TECHNICAL INFORMATION

Certifications
Specifications
Architectural Drawings
Net Free Area Charts

 


NET FREE AREA CHARTS:
1:150 Ratio-no Moisture Barrier     1:300 Ratio-w/ Moisture Barrier

1:150 ratio: Net Free Area Table-Use when no Moisture Barrier is installed.
The MINIMUM attic ventilation required by the Building Codes is 1 square foot of total net free area per 150 square feet of attic when no moisture barrier is used.
A Balanced System requires soffit ventilation in an amount equal to or greater than the amount of ridge ventilation.  See soffit vent manufacturer's information on the Net Free Area provided by soffit vent product.

Attic
Area
(SF)
Minimum
NFA
(SF)
Exhaust
NFA (SF)

Length of
Roof Saver
(FT)

Intake
NFA (SF)

1000
6.67
3.33
31.6
3.33
1100
7.33
3.67
34.7
3.67
1200
8.00
4.00
37.9
4.00
1300
8.67
4.33
41.1
4.33
1400
9.33
4.67
44.2
4.67
1500
10.00
5.00
47.4
5.00
1600
10.67
5.33
50.5
5.33
1700
11.33
5.67
53.7
5.67
1800
12.00
6.00
56.8
6.00
1900
12.67
6.33
60.0
6.33
2000
13.33
6.67
63.2
6.67
2100
14.00
7.00
66.3
7.00
2200
14.67
7.33
69.5
7.33
2300
15.33
7.67
72.6
7.67
2400
16.00
8.00
75.8
8.00
2500
16.67
8.33
39.5
8.33
2600
17.33
8.67
41.1
8.67
2700
18.00
9.00
42.6
9.00
2800
18.67
9.33
44.2
9.33
2900
19.33
9.67
45.8
9.67
3000
20.00
10.00
47.4
10.00
See soffit vent manufacturers instructions for NFA calculation.


1:300 ratio: Net Free Area Table-Use when Moisture Barrier is installed
The MINIMUM attic ventilation required by the Building Codes is 1 square foot of total net free area per 300 square feet of attic when a moisture barrier is installed.
A Balanced System requires soffit ventilation in an amount equal to or greater than the amount of ridge ventilation. See soffit vent manufacturer's information on the Net Free Area provided by soffit vent product.

Attic
Area
(SF)
Total NFA
(SF)
Ridge Ventilation
NFA (SF)
Length of
Roof Saver
(FT)
Sofit Ventilation
NFA (SF)
1000
3.33
1.67
15.8
1.67
1100
3.67
1.83
17.4
1.83
1200
4.00
2.00
18.9
2.00
1300
4.33
2.17
20.5
2.17
1400
4.67
2.33
22.1
2.33
1500
5.00
2.50
23.7
2.50
1600
5.33
2.67
25.3
2.67
1700
5.67
2.83
26.8
2.83
1800
6.00
3.00
28.4
3.00
1900
6.33
3.17
30.0
3.17
2000
6.67
3.33
31.6
3.33
2100
7.00
3.50
33.2
3.50
2200
7.33
3.67
34.7
3.67
2300
7.67
3.83
36.3
3.83
2400
8.00
4.00
37.9
4.00
2500
8.33
4.17
39.5
4.17
2600
8.67
4.33
41.1
4.33
2700
9.00
4.50
42.6
4.50
2800
9.33
4.67
44.2
4.67
2900
9.67
4.83
45.8
4.83
3000
10.00
5.00
47.4
5.00
See soffit vent manufacturers instructions for NFA calculation.