Section 423.5 is hereby added to the International Building Code and shall read as follows:

423.5 Storm protection area required. All Group R-1, R-2, R-3, R-4, I-1 and I-2 occupancies of any occupant load shall have a storm protection area constructed in accordance with ICC 500 or shall have a basement. Sub-surface areas located beneath concrete stoops with or without doors are considered equivalent to a basement. Such areas shall be provided with ventilation in accordance with applicable code requirements.

Exception: Storm shelters are not required for existing buildings or for repairs, alterations or additions for existing buildings when the area of work is less than 50% of the building area.

423.5.1 Required occupant capacity. The required occupant capacity of the storm protection area in all Group R and I occupancies shall be calculated as private dwellings per Table 403.3.1.1 of the International Mechanical Code as adopted and amended. Where approved by the building official, the required occupant capacity of the storm protection area shall be permitted to be reduced by the occupant capacity of any existing storm protection area on the site.