N.Y.C. Admin. Code § BC U103: Section BC U103: General Requirements

U103.1 Scope.

All ADUs shall comply with this section and the applicable requirements in Sections U201 through U205.

U103.2 Light and ventilation of the primary dwelling.

The creation of an ADU shall not diminish the light or ventilation of any habitable rooms of the primary dwelling in any way not in compliance with Chapter 12.

U103.3 Light and ventilation of ADU.

All habitable rooms within an ADU shall be provided with natural ventilation in accordance with Section 1203.5 and natural light in accordance with Section 1205.2.

U103.4 Separate entrance required.

An ADU shall be provided with a separate entrance from that serving the dwelling units of the primary dwelling, either from the exterior of the primary dwelling or directly from a public corridor within the primary dwelling.

U103.5 Separate utility required.

An ADU shall be provided with a heating, ventilation, and air-conditioning system, electrical system, and gas piping in accordance with Section U103.5.1 through U103.5.4, provided that an ADU on a tax lot where the total number of dwelling units exceeds 2, other than an ADU constructed in accordance with section U202, shall be provided with a heating, ventilation, and air-conditioning system, electrical system, and gas piping that is separate from the primary dwelling.

U103.5.1 Heating, ventilation, and air-conditioning systems.

A primary dwelling and an ADU shall be provided with:

1. Return air openings for heating, ventilation, and air-conditioning that are not taken from another dwelling unit.

2. Separate climate controls.

U103.5.2 Electrical systems.

A primary dwelling and an ADU shall be provided with:

1. Ready access to the service disconnecting means serving the dwelling unit.

2. Ready access for each occupant to all overcurrent devices protecting the conductors supplying each dwelling unit.

U103.5.3 Gas piping.

Where an ADU is served by gas piping, such piping shall be provided with:

1. Ready access for each occupant to shutoff valves serving the dwelling unit in which such occupant resides.

2. Ready access for each occupant to appliance shutoff valves serving appliances in the dwelling unit in which such occupant resides.

U103.5.4 Water service.

A primary dwelling and an ADU may share a common potable water system, provided that there are separate, accessible main shutoff valves allowing the water to be turned off for each unit without affecting any other unit.

U103.6 Fire protection system.

ADUs shall be provided with a fire protection system in accordance with Chapter 9 unless otherwise prescribed in Section U103.6.1 through U103.6.3.

U103.6.1 Automatic sprinkler system.

Where the ADU is permitted to be classified as an R-3 occupancy by this code, the exception in Section 903.2.8 shall not apply to such ADU and such ADU shall be provided with an automatic sprinkler system throughout the ADU in accordance with NFPA 13D as modified by Appendix Q.

U103.6.1.1 Sprinkler of basement or cellar ADU.

Where permitted by Section U202.12, notwithstanding Section 901.9.2, the primary dwelling shall not be required to be sprinklered as a Group R-2 occupancy where the basement or cellar ADU is sprinklered in accordance with NFPA 13D as modified by Appendix Q and the building is provided with fire department access as described in Section 501.4.3.1 of the New York City Fire Code. The alteration or creation of such a basement or cellar ADU shall be deemed to be an alteration subject to exception 5.1 of section 501.4.3.1 of the New York City Fire Code.

U103.6.2 Smoke alarm.

All ADUs shall be provided with smoke alarms in accordance with Section 907.

U103.6.3 Carbon monoxide alarm.

All ADUs shall be provided with carbon monoxide alarms in accordance with Section 915.

U103.6.4 Gas alarm.

Where gas service is provided in an ADU, gas alarms shall be required in accordance with Section 918.

U103.7 Emergency escape and rescue openings.

All habitable rooms of an ADU shall be provided with emergency escape and rescue openings in accordance with Section 1025 of the New York City Fire Code and Section 1030.

U103.8 Fire department access.

For the purpose of Section 501.3.1, an ADU shall be considered as an accessory building. Notwithstanding any inconsistent provisions of Section 501.3.2, where the main entrance to the ADU is set back no more than 100 feet from the curb line, a fire department access path shall be provided in accordance with Table U103.8. Protruding objects, projections, or overhangs shall not reduce such minimum clear width. Such access path shall open to the sky and be unobstructed between the street and such ADU.

Table U103.8 Minimum Clear Width of Fire Department Access Path and Maximum Number of Stories of an ADU

Width of fire department access path

ADU arrangement

a

Sprinkler

c

Fire district

Construction class

Maximum building height in stories

Fire separation distance

5 ft

Attached

b

, detached, manufactured home

SP

Outside

All

2

As permitted by Table 602

5 ft

Attached

b

, detached, manufactured home

SP

Inside

IA, IB, IIA, IIB, IIIA, IIIB, VA

2

As permitted by Table 602

5 ft

Attached

b

, detached, manufactured home

SP

Inside

VB

1

As permitted by Table 602

8 ft

Attached

b

, detached, manufactured home

SP

Inside

All

2

As permitted by Table 602

a. “Attached” shall refer to ADUs constructed in accordance with Section U203. “Detached” shall refer to ADUs constructed in accordance with Section U204. “Manufactured home” shall refer to ADUs constructed in accordance with Section U205.

b. The construction class of an attached ADU shall not be lower than the primary dwelling in accordance with U203.3.1.

c. “SP” shall refer to ADUs sprinklered in accordance with this Appendix.

U103.9 Sustainable roofing zones.

An ADU with a roof constructed pursuant to Section U202.3 or U202.4 shall be exempt from the requirements for a sustainable roofing zone pursuant to Section 1512 for any roof construction attributed to such ADU.

(L.L. 2024/127, 12/18/2024, eff. 6/16/2025)