Attic Ventilation Requirements Ibc

The international building code ibc requires that ventilation be provided in all buildings.

Attic ventilation requirements ibc. 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. Designers may view unvented attic i e. Now we can calculate the ventilation requirements using these products and our example building from before. Building ventilation can be provided through natural or mechanical means.

Exterior openings into the attic space of any building intended for human occupancy shall be protected to prevent the entry of birds squirrels rodents snakes and other similar creatures. Openings for ventilation having a least dimension larger. Another consequence and indication of improper attic ventilation is the formation of ice dams. The following are the requirements taken directly from the irc.

Ice dams may be a result of a poorly designed roof a defective attic ventilation system inadequate insulation levels improperly installed insulation or air leaks through the ceiling plane. Requirements applicable to attic ventilation. Attic space enclosed rafter or joist space above normally occupied and conditioned interior space assemblies as an economical arrangement of roofing and insulation materials. Mechanical ventilation is typically required in under floor areas bathrooms and some attic spaces.

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 international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process. An ice dam is a ridge of ice that forms at or. 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.

Openings for ventilation having a least dimension of not less than 1 16 inch 1 6 mm and not more than 1 4 inch 6 4 mm shall be permitted. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. Insulation requirements for roofs are therefore spread across ibc chapters 12 13 and 15. If we assume a ventilation strategy that involves a combination of dome roof vents and continuous soffit vents this building would need 22 15 diameter dome roof vents 3096 sq in.

The majority of the requirements related to attic ventilation have not changed much from the previous editions. 21 5 and 387 lineal ft. The roofing industry also has practical guide lines for attic ventilation.