ADUs are allowed in Unincorporated CharlesTypes:DetachedInternal

Types:DetachedInternal

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

Is your property eligible for an ADU?

# of Properties

56,526

Owner-occupied

76%

Zoning districts

Avg Home Value

$226,533

Median Lot Size

935.00 acres

Avg Income

$128,917

Residential Types:

56,526 housing units

Single Family

19%

Other

80%

Zoning Districts:

67,016 parcels · 37 districts

PUD

22%(14,929)

18%(12,115)

16%(10,775)

WCD

12%(8,086)

Other

32%(21,111)

ADU Rules

What can you build in Unincorporated Charles, MD?

Unincorporated Charles, 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 for an internal or attached ADU: in a townhouse, up to 35% of the principal dwelling; otherwise, on lots under 3 acres the lesser of 1,000 sq ft or 75% of the principal dwelling floor area, and on lots 3 acres or more, up to 75%. In the Critical Area, if density treatment is sought and the unit is not entirely within the existing dwelling without adding lot coverage, it is further capped at 900 sq ft.

Detached ADU Size Limits

–Maximum detached ADU size: on lots under 3 acres, the lesser of 1,000 sq ft or 75% of the principal dwelling’s floor area; on lots 3 acres or more, 75% of the principal dwelling’s floor area. If using Critical Area density treatment, further capped at 900 sq ft.

Owner Occupancy

–No owner-occupancy restriction.

Parking

–2 spaces/ADU; in Activity Center zones (WC/AUC) minimum may be reduced to 50% of Figure XX-1; residential max capped at 100% of Figure XX-1; on-street frontage spaces may be credited.

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.

Check my property

How can we help you?

Get matched with trusted local builders

Understand what's allowed on your property

Learn the key rules and size limits for ADUs

Learn More

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.

Charles County

Indian Head La Plata

See all municipalities in Charles County →See all Maryland municipalities →