Vienna, VA Accessory Structures: Garage Conversions (2026)

The Town of Vienna regulates detached and attached garages through the Virginia USBC, Vienna Zoning Ordinance, and Fairfax County building permit administration. Any garage, whether pre-fabricated or site-built, whether attached or detached, requires a building permit regardless of size because garages are considered structures intended to shelter vehicles with significant structural, electrical, and sometimes mechanical systems, which are not covered by the small-shed USBC exemption. Permits require a site plan showing setbacks, building plans meeting USBC structural and fire separation standards, and typically electrical permits for lighting and outlets. Most Vienna single-family districts require detached garages to be in the side or rear yard with minimum setbacks of 5 to 10 feet from side and rear property lines and further from front lot lines. Maximum height is typically 15 to 18 feet measured to mid-slope roof height. Garages count toward overall lot coverage limits that include house footprint, driveway, patios, and all other impervious surfaces, which are commonly capped at 30 to 35 percent of lot area depending on district. Attached garages must meet the same setbacks as the primary dwelling and must have a rated fire-separation wall between the garage and living space under USBC (usually 5/8 inch Type X gypsum). Converting a garage into habitable living space (bedroom, office, playroom) requires building permits for framing, insulation, HVAC, and electrical upgrades, plus provision of replacement off-street parking on the lot (often in the driveway) so as not to violate Vienna parking requirements. Removing a garage door and replacing with a wall and windows is a common conversion detail. Carports are treated as accessory structures and typically require permits as well.