ADU Pass
Merrifield
No County portion
Also in: Fairfax County
ADU Pass helps homeowners in Merrifield, No County, Virginia navigate the permit paperwork for building an accessory dwelling unit. This area covers 1 ZIP code.
Map
ADU details
ADU legality: allowed-with-restrictions
ALUs permitted in Fairfax County under explicit ordinance; Merrifield's predominantly suburban single-family blocks (Pine Spring, Bren Mar) sit outside the Mosaic District PRM zoning and follow standard Fairfax ALU rules. Lot sizes are typically 0.2-0.4 acres (below the 2-acre detached threshold), so interior ALU is the practical path. Public utilities throughout. Post-July 2027 SB531 will impose statewide by-right framework with the $500 permit fee cap.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 200 | $1,500 | $120,000 | $121,500 |
| midpoint | 600 | $2,500 | $360,000 | $362,500 |
| midpoint | 800 | $3,300 | $480,000 | $483,300 |
Fee breakdown (as of 2026-05)
Permitting process
Viability (permitted uses)
- Long-term rental: with-restrictions Long-term rental of ALU permitted with required owner-occupancy. Strong tenant pool from Mosaic District workforce, Inova Fairfax Hospital, MITRE, and Tysons commuters.
- Short-term rental: with-restrictions Fairfax County STR Zoning Permit required; Merrifield's Mosaic District restaurant/retail draws plus Inova Fairfax Hospital adjacency creates moderate STR demand.
- Office rental: no Detached office rental not permitted in single-family residential districts.
- Home office: yes Home occupation permitted under Fairfax County standard conditions.
- Studio / workshop: yes Personal studio is a normal accessory use; Merrifield has growing arts community.
- Agriculture: no Merrifield parcels are dense suburban residential; agricultural use not permitted.
- Relative support: yes Multigenerational ALU is the canonical use case; SB531 post-2027 will codify family-flexible by-right.
Contacts
Utilities
- Water: Fairfax Water (serves all Merrifield) · 21d connect · $1,800
- Sewer: Fairfax County DPWES / HRSD · 28d connect · $4,500
- Electric: Dominion Energy Virginia · 21d connect · $2,400
- Gas: Washington Gas (most parcels) · 21d connect · $1,900
Property values & taxes
Construction timeline
Realistic total: best 10mo · typical 16mo · worst 24mo
Modular pathway inspectors are occasional with modular
Merrifield is served by I-66, US Route 50, and the Vienna / Dunn Loring Metro corridor; modular delivery feasible.
Financing
Insurance impact
HOA prevalence & preemption
Mosaic District itself is governed by Edens-managed master association; many Merrifield single-family subdivisions (Pine Spring, Bren Mar, Holmes Run) have HOAs.
Regulatory overlays (1)
- wetland-overlay
Fairfax County is within CBPA; most Merrifield parcels in RMA with stormwater BMP requirements.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
- Amendment
Contractor market (aggregate)
Legal history (timeline)
Current ordinance: Fairfax County Zoning Ordinance Section 4102.7.B Accessory Living Unit (single-family blocks); Mosaic District PRM Development Plan, adopted 2009-01-12, last amended 2025-06-15
- 2009-01-12 — Fairfax County Zoning Ordinance Article 4 Section 4102.7.B Accessory Living Unit (local-ordinance)
Fairfax County codified Accessory Living Unit standards: interior ALUs by Administrative Permit, detached ALUs by Special Permit; owner-occupancy required.
Effect: Established framework for ALUs across all unincorporated Fairfax including Merrifield single-family neighborhoods. - 2010-06-22 — Mosaic District Community Development Authority and PRM rezoning approval (local-ordinance)
Fairfax County Board of Supervisors approved Mosaic District as Planned Residential Mixed Use development with associated Community Development Authority for special-assessment financing.
Effect: Established Mosaic District zoning framework distinct from surrounding single-family Merrifield blocks; ALU rules apply only to those single-family blocks. - 2025-12-10 — Fairfax County ALU regulations white paper (state-guidance)
Staff white paper noting only 160 ALU approvals in 4 years countywide; ordinance amendment under review.
