ADUs are allowed in LeonardtownTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Leonardtown, MD
Is your property eligible for an ADU?
# of Properties
1,418
Owner-occupied
70%
Zoning districts
10
Avg Home Value
$433,457
Median Lot Size
0.22 acres
Avg Income
$143,253
Residential Types:
1,418 housing units
Single Family
13%
Apts (4+ units)
2%
Other
86%
Zoning Districts:
1,900 parcels · 10 districts
PUDM
63%(1,195)
RSF
18%(344)
C-B
8%(144)
RMF
5%(99)
Other
6%(118)
ADU Rules
What can you build in Leonardtown, MD?
Leonardtown, MD follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.
Eligibility
- –Internal / Attached ADU: Special Permit
- –Detached ADU: Special Permit
Interior / Attached ADU Size Limits
- –Maximum size of 900 sq ft
- –Maximum size of 35% of the principal dwelling’s floor area
Detached ADU Size Limits
- –Maximum size of 900 sq ft and 35% of the principal dwelling’s floor area, whichever is less (measured as enclosed gross floor area, including enclosed porches)
Max Units
- –Single-family lots: 1 accessory apartment per lot (attached/internal or detached)
Owner Occupancy
- –Owner-occupancy required for seven months per year.
Parking
- –2 off-street spaces per unit; ADU parking must be screened/placed for neighborhood compatibility; PIRD waiver possible if adequate public parking nearby, subject to Mayor and Council approval
Rental Restrictions
- –Short-term/seasonal lodging prohibited; no accessory apartment may be used for commercial accommodations or summer rentals.
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.
St. Mary's County