Proper Attic Ventilation Requirements

Your roof vents may not look.

Proper attic ventilation requirements.

This is accomplished through the placement of ventilation near the bottom of the attic space at the soffits or eaves intake and at the top peak s or ridge s of your attic space exhaust. Measure the length and width of the attic floor space to be ventilated. If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. Regarding attic ventilation nrca recommends designers provide at least 1 square foot of nfva for every 150 square feet of attic space 1 150 ventilation ratio measured at the attic floor level ceiling.

The ventilation ratios go according to attic floor size not roof size. If you don t see any attic vents on the roof or in the eaves you need to add some. Once they are in place you can then place the batts or blankets or blow insulation right out to the very edge of the attic floor. Of vent for every 300 sq.

The following are the requirements taken directly from the irc. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. Look at your eaves and roof. You can also contact your local municipality to check on building code in your area.

In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. You can go as low as 1 300 of the attic floor area for attics which have a continuous vapor barrier below to a high of 1 5 in inches x the floor area in feet.

A hot ceiling tells you that the attic is acting like a solar oven raising your cooling bills and. There should also be a 50 50 balance of attic venting and roof venting. Touch your ceiling on a warm sunny day. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space.

The majority of the requirements related to attic ventilation have not changed much from the previous editions.