Accessory Structures in Maryland (2026)
52 rules on the books across Maryland, 14 cities and counties. Select a rule to read the full details.
Severity: Few Restrictions · Light Restrictions · Some Restrictions · Significant Restrictions · Heavy Restrictions
ADU Rules
Rules for building accessory dwelling units (granny flats, in-law suites) including size limits, parking requirements, and owner-occupancy rules.
Washington County
Heavy RestrictionsWashington County, Maryland's Zoning Ordinance flatly bars turning a garage, shed or other accessory building into…
Read full rule →Montgomery County
Significant RestrictionsMontgomery County requires DHCA to license any accessory dwelling unit before it is occupied or rented, unless it was…
Read full rule →Annapolis
Some RestrictionsAnnapolis allows one accessory dwelling unit per lot, caps standalone ADUs at 850 square feet, requires a Chapter 17.44…
Read full rule →Anne Arundel County
Some RestrictionsAnne Arundel County allows one accessory dwelling unit per lot in an attached suite, garage, or detached structure…
Read full rule →Baltimore County
Some RestrictionsBaltimore County allows an accessory apartment as a temporary use in an owner-occupied single-family home or accessory…
Read full rule →Carroll County
Some RestrictionsCarroll County zoning allows one accessory dwelling unit per lot in the Residential Districts, attached or detached…
Read full rule →Charles County
Some RestrictionsCharles County allows one accessory apartment per single-family home, in the main house or in a detached accessory…
Read full rule →Gaithersburg
Some RestrictionsGaithersburg allows one accessory dwelling unit per single-family lot under section 24-5.2 of the zoning code. A…
Read full rule →Harford County
Some RestrictionsHarford County allows one accessory dwelling unit (ADU) per lot in the AG, RR, R1-R4, RO and VR Districts under §…
Read full rule →Howard County
Some RestrictionsHoward County permits an accessory dwelling unit inside an owner-occupied single-family home. The owner must live in…
Read full rule →Rockville
Some RestrictionsA detached Accessory Dwelling Unit in Rockville must sit on a permanent foundation and stay at or under 75% of the main…
Read full rule →Wicomico County
Some RestrictionsIn unincorporated Wicomico County, an accessory apartment needs Board of Appeals special exception approval under…
Read full rule →ADU Impact Fees
Impact fees, school fees, utility hookup charges, and waivers for ADUs. Many jurisdictions exempt ADUs under 750 sq ft from impact fees per state law.
ADU Owner Occupancy
Whether the property owner must live on-site to operate an ADU, deed-restriction requirements, and recent state-law changes lifting owner-occupancy rules.
Annapolis
Significant RestrictionsAnnapolis requires the property owner to live in either the accessory dwelling unit or the principal structure: an…
Read full rule →Howard County
Significant RestrictionsHoward County property owners who add an accessory dwelling unit must swear, on the initial rental license application…
Read full rule →Rockville
Significant RestrictionsOwners of a Rockville one-family home with an accessory-apartment special exception must certify annually where they…
Read full rule →Wicomico County
Significant RestrictionsIn unincorporated Wicomico County, an accessory apartment only qualifies as a legal use if it sits within an…
Read full rule →Anne Arundel County
Some RestrictionsAnne Arundel County allows one accessory dwelling unit per lot and only requires owner-occupancy of the principal home…
Read full rule →Harford County
Some RestrictionsHarford County allows one accessory dwelling unit per lot in the AG, RR, R1-R4, RO and VR Districts, but only to house…
Read full rule →Montgomery County
Some RestrictionsAn accessory dwelling unit rental license requires the owner to live in either the main house or the ADU as their…
Read full rule →ADU Rental Restrictions
Whether an ADU can be rented short-term (Airbnb), 30-day minimums, separate rental licenses, and long-term lease requirements.
Annapolis
Significant RestrictionsAnnapolis requires a rental license under Chapter 17.44 for any accessory dwelling unit, and the ADU and principal…
Read full rule →Harford County
Significant RestrictionsHarford County's accessory dwelling unit rule is not a general rental license: § 267-28B(8)(a) states its purpose is…
Read full rule →Montgomery County
Significant RestrictionsMontgomery County requires a separate license before renting out an accessory dwelling unit, and caps occupancy at two…
Read full rule →Rockville
Significant RestrictionsRockville, Maryland bars a landlord from holding rental licenses for both a house and its accessory apartment at once…
Read full rule →Anne Arundel County
Some RestrictionsAnne Arundel County allows one accessory dwelling unit per lot, but the ADU or the principal home may be rented…
Read full rule →Howard County
Some RestrictionsA Howard County property with an accessory dwelling unit can have only one of its two dwellings under a rental license…
Read full rule →Shed & Carport Rules
When a storage shed or carport needs a permit, the square-footage exemption thresholds, and the setback and height limits that apply either way.
