Arlington is progressive on ADU regulations, allowing accessory units with streamlined approval. The county's proximity to DC and strong housing market make it attractive for ADU development.
Zoning & Size Requirements [1]
Yes, you can build an ADU in Arlington. A detached ADU can be up to 1,000 sq ft under current Virginia and Arlington zoning rules.
| Allowed Zones | Single-family residential zones |
| Max Size (Detached) | 35% of combined floor area up to 750 sq ft (45% up to 500 sq ft if the main dwelling is under 1,000 sq ft); new detached accessory buildings are also footprint-capped at 560 sq ft (R-5/R-6) or 650 sq ft (other R districts) |
| Max Size (Attached) | Same 750/500 sq ft rule as detached; basement ADUs have no size cap |
| Max Size (JADU) | Not allowed |
| Max Height | Lesser of 1.5 stories or 25 ft for a detached accessory dwelling (standard since the May 2019 ordinance) |
| Max Units | 1 ADU per lot |
Setback Requirements [1]
Arlington requires a rear setback of about 5 ft for a detached ADU, and one off-street parking space is required. Owner-occupancy is required.
| Rear Setback | 5 ft (interior lots); 10 ft (corner lots) |
| Side Setback | 5 feet (to the wall) |
| Front Setback | A detached accessory dwelling must be at least 25 ft from any street and 8 ft from the main dwelling |
| Parking Required | No new space required if the lot already has any off-street parking; lots with none need 1 space only if a county study finds the block 65%+ parked |
| Owner Occupancy | Required - the owner must occupy the main dwelling or the accessory dwelling as their primary residence (recorded covenant; SB 531's changes arrive July 1, 2027) |
| Min Lot Size | None specified - eligibility is by zoning district (R-20 through R2-7) with a one-family dwelling |
Permit Process & Fees
An ADU permit in Arlington typically costs $2,800-$4,500 and takes 50-75 days, through a standard permit review.
| Approval Process | Building permit with streamlined review |
| Review Timeline | 50-75 days |
| Permit Fees | $2,800-$4,500 |
| Impact Fees | $1,000-$1,800 |
| Plan Check | 2-3 weeks |
| Pre-Approved Plans | Available |
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Construction Costs [2][3]
Building an ADU in Arlington typically costs $170,000-$340,000 ($170-$340 per sq ft); a garage conversion runs $90,000-$200,000.
| Average Build Cost | $170,000-$340,000 |
| Cost per Sq Ft | $170-$340 |
| Garage Conversion | $90,000-$200,000 |
| Prefab ADU (Installed) | $130,000-$290,000 |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
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Rental Income Potential [4][5]
A 2-bedroom ADU in Arlington rents for around $2,100-$3,000/mo, an estimated 5-7% annual return.
| Avg Rent (1 Bedroom) | $1,700-$2,200/mo |
| Avg Rent (2 Bedroom) | $2,100-$3,000/mo |
| Short-Term Rental | Not permitted |
| Est. Annual ROI | 5-7% annual return |
Explore Prefab ADU Options
Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half.
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Recent Law Changes
What's Changed Recently
- Virginia SB 531 (signed April 13, 2026; effective July 1, 2027): localities must allow ADUs by-right in single-family zones, with permit fees capped at $500 and family-relation requirements barred
- Arlington's existing accessory-dwelling ordinance (in effect before Jan 1, 2026) qualifies for SB 531's grandfather exemption
- Arlington's detached accessory-dwelling standards (lesser of 1.5 stories / 25 ft, May 2019 ordinance) remain in effect - no 2026 height change occurred
- Owner-occupancy is still required in Arlington (main dwelling or ADU) until SB 531's provisions take effect for non-exempt rules
Tips for Building an ADU in Arlington
- Arlington's DC proximity creates premium rental market
- High property costs offset by strong rents; moderate ROI
- Government workforce provides stable, long-term tenants
- Strong appreciation potential in this premium market
ADU Builders in Arlington
Looking for an ADU builder in Arlington? ADU projects need a contractor experienced with local zoning, the permit process, and utility connections — not every general contractor has built one. We match Arlington homeowners with experienced local ADU contractors who provide free, no-obligation quotes. Getting at least three bids typically saves 20-40% on the same scope.
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Accessory Dwelling Permit — Arlington County VA Planning Department — Accessed 2026-02-24
- Angi — ADU Construction Cost Data Market Data — Accessed 2026-02-24
- Angi — Local ADU Contractor Costs Market Data — Accessed 2026-02-24
- Zillow Rental Manager — Market Rent Data Market Data — Accessed 2026-02-24
- HUD Fair Market Rents Government Data — Accessed 2026-02-24
Frequently Asked Questions
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