ADU Rules in Manassas, Virginia

Manassas is an independent city in Northern Virginia with approximately 43,000 residents. As an independent city, Manassas operates completely separately from Prince William County, within which it is physically located. Properties in Manassas city limits are governed by City of Manassas regulations — not Prince William County regulations. The City of Manassas Park is an additional, separate independent city in the same area, adding to the jurisdictional complexity of this region.

Manassas holds significant historical weight as the site of the First and Second Battles of Bull Run (Manassas) during the Civil War — two of the most important battles of the early war period. The Manassas National Battlefield Park is partly within and adjacent to the city. Manassas has grown substantially as a DC-area suburb, serving commuters via I-66 and the Manassas VRE (Virginia Railway Express) line, and has a diverse and growing population.

Virginia statewide ADU law status

Virginia has no enacted statewide ADU preemption: SB 304 (2024) would have required by-right ADUs, but was deferred to the Virginia Housing Commission and not enacted. Va. Code § 15.2-2292.1 covers only temporary family health-care structures. Manassas's local zoning ordinance controls whether an ADU is allowed on a specific parcel.

Manassas Local Zoning for ADUs

Manassas's zoning ordinance includes single-family residential districts (R-1, R-2, and R-3 or similar designations). Typical ADU standards include:

• Maximum size: Generally limited to 1,200 square feet or a percentage of the primary dwelling's floor area
• Unit count: One ADU per single-family lot
• Types: Detached (new rear-yard structure), attached (addition), or internal (basement, garage conversion, or attic)
• Setbacks: Detached ADUs must meet the applicable district's rear and side setbacks
• Height: Detached ADUs are typically limited to one story or approximately 16 feet
• Lot coverage: Combined coverage of all structures must not exceed the district maximum
• Utilities: Connection to city water and sewer is required where available

Contact the Manassas Department of Community Development at (703) 257-8223 or visit manassasva.gov/community-development for current ordinance provisions and any recent amendments.

Historic Old Town Manassas

Manassas has an Old Town historic district along Center Street and adjacent areas, recognized for its late 19th-century commercial and residential architecture associated with the railroad era. Properties in the Old Town historic district may require architectural review for exterior modifications. Interior ADUs and well-designed rear-yard structures in the residential portions of Old Town are generally more straightforward to approve than prominent exterior additions. Verify your property's historic overlay status with the Community Development Department.

Manassas National Battlefield Park — NPS Considerations

The Manassas National Battlefield Park encompasses parts of the city and is managed by the National Park Service. The battlefield itself is federal land not available for private development. Properties near the park boundary are subject to standard city zoning; however:

• NPS has historically expressed concerns about development that affects viewsheds or the historic character of the battlefield setting
• Any development within Section 106 review areas (near federally funded projects or on federally affected land) may trigger historic review
• For standard residential ADU projects in Manassas neighborhoods away from the immediate battlefield boundary, NPS considerations are generally not a direct barrier

Commuter Context and Housing Demand

Manassas serves as a DC-area commuter city, with VRE service on the Manassas Line and access to I-66. This creates sustained demand for housing, including rental housing. ADUs in Manassas can generate meaningful rental income from commuters or workers priced out of inner Northern Virginia. The city's growth trajectory suggests continued strong housing demand.

Stormwater and Environmental Considerations

Like much of Northern Virginia, Manassas is in the Chesapeake Bay watershed. New impervious surface — including from a detached ADU — may trigger stormwater management requirements under local ordinance and Virginia DEQ regulations. For larger impervious surface additions, a stormwater management plan may be required. Contact the Community Development Department for specific thresholds applicable to your project.

Permitting Process

1. Confirm jurisdiction — Verify your address is in the City of Manassas (not Prince William County or Manassas Park)
2. Determine zoning district and overlays — Contact Community Development, (703) 257-8223
3. Check for historic overlay — Determine if your property is in Old Town or another designated area
4. Pre-application consultation — Manassas Department of Community Development
5. Building permit application — Submit to Building and Zoning
6. Stormwater review (if applicable for new impervious surface)
7. Inspections and Certificate of Occupancy — Required before occupancy

Contact Information

• Manassas Department of Community Development: (703) 257-8223 | manassasva.gov/community-development
• Building and Zoning: (703) 257-8223
• Municipal Code: library.municode.com/va/manassas/codes/code_of_ordinances

Disclaimer: This guide provides general information only and is not legal or planning advice. Zoning regulations change over time. Always verify current requirements directly with the City of Manassas Department of Community Development and the official municipal code before making any development decisions.