ADUs are allowed in Unincorporated BaltimoreTypes:DetachedInternal

Types:DetachedInternal

Accessory Dwelling Unit (ADU) Rules for Unincorporated Baltimore, MD

Is your property eligible for an ADU?

# of Properties

312,297

Owner-occupied

85%

Zoning districts

Avg Home Value

$383,706

Median Lot Size

0.19 acres

Avg Income

$110,520

Residential Types:

312,297 housing units

Single Family

Apts (4+ units)

Other

92%

Zoning Districts:

373,194 parcels · 62 districts

DR-5.5

39%(145,154)

DR-3.5

15%(55,798)

DR-10.5

12%(43,207)

DR-2

5%(19,303)

Other

29%(109,732)

ADU Rules

What can you build in Unincorporated Baltimore, MD?

Unincorporated Baltimore, MD follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.

Eligibility

–Internal / Attached ADU: By Right
–Detached ADU: By Right

Interior / Attached ADU Size Limits

–Maximum size of 2,000 sq ft for an internal or attached in-home apartment within a single-family house
–Maximum size of one-third of the dwelling’s total floor area for an internal or attached in-home apartment

Detached ADU Size Limits

–Maximum 1,200 sq ft for a detached accessory apartment on an owner-occupied single-family lot of one acre or more.
–Maximum 800 sq ft for a detached accessory apartment on an owner-occupied single-family lot of less than one acre.

Owner Occupancy

–Owner must reside in principal dwelling or accessory apartment

Parking

–No parking minimums or maximums stated for ADUs; parking may be set case-by-case by the Director under § 409.6.A (accessory apartments).

Rental Restrictions

–Only immediate family may occupy the ADU; renting to non-family is prohibited.

ADU State Law

What can you build in Maryland?

–Local-law mandate: By Oct 1, 2026, each legislative body must adopt a local law authorizing ADUs under this section.
–Local zoning mostly remains: The subtitle generally does not alter local zoning power except as provided, but locals must establish policies that further the subtitle's intent.
–Definition-based size cap: An ADU must be ≤ 75% of the size of the primary SF detached dwelling and subordinate in use; ADUs may be detached or attached.
–Density/growth limits: ADUs must be excluded from density calculations and from measures limiting residential growth that pertain to the lot/parcel/tract.
–Setbacks: Local law cannot set side/rear setbacks that exceed existing accessory-structure setbacks.
–Parking: If a jurisdiction adds off-street parking requirements, it must consider specified factors and provide a waiver process, and must complete a parking study before adopting such requirements.
–Alley access option: Local law may prohibit converting an accessory structure to an ADU if only vehicular access is from an alley.
–Codes/adequate facilities: Local law must provide for ADU construction meeting public health/safety/welfare standards, including building codes and adequate public facilities provisions.

What's allowed on your lot?

These are the municipality-wide rules. What's allowed on a specific property also depends on state laws, setbacks, floor area ratio, lot coverage, environmental constraints, topography, and other property-specific factors. Search your address on FutureLot to see what's allowed on your property.

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Is your property eligible for an ADU?

ADU rules in other Maryland municipalities

Rules change at the town line. Check the municipality your property is actually in.

Baltimore County

Baltimore City

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