Some of Design 2147’s extended family members have received violations for having installed a bathroom in their cellars.  To help prevent violations and hefty fines, Design 2147, Ltd. would like to review Buildings Bulletin 2011-010 and clarify the conditions for installing a bathroom in one- or two-family dwellings.

Section 12-10 of the Zoning Resolution allows a cellar to contain accessory spaces not used for dwelling purposes.  A bathroom is generally not considered a habitable room.  Accordingly, a cellar in a one- or two-family dwelling may contain a minimally-sized powder room with two fixtures consisting of a lavatory and water closet.

However, subject to the review and acceptance of the borough commissioner, a cellar in a one- or two-family dwelling may contain a full bathroom with a lavatory, a water closet and a shower or bathtub (“three-fixture bathroom”) that complies with the requirements listed below:

1. A cellar in a one- or two-family dwelling may contain a three-fixture bathroom provided the following conditions are met:
2. The cellar is open without partitions except for enclosures for:
   • a boiler room
   • a laundry room
   • windowless storage and/or utility rooms limited to less than 60sf
3. The cellar is connected via an unenclosed stair to the residence above except for a door at the top of the stair.
4. The cellar has direct access to the outdoors via stairs and an operable door.
5. The cellar is equipped with smoke and carbon monoxide detectors.
6. The cellar does not contain any other fixtures or roughing for future fixtures; however, laundry (slop) sinks, washers, gas dryers and related piping shall be permitted.
7. The boiler room shall be enclosed with one-hour fire-rated construction and properly ventilated.
8. Where the cellar contains a garage, such garage shall be separated from the cellar by one-hour fire-rated construction.