Kilmarnock

Northumberland County does NOT maintain a standalone accessory-dwelling-unit ordinance with dedicated definitional and dimensional standards. ADUs in Northumberland County are regulated indirectly through the Zoning Ordinance's treatment of 'accessory use,' 'accessory structure,' 'guest house / guest cottage,' and 'family-occupied second dwelling' in combination with the per-district use schedules. In the A-1 Agricultural / Residential and A-2 Rural Conservation districts, which cover the great majority of county acreage outside the waterfront R-1 areas and the village cores at Heathsville, Burgess, Callao, and Reedville, a 'family-member dwelling' or farm-labor tenant dwelling is typically permitted subject to minimum lot area (commonly 3 to 10 acres depending on the district and the familial relationship), demonstrated agricultural or family-member use, and Zoning Administrator approval; a fully independent second dwelling for non-family occupancy typically requires a Special Use Permit from the Board of Supervisors after Planning Commission recommendation. In the R-1 Limited Residential district (which covers the great majority of Chesapeake Bay, Potomac River, and interior-tidal-creek waterfront lots), a 'guest cottage' or detached accessory structure without independent kitchen facilities is generally permitted as a by-right accessory structure subject to setback, height, and lot-coverage standards; a second independent dwelling on the same waterfront parcel requires an SUP and typically encounters Chesapeake Bay Preservation Area RPA-buffer constraints that make siting difficult. In the R-2 General Residential district (denser residential areas adjacent to Heathsville and to the small Reedville, Burgess, and Callao village cores), accessory-structure rules apply with tighter setback standards. Applicants should confirm current ordinance text with the Zoning Administrator before committing to a project pro forma — the ordinance has been amended periodically and specific ADU-like allowances vary by district and by interpretation of the 'customarily incidental' accessory-use standard.

Northumberland County administers several overlay regimes that bear materially on ADU projects, and coastal / tidal exposure is the single most important physical constraint on county land use — even more so here than in most Northern Neck counties, because Northumberland occupies the tip of the peninsula and therefore has shoreline on three sides (Potomac to the north, Chesapeake Bay to the east, Great Wicomico to the south). The relevant overlays are: (1) a Floodplain Overlay District tied to FEMA Special Flood Hazard Areas, covering a very large share of the county given the low-elevation tip-of-peninsula geometry; (2) Chesapeake Bay Preservation Act jurisdiction across the entire county (Northumberland is a Tidewater locality designated under Va. Code § 62.1-44.15:67 et seq.), with Resource Protection Area (RPA) buffers of 100 feet from perennial water bodies and tidal wetlands and Resource Management Area (RMA) coverage on effectively all remaining landward extent; (3) Virginia Marine Resources Commission (VMRC) tidal-wetlands and subaqueous-bottom jurisdiction reaching any project touching tidal waters, wetlands, dunes, or beaches — unusually active here because of the working-fishery economy centered on Reedville; (4) locally-adopted historic overlays and NRHP-listed corridors including the Reedville Historic District (a remarkably intact late-19th-century menhaden-fishing-industry village), St. Stephen's Episcopal Church and other NRHP-listed chapels and plantations, and scattered colonial-era village cores; (5) state natural-area-preserve land at Hughlett Point Natural Area Preserve and Dameron Marsh Natural Area Preserve on the Chesapeake Bay frontage, with adjacency impacts on permitting for nearby parcels. Northumberland County has NO California-style coastal commission (Virginia has no coastal-commission analog; coastal regulation flows through the CBPA, the VMRC for tidal-wetlands permits, and local ordinances), NO CalFire-equivalent WUI regulatory overlay (Virginia has no statewide WUI overlay), and NO seismic-retrofit overlay. However, the combination of pervasive floodplain, pervasive CBPA, regular VMRC joint-permit triggers, and the unusually long shoreline-per-area ratio make this one of the most overlay-dense rural counties in Virginia despite its modest population of roughly 13,000.

• Floodplain Overlay District
• Chesapeake Bay Preservation Act (CBPA) Resource Protection Area and Resource Management Area
• Virginia Marine Resources Commission (VMRC) tidal-wetlands, subaqueous-bottom, and sand-dune jurisdiction
• Reedville Historic District and scattered NRHP-listed plantations, chapels, and village cores

Northumberland County's Department of Planning and Zoning handles zoning permits, Special Use Permits, site plan review, subdivision review, and Chesapeake Bay Preservation Area administration for every parcel in the county except the Kilmarnock town portion (administered by the Town of Kilmarnock) and state/federal land. Building Inspections issues building permits and trade permits for the same non-town territory. A typical ADU-like permit bundle (where a second dwelling is permitted) includes: (1) a Special Use Permit from the Board of Supervisors with Planning Commission recommendation, unless the parcel qualifies for an A-1 / A-2 family-member or farm-labor dwelling allowance, (2) a Zoning Permit confirming use compliance and district setback compliance, (3) a Building Permit with stamped residential plans, (4) Electrical, Plumbing, and Mechanical trade permits, (5) a Virginia Department of Health (VDH) - Three Rivers Health District construction permit for well and/or septic on parcels not served by public water or sewer (which is the great majority of parcels — public sewer coverage is limited to portions of the Kilmarnock town footprint and small service-district pockets), (6) a Floodplain Development Permit if any portion of the parcel is within the mapped Special Flood Hazard Area — which is a LARGE fraction of parcels in Northumberland County because the county is a peninsular tidewater jurisdiction with the Potomac River estuary to the north, the Chesapeake Bay to the east, and extensive internal tidal creek, marsh, and estuarine systems including the Great Wicomico, Coan, Yeocomico, and Little Wicomico rivers plus Cockrell's Creek (Reedville), Indian Creek, Dividing Creek, and Mill Creek, (7) a Chesapeake Bay Preservation Act review — Northumberland County IS a Tidewater locality subject to the CBPA, with Resource Protection Area (RPA) and Resource Management Area (RMA) rules applying across nearly the entire county given its tidal geometry, (8) a Virginia Marine Resources Commission (VMRC) permit for any work below mean high water or encroaching on tidal wetlands (very common in a county where working-waterfront and fishing-port infrastructure is embedded in the land-use pattern), (9) a US Army Corps of Engineers permit where federal waters are involved, and (10) Historic District review if the parcel is within a designated local historic overlay (the Reedville Historic District and scattered NRHP-listed plantations, chapels, and village cores).