Effect: Active policy review may produce zoning ordinance amendment 2026-2027. - 2026-04-14 — Virginia SB531 signed by Governor Spanberger (state-law)
Statewide ADU by-right mandate; caps permit fees at $500; effective July 1, 2027.
Effect: Will challenge Fairfax County's Special Permit requirement for detached ALUs.
Known issues (2)
- policy-review — ALU is feasible only on Merrifield single-family blocks outside the Mosaic District core.
- policy-review — Interior ALU is the only practical Fairfax-permitted path in Merrifield.
County: no attribution (synthetic bucket)
No county
This city sits in the state's "no county" bucket — its ADU rules derive directly from state law and city ordinance without a county intermediary. No county-level sections apply.
Virginia state — ADU law and programs
State ADU law
Virginia has NOT enacted a statewide ADU preemption law. Virginia is a Dillon Rule state — localities possess only those powers expressly granted by the General Assembly — and the statutes granting zoning authority (Va. Code § 15.2-2280 et seq.) leave ADU regulation to local ordinances. ADU permission, setbacks, parking, size, and owner-occupancy rules therefore vary by county, independent city, and town. Virginia is unique in that it has 38 independent cities that function as counties (neither in nor subordinate to the surrounding county), meaning 'the county' for any given Virginia property may be an independent city rather than a true county. Several ADU preemption bills have been introduced in recent General Assembly sessions (2022 through 2025) without enactment; none have advanced past committee as of the Assembly's 2026 regular session adjournment.
State financing programs
Virginia does not operate an ADU-specific statewide loan, grant, or forgivable-loan program. Virginia Housing (formerly the Virginia Housing Development Authority, VHDA — rebranded 2020) administers general first-time-homebuyer, down-payment-assistance (DPA), mortgage-credit-certificate, and rehabilitation products that can be applied to ADU-adjacent purchases or improvements when eligibility criteria are met, but none target ADU construction as a distinct product. The Virginia Department of Housing and Community Development (DHCD) administers federal HOME and CDBG pass-through funds that local jurisdictions can direct toward ADU-adjacent rehab, but there is no state-level ADU-dedicated line item. Federally available products (FHA 203(k), Fannie Mae HomeReady and HomeStyle Renovation, Freddie Mac CHOICERenovation) remain the primary ADU financing path for Virginia homeowners.
State housing programs
Virginia does not run a state-level pre-approved-ADU-plan catalog, statewide impact-fee-waiver statute for ADUs, or streamlined-review mandate. State-level programs that touch ADU-adjacent policy are coordinated primarily through the Department of Housing and Community Development (DHCD) and Virginia Housing, and act by funding or assisting local jurisdictions rather than by preemption. Local ADU activity — Arlington County's Accessory Dwellings program (detached ADUs permitted since 2008, liberalized 2020), Alexandria's accessory-dwelling ordinance, Fairfax County's accessory-living-unit program, and Charlottesville's 2021 zoning-code changes — is authorized under the localities' Va. Code § 15.2-2280 zoning authority, not by state mandate.
- DHCD Community Development Block Grant (CDBG) Program — Federal CDBG funds administered by DHCD to eligible non-entitlement Virginia localities for community-revitalization, housing-rehab, and infrastructure projects. Not ADU-specific. Participating localities can direct CDBG funds toward housing-rehab projects where local policy supports ADUs.
- DHCD HOME Investment Partnerships Program — Federal HOME funds administered by DHCD to Virginia participating jurisdictions and non-profits for affordable-housing acquisition, rehab, and new construction. Not ADU-specific; can be directed to ADU-adjacent rehab at local discretion.
- Virginia Housing Commission — Permanent advisory commission of the General Assembly that studies housing-policy questions and recommends legislation. Has periodically studied ADU preemption and missing-middle housing without recommending statewide enactment as of 2026-04-21.
- Local ADU ordinances under Va. Code § 15.2-2280 authority — Not a state program — listed here because Virginia ADU policy is executed entirely at the locality level under the § 15.2-2280 zoning grant. A homeowner seeking to build an ADU consults the zoning ordinance of the specific county, city, or town where the parcel is located.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.
ZIP Code
- 22116
Post Office
- 8409 Lee Hwy, 22116