N.Y.C. Admin. Code § EBC 814: Section EBC 814: Interior Environment

814.1 Ventilation requirements for enlarged bathrooms, toilet rooms, kitchens, and kitchenettes.

For bathrooms, toilet rooms, kitchens and kitchenettes undergoing enlargement, natural or mechanical ventilation sized in accordance with the New York City Mechanical Code shall be provided for the proposed floor area.

Exceptions:

1. Bathrooms and toilet rooms enlarged to meet the accessibility requirements of the New York City Building Code and that increase the room size by less than 50 percent of the existing floor area shall be permitted to maintain the existing means of ventilation without an increase provided no additional plumbing fixture is being proposed.

2. Kitchens and kitchenettes enlarged to meet the accessibility requirements of the New York City Building Code shall be permitted to maintain the existing means of ventilation without an increase in ventilation size provided no additional cooking appliance load is being proposed.