Frederick County

Frederick County, Virginia's Department of Planning and Development (zoning, site-plan review, and land-use approvals) and Department of Inspections (building-permit, plan review, and inspection services) jointly administer ADU / accessory-apartment permitting for parcels in the unincorporated county. In Virginia's unusual geography, the independent city of Winchester is a separate jurisdiction that sits geographically surrounded by Frederick County but is not governed by the county — Winchester has its own planning, zoning, and building permit authorities. Frederick County permitting therefore applies to the unincorporated balance of the county (which is the vast majority of the county's roughly 414 square miles of land area) and to the town of Stephens City in the southeast corner. The county's permitting path for an accessory apartment is a sequenced process: (a) zoning determination by Planning and Development confirming the parcel's district and the district's accessory-apartment allowance; (b) conditional-use-permit application heard by the Planning Commission and decided by the Board of Supervisors when required by the zoning district; (c) building-permit application to the Department of Inspections; (d) health-department approval for on-site septic and well where applicable (most of Frederick County's rural-areas parcels are on private well and septic, not public utilities); (e) inspection and certificate of occupancy.

Process overview: For an accessory apartment in Frederick County: (1) applicant consults Planning and Development for a zoning verification confirming the parcel's zoning district (RA Rural Areas, RP Residential Performance, R4/R5 planned communities, B Business, M Industrial, MH Mobile Home, or HE Higher Education) and the district's accessory-apartment rule. (2) If the district requires a conditional use permit (CUP) for the accessory apartment, the applicant files a CUP application, pays the CUP fee, and the application is heard at the Planning Commission with a public-hearing notice, then decided by the Board of Supervisors. CUP decisions are legislative-quasi-judicial and typically take 60 to 120 days from application to Board decision, including advertising and hearing time. (3) Once zoning is cleared (by-right or by CUP), the applicant files a building permit with the Department of Inspections, including construction plans meeting Virginia USBC requirements, structural details, energy-code compliance (Virginia Residential Energy Code), and electrical / plumbing / mechanical sub-permits. (4) If the parcel is not on Frederick Water public sewer, the Lord Fairfax Health District must approve the septic-system capacity for the additional dwelling unit (a second unit frequently requires septic enlargement or evaluation of existing drainfield capacity). (5) Private-well adequacy is also evaluated for a second dwelling unit; a new well or a yield test may be required. (6) Inspections occur during construction (footing, framing, rough electrical / plumbing / mechanical, final), and a Certificate of Occupancy is issued at successful final inspection.

Impact fees: Virginia does not broadly authorize impact fees; Va. Code § 15.2-2317 through § 15.2-2327 permit road-impact fees only in designated impact-fee service districts (used by a minority of Virginia localities) and § 15.2-2328 et seq. authorize cash proffers and conditional-zoning-proffer systems historically used by growth counties. Frederick County does not operate a county-wide ADU-specific impact-fee program. Building-permit fees, plan-review fees, and CUP application fees are cost-recovery charges set by the Board of Supervisors and published in the county fee schedule. On-site septic-system permit fees are collected by the Lord Fairfax Health District under state fee schedules. Water and sewer connection / availability fees, where applicable (the Frederick Water service area is limited to portions of the county with public utilities), are separately administered by the Frederick Water authority. Applicants should request the current fee schedule from Planning and Development and Inspections at the time of application because fees are periodically revised by the Board. (schedule)

Frederick County, Virginia's Office of the Commissioner of the Revenue is the constitutional office responsible for real-estate assessment administration; the county's real-estate assessments are maintained on an annual reassessment cycle under Va. Code § 58.1-3252 and § 58.1-3253. Unlike California's acquisition-value system under Proposition 13, Virginia uses a fair-market-value assessment system and reassesses real property periodically. Virginia Code § 58.1-3201 requires that assessments be at 100% of fair market value. Counties may elect annual, biennial, or quadrennial general reassessments under § 58.1-3252; Frederick County reassesses annually in recent cycles. When an ADU or accessory apartment is added, the assessor picks up the additional improvement value at the next assessment cycle — the new improvement is added to the parcel's assessment record and the property's total assessed value increases to reflect the new dwelling unit's contribution to fair market value. Because Virginia is a full-reassessment-to-FMV state, there is no 'Prop 13 base-year preservation' protection: the existing primary dwelling's assessment is independently updated at each reassessment regardless of whether an ADU is added. Real-estate tax is calculated at the Frederick County Board of Supervisors' annually-adopted real-estate tax rate applied to assessed value; the rate for recent fiscal years has been set in the range typical of outer-Shenandoah-Valley counties and is published each spring by the Board when the annual budget is adopted.

