ADUs are allowed in Unincorporated LoudounTypes:DetachedInternal
Types:DetachedInternal
Accessory Dwelling Unit (ADU) Rules for Unincorporated Loudoun, VA
Is your property eligible for an ADU?
# of Properties
119,250
Owner-occupied
85%
Zoning districts
57
Avg Home Value
$857,821
Median Lot Size
0.22 acres
Avg Income
$194,100
Residential Types:
119,250 housing units
Single Family
83%
Other
16%
Zoning Districts:
130,427 parcels · 57 districts
PDH4
35%(45,013)
PDH3
17%(21,769)
AR1
11%(14,344)
R16
5%(6,358)
Other
33%(42,943)
ADU Rules
What can you build in Unincorporated Loudoun, VA?
Unincorporated Loudoun, 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
- –Maximum ADU gross floor area by zoning: Transition/Rural/JLMA—the lesser of 70% of principal GFA or 2,500 sq ft; Urban—the lesser of 70% of principal GFA or 1,200 sq ft; Suburban—the lesser of 50% of principal GFA or 1,200 sq ft.
Detached ADU Size Limits
- –Maximum detached ADU size varies by district: Transition, Rural, and JLMA—up to 70% of the principal home’s gross floor area, capped at 2,500 sq ft; Urban—up to 70% of the principal home, capped at 1,200 sq ft; Suburban—up to 50% of the principal home, capped at 1,200 sq ft. Separate footprint caps also apply.
Parking
- –1 space/ADU; max NR; on-street credit up to 1 space within 500 ft; not on collector/arterial roads or within 0.5 mi of a high school, college/university, transit facility, or Metrorail; tandem spaces count; enclosed, unit-specific garages count as 0.5 space each.
Rental Restrictions
- –Detached/Internal ADU STR limited to 180 days per calendar year; operator must occupy the STR-adjacent unit for at least 185 days/year; only one rental contract; zoning permit required.
- –Commercial Whole-House STR allowed in not-otherwise-occupied ADU: up to 5 rooms and 10 guests per night; single rental contract; zoning permit required.
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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Learn the key rules and size limits for ADUs
Is your property eligible for an ADU?
ADU rules in other Virginia municipalities
Rules change at the town line. Check the municipality your property is actually in.
Loudoun County
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