Attic Ventilation Required

Choose one of the following products to meet the recommended intake nfva of 528 square inches.

Attic ventilation required.

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. In of vent opening per 150 sq. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. 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.

Then aim for about 1 sq. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Foot of ventilation for every 150 sq. Allows cool dry air to enter the attic.

You can also contact your local municipality to check on building code in your area. Feet of attic space divided 50 50 between the inlets and outlets. 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. Ft of attic space for example 20 x 50 to be effective.

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. The majority of the requirements related to attic ventilation have not changed much from the previous editions. Intake vents located at the lowest part of the roof under the eaves allow cool. The following are the requirements taken directly from the irc.

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. Ventsure inflow intake vent. Attic for example has an area of 1 200 sq. A 30 x 40 ft.

First determine your attic area by multiplying the length by the width. Vents are rated by their net free area or the amount of space for air to flow in or out. Lines for attic ventilation. How many vents do you need.

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. 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.