Attic Ventilation Requirements Ibc

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.

Attic ventilation requirements ibc.

Designers may view unvented attic i e. 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. 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. 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.

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. 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. Openings for ventilation having a least dimension larger. Insulation requirements for roofs are therefore spread across ibc chapters 12 13 and 15.

The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. 21 5 and 387 lineal ft. An ice dam is a ridge of ice that forms at or. 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. The international building code ibc requires that ventilation be provided in all buildings. Mechanical ventilation is typically required in under floor areas bathrooms and some attic spaces. Building ventilation can be provided through natural or mechanical means.

The majority of the requirements related to attic ventilation have not changed much from the previous editions. 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. Another consequence and indication of improper attic ventilation is the formation of ice dams. 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.

The roofing industry also has practical guide lines for attic ventilation. 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 following are the requirements taken directly from the irc.