ADU laws in Virginia

In plain words

Virginia passed a statewide law on accessory dwelling units (ADUs) in April 2026. It does not start until July 1, 2027. An ADU is a small second home on the same lot as a house. Examples are a backyard cottage, a garage apartment or a basement unit with its own kitchen and bathroom.

Zoning is the set of local rules that says what you can build where. Today, each county, city and town decides on ADUs. Some approve them at the counter, some require a special public hearing, and some do not allow them.

From July 2027, areas zoned for single-family homes must allow an ADU, with one big exception explained below. The locality must issue an ADU permit if the plans meet the law's limits. The plans must also meet local building, water, sewer and safety codes. The ADU permit fee is capped at $500, plus normal building fees.

Localities can still set some rules. They can require the owner to live in the house or the ADU when applying. They can require rentals of at least 30 days and a parking space. They can cap the size, but the cap must be at least 500 square feet on most lots. A setback is the required gap between a building and the property line. The ADU's setback cannot be bigger than the house's.

Here is the big exception. A place that already had its own ADU ordinance (a local law) before January 1, 2026 keeps its own rules. That likely covers Fairfax, Arlington, Loudoun, Alexandria and Richmond.

Homeowner association rules and deed covenants still apply. A covenant is a private rule written into a property's deed. You can build only if local rules and your property allow it.

The rules at a glance

What to do next

1. Find out which government zones your land (county, independent city or town) and read its current ADU or accessory apartment rules.
2. Ask the zoning office whether it adopted an ADU ordinance before January 1, 2026; if so, its own rules keep applying after July 1, 2027.
3. Read your HOA covenants, condo documents and deed restrictions, because the state law does not override them.
4. Check water, sewer or septic capacity, flood zone and any historic district limits early, since localities may still enforce them.
5. If you plan to rent the unit, ask about minimum lease terms (often 30 days) and any owner-occupancy affidavit.
6. If you want to build before July 2027, plan around your locality's current rules; the new section does not touch permits approved before that date.

What your town still decides

Until July 1, 2027, every Virginia county, city and town still sets its own ADU rules, and several (Fairfax County, Arlington, Alexandria, Loudoun, Richmond, Falls Church) already allow ADUs in some form, some by staff approval and some only after a special permit hearing. After that date, localities with no pre-2026 ADU ordinance must follow the state section. The final law exempts any locality that adopted an ADU ordinance before January 1, 2026, with no condition on how permissive that ordinance is (the introduced bill only exempted ordinances that did not treat ADUs as a special use). There is no new opt-out window. Localities may still require owner occupancy at the time of application only, enforce building codes, and apply water, sewer, septic, flood zone, stormwater, historic district and military airfield (AICUZ) limits. Private covenants, condo instruments and property owners' association rules are not overridden. A separate 2025 law (2025 Acts ch. 570) let comprehensive plans plan for tiny homes and ADUs, but it required nothing, and the current online Code text no longer shows that wording.

Examples of local rules

• Fairfax County: Calls them accessory living units (ALUs). Interior units get an administrative permit; detached units need a special permit from the Board of Zoning Appeals (a public hearing) and a lot of at least 2 acres. Owner must live on site, max 2 bedrooms and 2 people, interior units up to 800 sq ft or 40% of the house, detached up to 1,200 sq ft, one extra parking space, permit renewals required. Staff proposed loosening these rules in December 2025, with hearings possible by the end of 2026. Source
• Arlington County: One accessory dwelling per lot, inside the house, attached, or in a detached building, approved administratively by the Zoning Administrator (about 30 days). Owner must live in the house or the unit, max 3 occupants, size capped by house size (for example 35% of combined floor area up to 750 sq ft), one off-street space with exceptions, and setback rules for detached buildings built after May 2019. Source
• City of Richmond: Since a September 25, 2023 ordinance, one ADU is allowed with a single-family home in every residential zoning district. It may be up to one-third of the main house's floor area or 500 sq ft, whichever is greater, and must meet the zone's normal setbacks, lot coverage and height limits. Source
• Loudoun County: Per Fairfax County's December 2025 comparison: interior and detached units allowed by right, no owner-occupancy rule, one parking space per unit, size limits from 1,200 to 2,500 sq ft or 50-70% of the main house, and no minimum lot size for detached units. Source
• City of Alexandria: Per Fairfax County's December 2025 comparison: interior and detached units approved administratively, allowed with single-family, two-family and townhouse homes, owner-occupied when the permit is issued, max 3 occupants, no parking requirement, detached units 1 to 5 feet from side and rear lines. Source

What we’re still confirming

• Localities that adopted an ADU ordinance before January 1, 2026 are exempt from the new state requirement, and there's no published list of them; ask yours.
• Whether an exempt locality loses that status if it changes its ADU ordinance later isn't settled.

Laws, bills and citations

This is general information, not legal advice. Your town, village, city or county decides what can be built on your property. If something here looks out of date, email the team.