Vented attics shall have a minimum net free ventilation area at least 1 300 of the area of the vented space.
Roof ventilation irc 2015.
Ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum.
The majority of the requirements related to attic ventilation have not changed much from the previous editions.
Air vent provides a complete line of ventilation products that meet the highest standards for quality and performance.
The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.
International residential code 2015 irc 2015 part i administrative chapter 1 scope and administration part ii definitions chapter 2 definitions part iii building planning and construction.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
The following are the requirements taken directly from the irc.
Between half and two thirds of the provided ventilation shall be installed at the eaves.
This shortcut conveniently calculates the 2015 international residential building code minimum irc section r806 roof ventilation 1 which states in part 1 square foot of net free area for every 150 square feet of attic floor space with the attic defined as length x width floor of the attic.
2015 international residential code for attic ventilation air vent inc.
Unvented attics and unvented enclosed roof framing assemblies created by ceilings that are applied directly to the underside of the roof framing members and structural roof sheathing applied directly to the top of the roof framing members rafters shall be permitted where all the following conditions are met.
The ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum.
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.