Annapolis
Some RestrictionsAnnapolis classifies carports and garages as accessory structures allowed by right, but its bulk regulations table sets…
Read full rule →Anne Arundel County
Some RestrictionsIn Anne Arundel County, a detached shed under 150 square feet and 10 feet tall accessory to a house needs no building…
Read full rule →Baltimore County
Some RestrictionsA Baltimore County building permit is required for any shed, gazebo, or accessory structure larger than 120 square…
Read full rule →Carroll County
Some RestrictionsCarroll County exempts small detached sheds from a building permit only if they meet strict limits: no more than 150…
Read full rule →Cecil County
Some RestrictionsCecil County deleted the International Building Code's standard exemption for small sheds. Under § 157-2 of the Code of…
Read full rule →Charles County
Some RestrictionsA shed or other accessory structure in Charles County's agricultural, rural, or residential zones needs a zoning…
Read full rule →Gaithersburg
Some RestrictionsGaithersburg keeps accessory structures like sheds out of the front yard, sets a 2-foot setback for structures 200…
Read full rule →Harford County
Some RestrictionsIn unincorporated Harford County, a shed or detached garage counts as an accessory structure under § 267-27 of the…
Read full rule →Howard County
Some RestrictionsA carport in Howard County is an accessory structure subject to Section 128.0 zoning rules. Detached accessory garages…
Read full rule →Montgomery County
Some RestrictionsIn Montgomery County's Residential Detached zones, all your sheds and accessory buildings combined cannot exceed 50% of…
Read full rule →Prince Georges County
Some RestrictionsUnder the 2022 Zoning Ordinance (Sec. 27-5202), a shed or detached accessory structure may not sit in a required front…
Read full rule →Rockville
Some RestrictionsRockville zoning treats a carport as an accessory structure: it can't share a wall or roof with the house except…
Read full rule →Washington County
Some RestrictionsWashington County's Zoning Ordinance lets a single-story utility or storage shed of 100 square feet or less sit just 8…
Read full rule →Wicomico County
Some RestrictionsIn unincorporated Wicomico County, a portable, one-level accessory structure of 250 square feet or less skips the…
Read full rule →Garage Conversions
Rules for converting a garage into living space, including whether you need to replace the lost parking and what building codes apply.
Anne Arundel County
Some RestrictionsConverting a garage into living space counts as an accessory dwelling unit under Anne Arundel County Code § 18-10-124…
Read full rule →Baltimore County
Some RestrictionsA detached garage is an accessory structure subject to BCZR Section 400: it must be subordinate in area to the house…
Read full rule →Charles County
Some RestrictionsConverting a garage or other accessory building into a living space in Charles County requires county Health Department…
Read full rule →Howard County
Some RestrictionsIn Howard County a detached garage is an accessory structure that cannot contain a full bathroom, full kitchen, or…
Read full rule →Prince Georges County
Some RestrictionsConverting a garage into living space in Prince George's County requires DPIE building permits and must meet the 2022…
Read full rule →Wicomico County
Some RestrictionsConverting an attached garage into living space in unincorporated Wicomico County creates an accessory apartment, which…
Read full rule →Tiny Homes
Zoning rules for tiny houses on wheels and foundations, including minimum square footage requirements and where they can be placed.
Prince Georges County
Heavy RestrictionsThe 2022 Zoning Ordinance has no 'tiny house' use, and a manufactured home, recreational vehicle, or travel trailer may…
Read full rule →Anne Arundel County
Some RestrictionsAnne Arundel County has adopted the International Residential Code's Appendix AQ, giving tiny houses their own…
Read full rule →Baltimore County
Some RestrictionsBaltimore County has no separate tiny-home zoning category. A tiny house on a permanent foundation can qualify only as…
Read full rule →Charles County
Some RestrictionsCharles County wrote Appendix AO, Tiny Houses, of the 2021 International Residential Code directly into its local…
Read full rule →Howard County
Some RestrictionsHoward County has no standalone tiny-home zoning category. A permanent tiny dwelling is regulated as an accessory…
Read full rule →Rockville
Some RestrictionsRockville's residential code adopts IRC Appendix Q in full, giving tiny houses their own building standard instead of…
Read full rule →