Build Your ADU in the City of Alexandria, VA
Makara ADU designs, permits and builds accessory dwelling units to the City of Alexandria’s rules, and builds nothing else.
- ADU max size
- The greater of one third of the house floor area, or 350 sq ft on lots up to 2,500 sq ft and 500 sq ft on larger lots
- Minimum lot size
- No minimum
- Owner occupancy
- Required
- Off-street parking
- No off-street parking required for the ADU
- Allowed by
- Right, in permitted zones
- Rules current as of
- 2021-12-01
- Licensed & Insured in Virginia (Class A 2705184565)
- City of Alexandria ADU Specialists
- Full-Service: Design → Permits → Build
- Free Property Eligibility Assessment
Can you build an ADU in the City of Alexandria, VA?
City of Alexandria ADU Guidelines
The rules that decide whether, and what, you can build. The table below carries the specifics.
Generous Size Limits
For detached ADUs, the maximum first-floor footprint is 350 sq ft on lots of 2,500 sq ft or less, and 500 sq ft on larger lots — or one-third of the primary home's first-floor area, whichever is greater (confirm first-floor footprint vs. total floor area against §7-203). Attached interior ADUs cannot exceed one-third of the principal dwelling's total gross floor area.
Citywide — All R Zones
ADUs are permitted as an accessory use to single-unit, two-unit, or townhouse dwellings throughout Alexandria. Only one ADU is allowed per recorded lot. An administrative permit from the Department of Planning & Zoning is required — staff review is completed within 10 business days of a complete application.
As Low as 1 Foot
Alexandria has some of the most flexible setbacks in the region. Detached ADUs require just a 1-foot setback from side and rear lot lines — increasing to 3 feet if the wall has windows or doors. Portions exceeding 13.5 ft in height require 2.5 ft setbacks, and portions above 16 ft require 5 ft setbacks.
Up to 20 Feet
The detached ADU cannot exceed the lesser of 20 feet or the height of the primary dwelling. Note that height thresholds of 13.5 ft and 16 ft trigger increased setback requirements, so taller ADUs need to be sited carefully on the lot. All rooftop appurtenances count toward the height calculation.
Live on Site Required
The property owner must maintain the property as their primary residence at the time the ADU permit is issued. Long-term rentals of the ADU are permitted. Short-term rentals (e.g., Airbnb) are allowed for up to 120 days per calendar year — but the main house and ADU cannot both be short-term rented simultaneously.
No Parking Required
Alexandria exempts ADUs from any off-street parking requirement — a major advantage over many neighboring jurisdictions. No existing required parking spaces may be removed to accommodate ADU construction, but no new space needs to be added either. This makes ADUs viable on nearly any lot in the city.
Check Your Address
Run our free eligibility check and get the City of Alexandria’s rules applied to your exact lot in about a minute.
Check my property →| Requirement | Alexandria Standard (Zoning Ordinance §7-203) |
|---|---|
| Detached ADU max size | The greater of one-third of the main house or the lot-based figure below [confirm: first-floor footprint vs. total floor area, per §7-203] |
| Lot-based figure | 350 sq ft on lots ≤ 2,500 sq ft; 500 sq ft on larger lots (a large enough home raises the cap above this via the one-third rule) |
| Attached / interior ADU size | Up to 1/3 of the principal dwelling's gross floor area |
| Units allowed per lot | One ADU per recorded lot |
| Eligible properties | Single-unit, two-unit, and townhouse dwellings citywide |
| Side & rear setback | 1 ft minimum (3 ft where the wall has windows or doors) |
| Maximum height | Lesser of 20 ft or the primary dwelling's height (larger setbacks required above 13.5 ft and 16 ft) |
| Off-street parking | None required |
| Maximum occupants | 3 persons (one family) |
| Owner occupancy | Required — owner must reside in main house or ADU; units stay in common ownership. Only required at time of permit issuance. |
| Short-term rental | Permitted within city limits; main house and ADU cannot both be short-term rented at once; no exclusive STR use |
| Historic districts (Old Town, Parker-Gray) | Board of Architectural Review (BAR) approval required — adds review time |
| Approval path | Administrative ADU permit (Planning & Zoning, ~10 business days) + building permit (Code Administration) |
| Typical build time | Move-in ready in as little as 120 days from permit approval |
The City of Alexandria ADU Permit Process
Makara ADU handles this entire process from design to move-in, full turn-key.
- 01
Zoning & Eligibility Check
Confirm lot size, setback options, and size limits. Makara ADU does this free with our property eligibility checker — results in seconds.
- 02
ADU Permit Application
Submit administrative permit application to Alexandria's Dept. of Planning & Zoning via the APEX portal. Staff review completed within 10 business days.