Assessment policy: Frederick County reassesses real estate annually under Va. Code § 58.1-3252, with assessments targeting 100% of fair market value per § 58.1-3201. An accessory apartment or ADU addition is captured at the next assessment cycle after building-permit completion and certificate-of-occupancy issuance. The incremental assessed-value increase reflects the improvement's contribution to fair market value (not its raw construction cost, though the two are typically close for new residential construction). Real-estate taxes are billed semiannually. The Board of Supervisors sets the real-estate tax rate annually in the spring for the fiscal year beginning July 1; the rate is expressed per $100 of assessed value and is published in the county's annual budget materials. Because Virginia reassesses to full fair-market value each cycle, there is no equivalent of the Prop 13 base-year protection; an ADU addition, plus overall market appreciation on the primary dwelling, will together move the parcel's assessed value at the next annual assessment.

Frederick County, Virginia administers or cooperates in several overlay and environmental-review regimes that can affect ADU siting on unincorporated parcels: (1) the Chesapeake Bay Preservation Area program under the Virginia Chesapeake Bay Preservation Act — Frederick County lies in the Potomac River drainage and falls within the statutory Tidewater-Virginia Chesapeake Bay Preservation Area reach only in its eastern portions; however, statewide erosion-and-sediment-control rules apply generally; (2) FEMA Special Flood Hazard Areas along the county's principal watercourses — Opequon Creek, Back Creek, Cedar Creek, and tributaries of the Shenandoah River and Potomac River — subject to the county's floodplain-management ordinance; (3) historic overlay districts administered by the county's Historic Resources Advisory Board (HRAB), protecting rural-historic districts and individual landmark properties associated with the county's Shenandoah Valley and Civil War heritage; (4) karst / sinkhole geology review — Frederick County sits on carbonate bedrock in a karst-prone region of the northern Shenandoah Valley, so site-specific geotechnical review for foundation and septic design is commonly required on parcels with known sinkholes or karst features; (5) wildfire-risk considerations — while Virginia does not maintain Very-High-Fire-Hazard Severity Zones comparable to California's VHFHSZ, the Virginia Department of Forestry maintains Firewise USA program participation in some Shenandoah-Valley communities and applies the International Wildland-Urban Interface Code standards to forest-interface properties. Airport Land Use Compatibility planning is administered around Winchester Regional Airport (operated by the Winchester Regional Airport Authority), whose airport influence area extends into portions of Frederick County.

• FEMA Special Flood Hazard Areas / Frederick County Floodplain Management Ordinance — Frederick County's Chapter 165 floodplain-district article enforces FEMA NFIP minimum floodplain-management standards. Applicants should confirm effective FIRM panel numbers and BFEs at design time. FEMA is conducting ongoing FIRM updates in the Potomac drainage; owners should verify current effective panels before design commitments.
• Frederick County Historic Resources Advisory Board (HRAB) — Historic overlay and advisory review — Historic-overlay review does not typically prohibit an ADU outright but may add design-review requirements (materials, scale, siting) for construction on or adjacent to designated historic resources. Non-overlay parcels are unaffected. The Cedar Creek and Belle Grove NHP is a federal / state partnership and does not by itself create local regulatory authority over private-parcel construction outside the park boundary.
• Karst / sinkhole geotechnical review (carbonate-bedrock region) — Karst review is not a formal 'overlay' in the zoning-ordinance sense — it is a set of engineering and health-department constraints applied parcel-by-parcel. An ADU that requires a new or expanded septic drainfield on a karst-affected parcel is the category most likely to face a substantive review, including geotechnical investigation, hydrogeologic evaluation, and alternative septic-system design (sand-mound, drip-irrigation, or advanced treatment systems approved by VDH).
• Winchester Regional Airport — Airport Influence Area / land-use compatibility — An ADU proposed within the airport's influence area may need to comply with avigation-easement disclosure requirements and Part 77 height-limit considerations; meaningful noise-contour impact is generally limited to the immediate runway environs for a general-aviation airport of Winchester Regional's scale. The airport authority does not exercise direct land-use approval authority on private parcels outside airport property; its influence is through county-referred review during site-plan or CUP processes.
• Virginia Department of Forestry / Wildland-Urban Interface — There is no Frederick County-specific WUI ordinance comparable to western-state WUI regimes. Construction standards for ADUs on forest-interface parcels follow the general Virginia USBC; voluntary Firewise USA measures (defensible space, ignition-resistant materials, roof and vent design) are encouraged but not mandated by county zoning.