Zoning Handbook

Accessory Dwelling Unit: A dwelling unit that is secondary to the principal single household dwelling unit in terms of gross floor area, intensity of use, and physical character, but which has kitchen and bath facilities separate from the principal dwelling and may have a separate entrance.

An accessory apartment is allowed in a principal dwelling or an accessory dwelling in R zones (except the R-19 and R-20), subject to certain conditions.

Either the principal dwelling or accessory apartment unit must be owner-occupied for the duration of the accessory apartment use.
Also, the total number of persons that can occupy the accessory apartment must not exceed three.

Accessory Apartment in a Principal Dwelling Unit

The house must have a minimum gross floor area (exclusive of the garage) in the following zones:

adu2
Zones Minimum GFA
R-1-A, R-1-B, R-19 2,000 sq. ft.
R-2, R-3, R-10, R-13, R-17, R-20 1,200 sq. ft.

Accessory apartment units may not occupy more than 35% of the gross floor area of the house. The entrance to the accessory dwelling is also regulated (see Subtitle U § 253.7 (c) and (d).)

An accessory apartment in an accesory building that does not meet the provisions of U § 253.8 may be permitted by a special exception, subject to conditions.

Accessory Apartments in an Accessory Building

  • There must be permanent access to the accessory dwelling subject to the provisions of Subtitle U § 253.8 (b) and (c).
  • The accessory building cannot be used simultaneously for any other use than as a private vehicle garage, an artist studio, or storage for a dwelling unit on the lot.
  • An accessory building that houses an apartment may not have a roof deck.
  • An accessory apartment in an accessory building that does not meet the provisions of U § 253.8 may be permitted by a special exception, if approved by the Board of Zoning Adjustment, subject to conditions.

 

R-19 and R-20 zones

Accessory apartments in the R-19 and R-20 are permitted by special exception approval of the Board of Zoning Adjustment, subject to conditions.

NOTE: Prior to renting an accessory apartment in any zone, the property owner shall obtain a Residential Rental Business License from the Department of Consumer and Regulatory Affairs and the property shall be inspected for relevant housing code compliance.


For more information on the following topics, please see the corresponding referenced sections: