Free Air Space=80 sq. in.
SV-W10-L24
Material Width=10"
Overall Length=23.5"
Free Air Space=120 sq. in.
If you know the length &
width of the attic floor:
OR
If you know the square footage of the attic floor:

1. Enter the length of
the building in feet
2. Enter the width of
the building in feet
3. Choose the desired vent


4.

vents required - 1/300 rule

5.

vents required - 1/150 rule

1.Enter the total area of attic
in square feet



2.Choose the desired vent


3.

vents required - 1/300 rule

4.

vents required - 1/150 rule

Application: One vent for intake per:

Model
Sq. Feet
of Floor
1/150
Sq. Feet
of Floor
1/300
Net Free
Vent Area
in Sq. Inches
Net Free
Vent Area
in Sq. Feet
SV-W10-L10
84
168
40
0.28
SV-W10-L18
168
336
80
0.56
SV-W10-L24
249
498
120
0.83