When does a detached garage need a building permit in Alexandria?

Garages are almost always bigger than Virginia's 256 sq ft exemption. Only one-story detached structures up to 256 sq ft are exempt.

Where do I apply for a detached garage permit in Alexandria?

Apply through APEX permit portal, or call 703-746-4200.

It depends on size and placement.

A detached garage behind the house can sit 1 ft from the side and rear lines if that wall has no windows or doors (3 ft if it does).

On lots under 8,000 sq ft the garage is capped at 250 sq ft and 11.5 ft tall; on bigger lots, 500 sq ft and 13.5 ft.

Only one such garage per lot, and it must sit completely behind the rear wall of the house.

Rules last checked by a person on October 20, 2026. Guidance only; confirm with Alexandria before you build.

Setbacks depend on your zoning district, and a flood zone can change the permit answer. Enter your address to see both.

Permit	When it applies
Building permit	Garages are almost always bigger than Virginia's 256 sq ft exemption.
Floodplain development permit	If the lot is in a FEMA special flood hazard area, all development there needs a permit.
Electrical permit	Wiring needs its own permit.Confidence: medium

Location	Completely behind the rear wall of the house
Side and rear setback	1 ft (3 ft if the facing wall has windows or doors)
Size, lots under 8,000 sq ft	250 sq ft and 11.5 ft tall
Size, lots 8,000 sq ft or more	500 sq ft and 13.5 ft tall

These garage rules don't apply in Old and Historic Alexandria or Parker-Gray, where the Board of Architectural Review decides.
Call 811 at least a few days before you dig footings or post holes. Utility locating is free.
HOA covenants and deed restrictions can be stricter than city rules. Check yours before you build.

When does a detached garage need a building permit in Alexandria?: Garages are almost always bigger than Virginia's 256 sq ft exemption. Only one-story detached structures up to 256 sq ft are exempt.
Where do I apply for a detached garage permit in Alexandria?: Apply through APEX permit portal, or call 703-746-4200.

Virginia USBC, 13VAC5-63-80 Section 108.2, Exemptions from application for permit. Checked 2026-10-20.
2. One story detached structures used as tool and storage sheds, playhouses, or similar uses, provided the building area does not exceed 256 square feet... 5. Fences of any height unless required for pedestrian safety as provided for by Section 3306 or used…
44 CFR 59.1, definition of development (NFIP). Checked 2026-10-19.
Development means any man-made change to improved or unimproved real estate, including but not limited to buildings or other structures...
44 CFR 60.3, floodplain management criteria. Checked 2026-10-19.
Require permits for all proposed construction or other development in the community...
2024 IRC R105.2, Work exempt from permit (text published by the City of Benson, AZ). Checked 2026-10-19.
One-story detached accessory structures, provided that the floor area does not exceed 200 square feet. Fences not over 7 feet high. Decks not exceeding 200 square feet in area, that are not more than 30 inches above grade at any point, are not attached to a…
City of Alexandria Zoning Ordinance § 7-2501, freestanding private garages to the rear of the main building (Municode, Supp. 103). Checked 2026-10-20.
[Applies in R-20, R-12, R-8, R-5, R-2-5 and single or two-unit dwellings in RA and RB, outside the historic districts.] For lots with a minimum of 2,500 square feet and with less than 8,000 square feet lot area, the garage shall have a floor area not greate…