1203.5.1.2.1 Minimum opening.
BC § 1203.5.1.2.1
The minimum openable area to the outdoors shall be 5 percent of the floor area of the habitable space being ventilated. Every opening providing required natural ventilation shall be at least 12 square feet (1.1 m 2 ) of glazed area, providing a minimum of 6 square feet (0.56 m 2 ) of openable area. Exceptions: 1. Where fresh air is furnished in any habitable room or space by mechanical means supplying a minimum of 40 cubic feet per minute (0.02 m 3 /s), the free openable area of the openings may be reduced to 2 1/2 percent of the floor area but each such opening shall provide not less than 5 1/2 square feet (0.51 m 2 ) of openable area.
2.The minimum free openable area of a mullioned casement window shall be 5 1/2 square feet (0.51 m 2 ), provided that the minimum ratio of floor area to openable area is met.
