1203.5.1.2.2 Adjoining spaces.
BC § 1203.5.1.2.2
An alcove or room opening off another room or space shall be considered as a separate room in determining its requirements for ventilation. Exceptions: 1. Alcoves within Group R-3 dwelling units. In Group R-3 occupancies, where an opening between the alcove and the room or space is at least 80 percent of the area of the common wall and the floor area of the alcove does not exceed twice the area of the opening, the alcove and the room opening into the alcove may be considered as a single space.
2.Balconies, partially enclosed. Exterior openings required for ventilation shall be permitted to open upon a partially enclosed balcony or space above a setback when: 2.1. Such balcony or space faces upon a public street, space, alley, park, highway, or right of way; or upon a yard, court, plaza, or space above a setback where such yard, court, plaza, or space above a setback complies with Section 1206; 2.2. The maximum depth of any habitable room is 30 feet (9144 mm) measured from the outer face of the exterior wall forming the partial or full enclosure of the balcony or space; 2.3. The enclosure of the balcony or space is not more than one story in height; and 2.4. The front of a partially enclosed balcony or space above a setback shall be open to the outer air with an open area equal to at least 75 percent of the floor surface area of such balcony or space.
3.Balconies, fully enclosed. Exterior openings required for ventilation shall be permitted to open upon a fully enclosed balcony or space above a setback, including sunroom and patio covers, when: 3.1. Such balcony or space faces upon a public street, space, alley, park, highway, or right of way; or upon a yard, court, plaza, or space above a setback where such yard, court, plaza, or space above a setback complies with Section 1206; 3.2. The maximum depth of any habitable room is 30 feet (9144 mm) measured from the outer face of the exterior wall forming the partial or full enclosure of the balcony or space; 3.3. The enclosure of the balcony or space is not more than one story in height; 3.4. The building is of Type I or II construction; 3.5. The outer enclosing walls of the balcony or space are glazed with an area at least 50 percent of the area of the interior enclosing walls of such balcony or space; the glazing may be clear plate glass or slow burning plastic; 3.6. At least 50 percent of the glazed area required by Exception 3.5 of this section is openable; and 3.7. No window from any bathroom, toilet room, kitchen or kitchenette shall open on such balcony or space.
4.Mezzanines and split-level rooms. Where a habitable mezzanine or portion of a split-level room or space is not directly served by an opening providing natural ventilation in accordance with Section 1203.5.1.2, such mezzanine or space shall open for its full width with no obstruction, except for railings, to an adjoining habitable room which is provided with natural ventilation. The floor area of such mezzanine or portion of the split-level room or space shall be added to the floor area of the adjoining room to compute the required ventilation in accordance with Section 1203.5.1.2.1. The combined space shall also comply with Section 1203.5.1.2.4. When required natural ventilation is not provided, mechanical ventilation shall be provided to the mezzanine and split-level rooms in accordance with the New York City Mechanical Code capable of providing 2 cubic feet per minute (0.00094 m 3 /s) of fresh air per 1 square foot (0.09 m 2 ) of floor area of mezzanine.
