Attic Ventilation Requirements Ibc

An ice dam is a ridge of ice that forms at or.

Attic ventilation requirements ibc.

Designers may view unvented attic i e. 21 5 and 387 lineal ft. 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.

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. 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. The majority of the requirements related to attic ventilation have not changed much from the previous editions. 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 ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. 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. Building ventilation can be provided through natural or mechanical means. 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.

Another consequence and indication of improper attic ventilation is the formation of ice dams. The international building code ibc requires that ventilation be provided in all buildings. 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. 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.

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. Mechanical ventilation is typically required in under floor areas bathrooms and some attic spaces. Insulation requirements for roofs are therefore spread across ibc chapters 12 13 and 15.

Now we can calculate the ventilation requirements using these products and our example building from before. 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.