- 03
Building Permit & Design
After ADU permit approval, a full building permit with architectural plans is filed with the Dept. of Code Administration. Trades permits (electrical, plumbing, mechanical) follow.
- 04
Build & Certificate
Construction, city inspections, and certificate of occupancy — your ADU is ready to occupy or rent to long-term or (within limits) short-term tenants.
City of Alexandria’s ADU Specialists
We don't build everything. We build ADUs. Based in Gaithersburg, we work with local permitting offices every week and know how each jurisdiction's rules shape what can be built.
Alexandria-Specific Knowledge
We know the nuances of Alexandria's two-step permitting process — the ADU permit through Planning & Zoning and the building permit through Code Administration. We know which neighborhoods have unique flooding, density, or historic district constraints, and how to design around them.
One Contractor, Start to Finish
Architecture, engineering, permits, foundation, framing, MEP, sprinklers, finishes, and the rental license — Makara ADU manages everything under one contract. No coordinating separate architects, engineers, and builders.
Fixed-Price Proposals
We quote your project in full before a shovel goes in the ground. No surprise change orders mid-construction — we plan for lot coverage, stormwater, and utility connections up front.
Built for Aging in Place & Family
Most of our City of Alexandria clients build to keep aging parents or adult children close. We design single-floor, accessible units that work beautifully today and adapt gracefully over time.
ADU Types We Build in the City of Alexandria
Most jurisdictions allow more than one ADU configuration. We help you choose the right one for your lot, your zone and your goals.
Detached Backyard Cottage
A fully independent structure in your backyard — up to 500 sq ft on most Alexandria lots, with setbacks as low as 1 foot from property lines. Maximum privacy for both households. With no parking required, even compact Del Ray and Rosemont lots can accommodate a detached ADU.
Attached Second Home
Add an attached ADU with its own separate entrance, kitchen, and bath. Makara ADU will collaborate with you to design the space to be functional to meet your needs while creating an aesthetically pleasing space that will add value to your life, family and your home.
Basement and Garage Conversions
Convert an existing garage or basement into a legal, licensed ADU — the most cost-effective path to added living space, and often faster to permit than new construction.
Serving All of the City of Alexandria
From the historic streets of Old Town to the bungalows of Del Ray and the neighborhoods of the West End — we build ADUs across every corner of Alexandria.
- Old Town
- Del Ray
- Rosemont
- West End
- Arlandria
- Seminary Hill
- Beverly Hills
- North Ridge
- Eisenhower
- Potomac Yard
ADUs We’ve Built Recently
A sample of ADUs we’ve built across Northern Virginia.
City of Alexandria ADU FAQ
Can I build an ADU in the City of Alexandria, VA?
Yes. Alexandria permits one ADU per lot on single-unit, two-unit, and townhouse properties citywide, under Zoning Ordinance §7-203. ADUs may be detached, attached, or interior conversions, and are approved through an administrative permit from the Department of Planning & Zoning.
How big can an ADU be in Alexandria?
A detached ADU may be up to the greater of one-third of the main house or the lot-based figure — 350 sq ft on lots of 2,500 sq ft or less, 500 sq ft on larger lots — so a home with a large enough first floor can exceed 500 sq ft. (Confirm whether the one-third is measured against the first-floor footprint or total floor area with Alexandria's §7-203.) An attached or interior ADU cannot exceed one-third of the principal dwelling's gross floor area.
What are the setback and height rules for an Alexandria ADU?
Detached ADUs require just a 1-foot side and rear setback, increasing to 3 feet where the wall has windows or doors. Height is capped at the lesser of 20 feet or the primary home's height, with larger setbacks required above 13.5 feet and 16 feet.
Does Alexandria require off-street parking for an ADU?
No. Alexandria exempts ADUs from any off-street parking requirement, though existing required parking for the main home cannot be removed to build the ADU. This makes ADUs feasible on nearly any lot in the city.
Do I have to live on the property to have an ADU in Alexandria?
Yes. Alexandria requires owner-occupancy — the owner must reside in either the main house or the ADU at the time the ADU permit is issued. The ADU and main house must remain in common ownership and cannot be sold separately.
Can I rent out my Alexandria ADU or use it for Airbnb?
Long-term rental is permitted. Short-term rental is allowed only within the city's limits, and the main house and the ADU cannot both be short-term rented at the same time — exclusive short-term rental use of the ADU is prohibited.
What about ADUs in Old Town or other Alexandria historic districts?
ADUs in the Old and Historic Alexandria and Parker-Gray districts require Board of Architectural Review (BAR) approval on top of the standard ADU and building permits. This design review adds time, so historic-district projects should plan for a longer permitting timeline.
Is Your City of Alexandria Property Eligible for an ADU?
Use our free eligibility checker to find out in about a minute, and get a personalized report sent to your inbox.