ADU Guide · Verified 2026
Building an ADU in Virginia
Today, whether you can build an ADU in Virginia is decided entirely by your local city or county — there is no statewide ADU right in force right now. That changes on July 1, 2027, when Senate Bill 531 takes effect and requires every locality to allow at least one ADU by right on single-family lots. The law was signed in 2026 but is not active yet, so until mid-2027 the answer depends completely on your local zoning ordinance.
Quick Facts
Statewide floors set by Local zoning under the Code of Virginia (statewide SB 531 effective July 1, 2027). Your city may be more generous but cannot go below them.
The Three Types of ADU
Where things stand today
As of now there is no statewide ADU right in force in Virginia. Cities and counties decide whether ADUs are allowed, in which zones, and under what conditions — and the rules vary sharply, with much of Northern Virginia historically making ADUs hard or impossible to build. If you are planning an ADU right now, the reliable answer comes from your local planning department: confirm whether your zone allows an ADU, whether a special-use permit is required, and what size and setback limits apply.
What changes on July 1, 2027
Senate Bill 531, signed in 2026, creates Virginia's first statewide ADU framework, but it takes effect July 1, 2027. From that date, every locality must allow at least one ADU by right on a qualifying single-family lot — meaning no special-use permit, conditional-use permit, or discretionary board approval for a qualifying unit. Localities cannot require setbacks greater than those for the primary dwelling or other accessory structures, and cannot impose family-relation requirements between the ADU occupant and the main-home occupant. Permit fees will be capped at $500.
Why the effective date matters
This is the single most important thing to get right about Virginia: the law exists but is not active yet. Guidance that says ADUs are "now allowed by right statewide" is describing the future state, not today. Until July 1, 2027, a locality that currently prohibits or restricts ADUs is still within its rights to do so. If you want to build before mid-2027, you are working entirely under local rules; if you are planning for after, starting design and permitting early puts you ahead of the backlog that is expected when the law takes effect.
The size approach (parity, not a cap)
SB 531 does not set a statewide square-footage cap. Instead it uses a parity approach: once effective, localities cannot impose size-related restrictions on an ADU that are more restrictive than what they apply to the primary home or other accessory structures on the same lot. So the practical size limit comes from your zone's existing dimensional rules, applied evenhandedly, rather than a special ADU number. Local size rules still apply in full until the law takes effect.
An ADU stays tied to your home
Under SB 531 an ADU must remain an accessory use to the primary dwelling — it cannot be subdivided onto its own lot or sold off separately. So while an ADU adds value, rental income, and flexibility, it is legally part of your property, not a separate asset you can sell independently. This matches how most states treat ADUs and is worth understanding before you plan around resale.
HOAs are exempt
A crucial limit on the coming law: community associations are exempt from SB 531. That means even after July 1, 2027, if your property is governed by an HOA whose covenants restrict or prohibit accessory dwelling units, those private CC&Rs can still block your ADU regardless of the statewide right. Before planning, pull your HOA governing documents and check for accessory-structure and additional-dwelling-unit language — the state law will not override them.
What people get wrong
The biggest mistake is treating SB 531 as current law. It was signed in 2026 but does not take effect until July 1, 2027, so today ADUs are a purely local question in Virginia. The second mistake is assuming the statewide right will override an HOA — it will not, because associations are exempt. Confirm both your local ordinance (for now) and your HOA covenants (for now and later) before committing to a design.
From Idea to Move-In: The Timeline
Who Administers It
Check Your County
Select your county for local rules, fees, and your building department's contact details:
Building It Yourself? Here's What You'll Need
Planning an ADU? Tools homeowners use in the design and layout phase:
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Check Your Local Rules
Your city may allow more than the state floor
State law sets the minimum; many Virginia cities are more generous. Confirm specifics with your local planning department.
Find your county building department →Not sure if your project needs a building permit, a zoning approval, or both? See our guide to building permits vs. zoning approval.
Official Sources
ADU law changes frequently and local ordinances add detail. This guide is general information, not legal advice — always confirm with your local building department. Reviewed by the StateDataIndex Editorial Team · Updated August 2026.