>
<area shape=
Venting Requirements
1994 UNIFORM BUILDING CODE

1505.3 Ventilation. Where determined necessary by the building official due to atmospheric or climatic conditions, enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain and snow. The net free ventilating area shall not be less than 1/150 of the area of the space ventilated.

Venting by Square Footage of the Building

Exceptions:

1. The area may be 1/300 of the area of the space ventilated provided 50 percent of the required ventilating area is provided by ventilators located in the upper portion of the space to be ventilated at least three feet above eave or cornice vents with the balance of the required ventilation provided by eave or cornice vents.

2. The area may be 1/300 of the area of the space ventilated provided a vapor retarder having a transmission rate not exceeding 1 perm is installed on the warm side of the attic insulation.

Application: One vent for exhaust per:

AV-4 52 Sq Feet of Floor
AV-6 100 "
AV-8 200 "
AV-10 327 "
AV-12 450 "
AV-14 600 "
AV-16 837 "
AV-18 1050 Sq Feet of Floor
AV-20 1308 "
AV-24 1883 "
AV-30 2941 "
AV-36 4237 "
AV-42 5766 "
AV-48 7533 "

Venting Requirements Calculator
To determine how many units of a given Aura Vent are required to properly ventilate a given area:

Enter the length of one side of house in feet
Enter the height of other side of house in feet
Choose the desired vent


vents required

TO DETERMINE THE VENTING REQUIREMENTS

The following formula makes it easy to calculate exactly how many of each type of vent you will need for a given application

.

STEP 1: Calculate your attic size in sq. ft.

STEP 2: 1/300 Rule: Step 1 x .24 = Total sq. inches of ventilation requirement for exhaust.

STEP 3: Step 2 ÷ Free area of vent chosen from data sheet = number of vents required.

buildings

buildings

EXAMPLE:

Home is: 30' W x 40' L
= 1,200 sq. ft.
x .24 = 288 Total sq. inches of ventilation required for exhaust

288 ÷ the sq. inch opening size of ventilator

288 ÷ 28 sq. inch opening of the AV6 = 10.28
Rounds to 10

EXAMPLE:

2. 1,200 x 2.4 = 288 sq. ft. in req.

3. 288 ÷
AV6
28 = 10 vents req.
AV8
50 = 6 vents req.
AV12
113 = 3 vents req.
AV14
144 = 2 vents req.
AV18
215 = 1 vent req.

TO DETERMINE THE SIZE AND QUANTITY OF POWERED VENTILATORS REQUIRED BASED UPON THE CUBIC FEET OF AN ATTIC OR BUILDING AND THE AMOUNT OF AIR CHANGES DESIRED
STEP ONE Measure the width of the building 72
STEP TWO Measure the length of the building 196
STEP THREE Divide the width of the building (step 1) in half 36
STEP FOUR Obtain the pitch of the roof 3 by 12
STEP FIVE Calculate the height per foot in feet. Divide 3" by 12" 0.25
STEP SIX Multiply half the width of the building (step 3) by height per foot (step 5) to obtain the height of the attic
9
STEP SEVEN To obtain the square area, multiply the height (step 6) by half the width (step 3)
324
STEP EIGHT To obtain the cubic feet of the attic, multiply the square area (step 7) by the length (step 2)
63,504
STEP NINE Determine the amount of air changes desired per hour 4
STEP TEN To obtain the cubic feet per hour air exhausted, multiply by the number of air changes wanted per hour (step 9) by the cubic feet of the attic (step 8)
254,016
STEP ELEVEN To calculate CFM, divide cubic feet per hour (step 10) by 60 4,233.6
STEP TWELVE Compare (step 11) with Aura Fan Ventilator to determine which unit or units will provide the CFM required
AV-8 AV-12 AV-14 AV-18 AV-24
CFM 200 700 1,000 2,200 4,000
CFM Needed 4,233.6 4,233.6 4,233.6 4,233.6 4,233.6
Units Needed 21.2 6.0 4.2 1.9 1.1
Rounded 21 6 4 2 1
STEP THIRTEEN Calculate the free air space in inches required for fresh air inlet according to UBC (step 1 x step 2 x .48)
6,774