1203.4.2 Exceptions.
BC § 1203.4.2
The following are exceptions to Sections 1203.4 and 1203.4.1: 1. Where warranted by climatic conditions, ventilation openings to the outdoors are not required if ventilation openings to the interior are provided.
2.The total area of ventilation openings is permitted to be reduced to 1/1,500 of the under-floor area where the ground surface is covered with a Class I vapor retarder material and the required openings are placed so as to provide cross ventilation of the space. The installation of operable louvers, in accordance with Section 1203.4.1, shall not be prohibited.
3.Ventilation openings are not required where continuously operated mechanical ventilation is provided at a rate of 1.0 cubic foot per minute (cfm) for each 50 square feet (1.02 L/s for each 10 m 2 ) of crawl space floor area and the ground surface is covered with a Class I vapor retarder.
4.Ventilation openings are not required where the ground surface is covered with a Class I vapor retarder, the perimeter walls are insulated and the space is conditioned in accordance with the New York City Energy Conservation Code.
5.Openings for under-floor ventilation for buildings in flood hazard areas shall also comply with the additional requirements of Appendix G.
