Attic Ventilation Required

According to the home ventilating institute hvi powered attic ventilators need to move a minimum of 700 cubic feet per minute cfm for 1 000 sq.

Attic ventilation required.

In of vent opening per 150 sq. The net free vent area nfva shall not be less than 1 150 of the area of the space being vented. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. First determine your attic area by multiplying the length by the width.

Lines for attic ventilation. Then aim for about 1 sq. Foot of ventilation for every 150 sq. Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge.

The following product options will allow you to achieve an intake nfva of 528 square inches. Allows cool dry air to enter the attic. Choose one of the following products to meet the recommended intake nfva of 528 square inches. You can calculate attic ventilation requirements by determining the square footage of your attic floor its width times its length and compare that to the total required net free area nfa.

Attic for example has an area of 1 200 sq. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. The majority of the requirements related to attic ventilation have not changed much from the previous editions. Vents are rated by their net free area or the amount of space for air to flow in or out.

The following are the requirements taken directly from the irc. Attic ventilation requirements how many attic vents your roof needs industry standard for proper attic ventilation recommends for no vapor retarder type of attic insulation no paper plastic or aluminum layer between the attic floor and insulation layer 1 sq. Intake vents located at the lowest part of the roof under the eaves allow cool. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.

Code requirements the international building code 2012 edition ibc 2012 requires enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing to have cross ventilation for each separate space. Ft of attic space for example 20 x 50 to be effective. You can also contact your local municipality to check on building code in your area. Most building codes require a ratio of 1 150 ventilation space to attic floor space.

Ventsure inflow intake vent. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.