Alexandria allows ADUs in residential zones with moderate regulations. The city's historic character and DC proximity create a strong housing market, though design guidelines add complexity.
Zoning & Size Requirements
| Allowed Zones | Single-family residential (non-historic) |
| Max Size (Detached) | 900 sq ft |
| Max Size (Attached) | 750 sq ft |
| Max Size (JADU) | Not allowed |
| Max Height | 30 feet |
| Max Units | 1 ADU per lot |
Setback Requirements
| Rear Setback | 15 feet |
| Side Setback | 5 feet |
| Front Setback | 20 feet |
| Parking Required | 1 space per unit |
| Owner Occupancy | Not required |
| Min Lot Size | 4,500 sq ft |
Permit Process & Fees
| Approval Process | Building permit + design review |
| Review Timeline | 70-100 days |
| Permit Fees | $3,200-$5,000 |
| Impact Fees | $1,200-$2,000 |
| Plan Check | 3-4 weeks |
| Pre-Approved Plans | Limited availability |
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Construction Costs
| Average Build Cost | $160,000-$320,000 |
| Cost per Sq Ft | $180-$360 |
| Garage Conversion | $85,000-$190,000 |
| Prefab ADU (Installed) | $125,000-$280,000 (installed) |
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| Avg Rent (1 Bedroom) | $1,650-$2,150/mo |
| Avg Rent (2 Bedroom) | $2,050-$2,900/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. Compare top prefab manufacturers.
Compare Prefab ADUs →Recent Law Changes
What's Changed Recently
- 2024: Streamlined ADU design review process
- 2023: Expanded ADU allowance in select zones
- 2024: Reduced design review timeline
- 2023: Created ADU design guidelines
Tips for Building an ADU in Alexandria
- Historic preservation is important consideration; verify zone compatibility
- Design review adds 70+ day timeline; plan accordingly
- Premium DC market supports high rents despite moderate ROI
- Walkable waterfront location attracts quality tenants
Frequently Asked Questions
Can I build an ADU in Alexandria?
Yes. ADUs are allowed in Single-family residential (non-historic) in Alexandria. The maximum size for a detached ADU is 900 sq ft. No owner-occupancy is required.
How much does an ADU cost in Alexandria?
ADU construction in Alexandria typically costs $160,000-$320,000. Garage conversions run $85,000-$190,000, and prefab ADUs cost $125,000-$280,000 (installed).
How much can I rent an ADU for in Alexandria?
Average ADU rents in Alexandria are $1,650-$2,150/mo for a 1-bedroom and $2,050-$2,900/mo for a 2-bedroom unit.
Do I need parking for an ADU in Alexandria?
1 space per unit. Check with Alexandria planning department for the latest Virginia ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Alexandria?
The permit review timeline in Alexandria is 70-100 days. Fees range from $3,200-$5,000.
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