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ADUs are allowed in Washington
Types:DetachedInternal

Accessory Dwelling Unit (ADU) Rules for Washington, DC

Is your property eligible for an ADU?

# of Properties
183,985
Owner-occupied
59%
Zoning districts
183
Avg Home Value
$995,991
Median Lot Size
0.09 acres
Avg Income
$143,691
Residential Types:
183,985 housing units
Single Family
51%
2-3 Family
5%
Apts (4+ units)
4%
Condos
3%
Other
37%
Zoning Districts:
208,033 parcels · 183 districts
RF-1
21%(43,103)
R-2
12%(24,220)
R-1B
11%(23,844)
RA-1
10%(20,296)
Other
46%(96,570)

ADU Rules

What can you build in Washington, DC?

Washington, DC follows state and local rules for Accessory Dwelling Units. Here is a concise overview of the local rules.

Interior / Attached ADU Size Limits

  • –Maximum internal/attached ADU size is 35% of the house’s gross floor area.

Detached ADU Size Limits

  • –Maximum detached ADU building area of 450 sq ft (baseline cap; larger may be allowed where 30% of the required rear yard would exceed 450 or by special exception).

Max Units

  • –R zones: 1 accessory apartment per lot.
  • –RF zones: 1 dwelling unit in an accessory building per lot; RF-1 cap 2; RF-4 cap 3; RF-5 cap 4.
  • –Alley lots: 0 accessory apartments per alley lot.

Owner Occupancy

  • –Owner must occupy the principal dwelling or ADU

Parking

  • –0 spaces per ADU; no maximum; exceptions: no parking required for a single principal dwelling or flat without 10-ft alley access in R/RF; reductions possible by special exception when impractical or unnecessary

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?

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