Tiny home rules in Fairfax County, VA — covering tiny houses on wheels (THOWs), park model RVs, and tiny home on foundation builds — determine where they are legal and how they get permitted.
Fairfax County does not allow detached backyard tiny homes on most residential lots. The Zoning Ordinance treats a second dwelling as an Accessory Living Unit (ALU); interior ALUs require an administrative permit while detached ALUs require a special permit on lots of 2 acres or more. All construction must meet the Virginia Uniform Statewide Building Code (13VAC5-63).
Fairfax County regulates tiny homes used as second dwellings through Zoning Ordinance Chapter 112's Accessory Living Unit (ALU) provisions. Interior ALUs (within or attached to the principal dwelling) are limited to 800 sq ft or 40% of the gross floor area of the principal dwelling, whichever is less, with a maximum of 2 bedrooms, and require an administrative permit (currently $270 fee, 2-year initial approval). Detached ALUs are only permitted by special permit through the Board of Zoning Appeals on lots of at least 2 acres, with a maximum size of 1,200 sq ft. Either the principal or accessory unit must be owner-occupied and ALU occupancy is limited to 2 people. All ALU construction must comply with the Virginia Uniform Statewide Building Code (13VAC5-63), which incorporates the 2018 IRC. Virginia has not statewide-adopted IRC Appendix Q (tiny house standards); confirm whether Fairfax accepts Appendix Q designs with Land Development Services. A tiny house on wheels is treated as a recreational vehicle (HUD/ANSI A119.5) and cannot be used as a permanent residence in residential zones. Confirm with Fairfax County Zoning at 703-222-1082.
Occupying a detached backyard tiny home as a second dwelling without a special permit, or an interior ALU without an administrative permit, is enforceable through Zoning Enforcement. Living in a tiny house on wheels parked on residential property can be cited as an unpermitted dwelling.
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See how Fairfax County's tiny homes rules stack up against other locations.
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