D.C. Mun. Regs. tit. 12, r. 12-B303

Current through Register 71, No. 45, November 7, 2024

Rule 12-B303 - LIGHT, VENTILATION AND HEATING

Strike Section R303.1 of the International Residential Code in its entirety and insert new Section R303.1 in the Residential Code in its place to read as follows:

R303.1

Habitable spaces. All habitable spaces shall have an aggregate glazing area of not less than 8 percent of the floor area of such rooms. Natural ventilation shall be through windows, skylights, doors, louvers or other approved openings to the outdoor air. Such openings shall be provided with ready access or shall otherwise be readily controllable by the building occupants. The minimum openable area to the outdoors shall be 4 percent of the floor area being ventilated.

Exceptions:

1. The glazed areas need not be openable where the opening is not required by Section R310 and a whole- house mechanical ventilation system is installed in accordance with Section M1507, subject to Section R303.4.

2. Except for living rooms and bedrooms, the glazed areas need not be installed in rooms where Exception 1 above is satisfied and artificial light is provided capable of producing an average illumination of 6 footcandles (65 lux) over the area of the room at a height of 30 inches (762 mm) above the floor level. For purposes of Section R303, bedroom shall mean a room or space located on any level of a building and designed or intended as a space in which people sleep.

3. Use of sunroom and patio covers, as defined in Section R202, shall be permitted for natural ventilation if more than 40 percent of the exterior sunroom walls are open, or are enclosed only by insect screening.

Strike Section R303.3 of the International Residential Code in its entirety and insert a new Section R303.3 into the Residential Code in its place to read as follows:

R303.3

Bathrooms. Bathrooms, water closet compartments and other similar rooms shall be provided with aggregate glazing area in windows of not less than 3 square feet (0.3 m2), one half of which must be openable, and a local exhaust system. The minimum local exhaust rates shall be determined in accordance with Section M1507. Exhaust air from the space shall be exhausted directly to t he outdoors.

Exception: The glazed areas shall not be required where artificial light are provided.

Strike Section R303.4 of the International Residential Code in its entirety and insert new Section R303.4 in its place in the Residential Code to read as follows.

R303.4

Mechanical ventilation. Each new dwelling unit shall be ventilated by mechanical means in accordance with Section M1507.3, and shall have at least one opening to the outdoors for natural ventilation. The minimum openable area to the outdoors shall be 4 percent of the floor area of the habitable spaces.

Where an existing dwelling unit is undergoing a Level 3 alteration and its air infiltration rate is less than five air changes per hour when tested with a blower door at a pressure of 0.2 inch water column (50 Pa) in accordance with Section R402.4.1.2 of the Energy Conservation Code-Residential Provisions, the dwelling unit shall be ventilated by mechanical means in accordance with Section 403 of the Mechanical Code .

D.C. Mun. Regs. tit. 12, r. 12-B303

Final Rulemaking published at 67 DCR 5679 (5/29/2020); amended by Final Rulemaking published at 68 DCR 7439 (7/30/2021)