Ibc Roof Ventilation Requirements

For help finding them see our quick roofing guide to the ibc.

Ibc roof ventilation requirements.

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. 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. 1202 4 under floor ventilation the space between the bottom of the floor joists and the earth under any building except spaces occupied by basements or cellars shall be provided with ventilation in accordance with section 1202 4 1 1202 4 2 or 1202 4 3. The primary roofing chapter in the irc is chapter 9 roof assemblies.

These spaces are formed where ceilings are applied directly to the underside of roof framing members. 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. Enclosed attic spaces for buildings that fall under the ibc are required to be ventilated. Most requirements for roofing and thermal efficiency in ibc are contained in chapter 13 energy efficiency or chapter 15 roof assemblies and rooftop structures however chapter 12 interior environment addresses among other topics ventilation and temperature control.

Ibc 1203 2 requires 1 150 th of the attic area to be ventilated but there is an exception that is commonly used instead. Theinternational 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. 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. Contributes to but does not supersede thermal resistance requirements for attic and roof assemblies in section c402 2 1 of the international energy conservation code.

The net free vent area nfva shall not be less than 1 150 of the area of the space being vented. 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. However many other parts of the code deal with aspects of roofing.