ADUs are allowed in Unincorporated ArlingtonTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Arlington, VA
Is your property eligible for an ADU?
# of Properties
61,112
Owner-occupied
57%
Zoning districts
51
Avg Home Value
$1,218,877
Median Lot Size
0.25 acres
Avg Income
$172,325
Residential Types:
61,112 housing units
Single Family
52%
2-3 Family
4%
Apts (4+ units)
39%
Other
6%
Zoning Districts:
69,846 parcels · 51 districts
R-6
27%(19,084)
RA14-26
13%(8,893)
R-10
8%(5,483)
RA6-15
8%(5,300)
Other
45%(31,086)
ADU Rules
What can you build in Unincorporated Arlington, VA?
Unincorporated Arlington, VA 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
- –Upper limit for an internal/attached ADU: if the main dwelling’s GFA is at least 1,000 sq ft, the lesser of 750 sq ft or 35% of combined main+ADU area (solved as 0.35/0.65 × main GFA); if under 1,000 sq ft, the lesser of 500 sq ft or 45% of combined area (solved as 0.45/0.55 × main GFA). Note: an ADU wholly within a basement may be as large as the entire basement (exception not modeled here).
Detached ADU Size Limits
- –Maximum detached ADU size: 750 sq ft or 35% of combined floor area when the main dwelling is at least 1,000 sq ft; otherwise 500 sq ft or 45% of combined floor area.
Max Units
- –1 ADU per lot (single-family; attached or detached).
- –1 ADU per lot for semidetached/townhouse lots (not allowed if the lot has a family/caregiver suite).
- –0 ADUs per lot on lots containing duplex or multi-family dwellings.
Owner Occupancy
- –No owner-occupancy requirement.
Parking
- –1 space/ADU; new space may be waived if block is <65% parked; maintain existing spaces (1–2 must be kept; if >2, at least 2); base dwelling minimums apply (1 per unit, or 2 if fronting a cul-de-sac).
Rental Restrictions
- –Short-term rentals only as accessory homestay with 185+ days/year primary residence, permit required, and ADU limited to 3 lodgers
ADU State Law
What can you build in Virginia?
- –Virginia does not have a statewide ADU mandate; ADU rules are set by individual municipalities.
- –Building/fire codes are set statewide, but whether an ADU is allowed is local zoning.
- –SB 304 would have mandated ADUs. It passed the Virginia Senate in 2024 but was continued/left in House committee (i.e., not enacted statewide)
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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