Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Alexandria ADU cost →Building an ADU in Alexandria costs between $150,000-$350,000 for new construction, with per-square-foot costs averaging $200-$400. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $80,000-$150,000, while prefab/modular ADUs fall in between at $150,000-$300,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | No separate ADU permit since June 2025 (a $135 ADU zoning-permit line remains in the FY2027 P&Z schedule; confirm). Building permit: new construction $0.75/sq ft plus $194 each electrical, plumbing, mechanical; alterations $0.30/sq ft ($95 min); plus 5% tech fee and state levy (FY26 schedule). |
| Impact Fees | None. Neither the FY2027 Planning & Zoning fee schedule nor the FY26 Code Administration schedule contains an impact or capacity fee; Virginia localities do not levy development impact fees on ADUs. Utility connection charges are set separately by the water and sewer utilities. |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. We pass your request to up to 5 local builders serving Alexandria, where we have them — free, no obligation.
Get Alexandria builder quotes →Permit fees in Alexandria are No separate ADU permit since June 2025 (a $135 ADU zoning-permit line remains in the FY2027 P&Z schedule; confirm). Building permit: new construction $0.75/sq ft plus $194 each electrical, plumbing, mechanical; alterations $0.30/sq ft ($95 min); plus 5% tech fee and state levy (FY26 schedule).. The review timeline is Not published. The city posts no residential plan-review time; only a 20-minute walk-thru review is listed for minor work such as finishing a basement (Plan Review Services Division page). Historic-district projects add a BAR hearing cycle., with plan check: Included in the building permit fee (initial review plus one corrected resubmission); optional Accelerated Plan Review at $0.045/sq ft for new residential construction or $0.075/sq ft for alterations (FY26 Code Administration schedule, sec. C).. Impact fees are None. Neither the FY2027 Planning & Zoning fee schedule nor the FY26 Code Administration schedule contains an impact or capacity fee; Virginia localities do not levy development impact fees on ADUs. Utility connection charges are set separately by the water and sewer utilities.. Pre-approved plans: Not available. No pre-approved or stock ADU plan program appears on the city's ADU page, the APEX document library or the FY2027 fee schedule..
| 1-Bedroom Rent | $2,100-$3,150/month |
| 2-Bedroom Rent | $2,300-$3,500/month |
| Annual Rental Income (est.) | $31,500/year |
| Payback Period (est.) | 7.9 years |
| Short-Term Rental | Allowed with a city short-term rental permit (Sec. |
| Overall ROI Estimate | 7-14% gross annual return |
A typical ADU in Alexandria generates approximately $31,500 per year in rental income based on average 1-bedroom rents. At an average construction cost of $250,000, the estimated payback period is 7.9 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Alexandria and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in Alexandria: $80,000-$150,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $150,000-$300,000.
3. Pre-approved plans — Alexandria does not offer a pre-approved/standard ADU plan program yet, so budget for custom architectural plans (typically $3,000-$15,000). See which cities offer pre-approved ADU plans.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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