ADU Code

Exactly as extracted, unformatted — for checking against the original. The readable version is easier to read.

Land Use
Subtitle 5. Accessory Dwelling Units. [Effective October 1,
2025]
§ 4-501. Definitions. [Effective October 1, 2025]
(a) In this subtitle the following words have the meanings indicated.
(b)
(1) “Accessory dwelling unit” means a secondary dwelling unit that is:
(i) on the same lot, parcel, or tract as a primary single-family detached dwelling
unit; and
(ii) not greater than 75% of the size of and subordinate in use to the primary
single-family detached dwelling unit.
(2) “Accessory dwelling unit” includes a structure that is:
(i) separate from the primary single-family detached dwelling unit; or
(ii) attached as an addition to the primary single-family detached dwelling unit.
(c)
(1) “Dwelling unit” means a single unit providing complete living facilities for at least
one individual, including, at a minimum, provisions for sanitation, cooking, eating, and
sleeping.
(2) “Dwelling unit” does not include a unit in a multifamily residential building.
(d) “Utility” means water or sewer disposal services provided by:
(1) a private company regulated under Division I of the Public Utilities Article;
(2) the Washington Suburban Sanitary Commission regulated under Division II of the
Public Utilities Article;
(3) a sanitary commission regulated under Title 9, Subtitle 6 of the Environment Article;
or
(4) a municipal authority regulated under Title 9, Subtitle 7 of the Environment Article.
§ 4-502. Applicability. [Effective October 1, 2025]
This subtitle applies only to the development of accessory dwelling units on land with a single-
family detached dwelling unit as the primary dwelling unit.
§ 4-503. Policy establishment. [Effective October 1, 2025]
(a) It is the policy of the State to promote and encourage the creation of accessory dwelling units
on land with a single-family detached dwelling unit as the primary dwelling unit in order to meet
the housing needs of the citizens of Maryland.
(b)

(1) Except as provided in this subtitle and subject to paragraph (2) of this subsection, this
subtitle does not alter or abrogate any zoning power or related authority granted to a local
jurisdiction under this title.
(2) Local jurisdictions shall establish policies that further the intent of this subtitle.
§ 4-504. Adoption of local law. [Effective October 1, 2025]
(a)
(1) On or before October 1, 2026, each legislative body shall adopt a local law
authorizing the development of accessory dwelling units in accordance with this section.
(2) A legislative body may adopt a local law that:
(i) establishes standards for accessory dwelling unit safety; and
(ii) prohibits the full or partial conversion of an accessory structure as an
accessory dwelling unit if the only vehicular access to the accessory structure is
from an alley.
(b) A local law adopted under this section shall provide for construction of accessory dwelling
units that meet public health, safety, and welfare standards, including relevant building codes and
adequate public facilities provisions.
(c) A local law adopted under this section shall exclude the development of an accessory
dwelling unit from the calculation of density and the application of any measures limiting
residential growth that pertain to the lot, parcel, or tract proposed for the development of the
accessory dwelling unit.
(d) A local law adopted under this section may not establish setback requirements that exceed the
existing accessory structure setback requirements from the side and rear lot lines.
(e)
(1)
(i) A local law adopted under this section may establish additional off-street
parking requirements that consider:
1. the cost to construct off-street parking spaces;
2. whether sufficient curb area exists along the front line of the property to
accommodate on-street parking;
3. the increase in impervious surface due to the creation of new off-street
parking and the relation to any applicable stormwater management plans;
and
4. variability due to the size of the lot, parcel, or tract on which the
accessory dwelling unit or primary dwelling is located.
(ii) A local law adopted under this paragraph shall provide for a waiver process
from the parking requirements.
(2) Before adopting a local law under paragraph (1) of this subsection, a legislative body
shall complete a parking study to determine the applicable needs and restrictions in the
jurisdiction.

Real Property
§ 2-126. Unreasonable limitation. [Effective October 1, 2025]
(a)
(1) In this section the following words have the meanings indicated.
(2) “Accessory dwelling unit” has the meaning stated in § 4-501 of the Land Use Article.
(3) “Restriction on use” includes any covenant, restriction, or condition contained in:
(i) A deed;
(ii) A declaration;
(iii) A contract;
(iv) The bylaws or rules of a homeowners association;
(v) A security instrument; or
(vi) Any other instrument affecting:
1. The transfer or sale of real property; or
2. Any other interest in real property.
(b)
(1) Except as provided in paragraph (2)(ii) of this subsection, if a property owner has the
exclusive right to use the property and abides by all applicable laws and regulations, a
restriction on use regarding land use may not impose or act to impose an unreasonable
limitation on the ability of the property owner to develop or offer for rent an accessory
dwelling unit.
(2) For the purpose of paragraph (1) of this subsection, an unreasonable limitation:
(i) Includes a limitation that prohibits, either explicitly or by effect of the
restrictions, the development of an accessory dwelling unit; and
(ii) Does not include a limitation on the short-term rental of an accessory dwelling
unit.
(c) This section does not apply to a restriction on use on historic property that is listed in or
determined by the Director of the Maryland Historical Trust to be eligible for inclusion in the
Maryland Register of Historic Properties.