When installed in accordance with manufacturer's recommendations, Air Vent products comply with the net free area requirements of nationally recognized model codes, including those written by BOCA, SBCCI and ICBO.

 

Here's an overview of the specifications for Air Vent's complete line of intake ridge ventilation products.

Product	Model	Description	Colors	Size	Net Free Area
The Edge™ Vent	EVI	Shingle-over, roof-top installed intake vent	Black	11.4" x 48"	9 sq. in. per ft.
Continuous Soffit Vent	SV201	Aluminum Continuous soffit vent (Retrofit)	White, Mill, Brown	2-3/4" x 96"	9 sq. in. per ft.
	SV202	Aluminum Continuous soffit vent (New Construction)	White	2-3/4" x 96"	9 sq. in. per ft.
	SV351	PVC Continuous soffit vent (Retrofit)	White	2-3/4" x 96"	9 sq. in. per ft.
Undereave Vents	EV16424	Aluminum	White, Mill, Brown	4" x 16"	28" pc
	EV16624	Aluminum	White, Mill, Brown	6" x 16"	42" pc
	EV16824	Aluminum	White, Mill, Brown	8" x 16"	56" pc
Vented Drip Edge	VDE	Aluminum	White	10'	9 sq. in. per ft.
2" Mini Louvers	MLM2MF	Tooled aluminum; die-stamped grill	Mill	2"	0.47/pc.
3" Mini Louvers	MLM3MF	Tooled aluminum; die-stamped grill	Mill	3"	1.34/pc.
4" Mini Louvers	MLM4MF	Tooled aluminum; die-stamped grill	Mill	4"	2.88/pc.

 

 

THE SIMPLE MATHEMATICS OF A BALANCED RIDGE VENTILATION SYSTEM

• According to most building codes, you need 1 square foot of ventilation for every 150 square feet of attic floor space.
• For new home construction that includes a vapor retarder, the minimum is 1 square foot of ventilation for every 300 square feet of attic floor space.
• If your vents are split between ridge vents and intake vents, the minimum requirement is also 1 square foot of ventilation for every 300 square feet of attic floor space.

To determine how many feet of net free area you need, use this formula:

Square feet of attic floor space 300	=	Square feet of net free area needed
For example:
1500 square feet of attic floor space 300	=	5 square feet of free area needed

 

Ridge Vent/Intake Vent Calculator for Standard Gable Attic

To use this calculator, first find the total square footage of the attic floor area. Round your calculations up to the next highest number (see Ventilations Requirements).

Then look across to the number under the Minimum Length of Ridge column. That tells you the total linear feet of ridge vent required using the 1/300 minimum code requirements. Note: because today's tighter homes require more airflow, the 1/150 ratio is also included.

To balance your ridge vent system, find the length of the ridge and follow the column to the right for required intake vents (see Balancing Your Ridge Vent System).

 

Ventilation Requirements

Attic Square Footage	Minimum Length of Ridge
	at 1/300 ratio	At 1/150 ratio
1200	16	32
1500	20	40
1800	24	48
2100	28	56
2400	32	64
2600	36	72
3000	40	80
3300	44	88

Note: Calculations are based on ShingleVent II and Multi-Pitch FilterVent which provide 18" of net free area per linear foot.

 

Balancing Your Ridge Vent System

Length of Ridge	Linear Feet of The Edge™ Vent shingle-over intake	Number of Undereave Vents
		16" x 8"	16" x 6"	16" x 4"
15'	30	5	6	10
20'	40	6	9	13
30'	60	10	13	19
40'	80	13	17	26
50'	100	16	21	32
60'	120	19	26	39
70'	140	23	30	45
80'	160	26	34	51
90'	180	29	39	58