Residential Roof Ventilation Requirements

2015 international residential code for attic ventilation the code minimum ratio is 1 150.

Residential roof ventilation requirements. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Based on your 1100 sq. If your attic is enclosed california s building code states it should have cross ventilation. R806 1 ventilation required 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 or snow.

Chapter 8 roof ceiling construction. 2018 international residential code. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. Pdf2015 international residential code for attic ventilation 145 kb.

Government codes utility programs and private energy programs often cite national standards as part of their requirements. Ventilation standards are consensus documents published by professional or technical groups showing good practice. Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed. And this guideline you ll need a minimum of.

Always have a balanced ventilation system. Blocking and bridging must be arranged so they do not interfere with air movement. The net free vent area nfva shall not be less than 1 150 of the area of the space being vented. Ventilation openings having a least dimension larger than 1 4 inch 6 4 mm shall be provided with corrosion resistant wire cloth screening hardware cloth perforated vinyl or similar material with openings having a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum.

As an example of what you can find in chapter 8 of the 2018 irc see. Near ridge of the roof. 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. Ansi ashrae standard 62 2 is the national consensus standard on residential ventilation in the united states.

Contains sections covering roof framing roof sheathing and roof ventilation. 2018 international residential code. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation. Air space no less than 1 inch must be provided between any insulation or obstruction and the roof sheathing.