ADUs are allowed in Unincorporated CalvertTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Calvert, MD
Is your property eligible for an ADU?
# of Properties
32,272
Owner-occupied
70%
Zoning districts
18
Avg Home Value
$380,274
Median Lot Size
0.84 acres
Avg Income
$136,832
Residential Types:
32,272 housing units
Single Family
2%
Other
98%
Zoning Districts:
50,756 parcels · 18 districts
RCD
36%(18,366)
RD
25%(12,938)
WCD
22%(11,083)
TC
7%(3,566)
Other
9%(4,803)
ADU Rules
What can you build in Unincorporated Calvert, MD?
Unincorporated Calvert, 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 is 75% of the principal dwelling’s gross floor area.
- –Maximum size is 40% of the building’s gross floor area; a basement-only unit may exceed this and occupy the full basement.
Detached ADU Size Limits
- –Maximum detached ADU size of 1,500 sq ft of enclosed floor area (including enclosed porches)
- –Maximum detached ADU size of 75% of the gross floor area of the single-family dwelling
Max Units
- –1 ADU per single-family lot
Owner Occupancy
- –Owner must occupy at least one dwelling unit on the premises.
Parking
- –1 space/ADU; must be on the same lot; driveways/garages may count for single-family detached; Zoning Officer may approve a minimum reduction based on a parking needs study
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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ADU rules in other Maryland municipalities
Rules change at the town line. Check the municipality your property is actually in.
Calvert County