Montgomery County

The Montgomery County Department of Planning and GIS Services (for zoning and Special Use Permits) and the Montgomery County Department of Inspections (for building permits, electrical, plumbing, and mechanical) share permitting authority over ADU-style projects on unincorporated parcels within the county. The county is approximately 387 square miles in southwestern Virginia in the New River Valley, bordered by Floyd County to the south, Giles County to the west, Pulaski County to the southwest, Roanoke County to the east, and Craig and Roanoke counties to the northeast. The incorporated towns within Montgomery County are the Town of Blacksburg (home to Virginia Polytechnic Institute and State University — Virginia Tech), the Town of Christiansburg (county seat), and smaller incorporated communities; parcels within those town corporate limits are permitted by the towns, not the county. Unincorporated communities permitted by the county include Riner, Shawsville, Elliston, Pilot, Prices Fork, Lafayette, Long Shop, Ironto, and others. For an ADU-style project on an unincorporated parcel, the typical sequence is: (a) pre-application zoning consultation with the zoning administrator to confirm which pathway applies (by-right family exemption, discretionary SUP, or minor subdivision); (b) if an SUP is required, application to the Planning Commission and Board of Supervisors via the statutory public-hearing process; (c) site plan review if the parcel or zoning district requires it; (d) building permit application to the Department of Inspections; (e) well and septic evaluation by the Virginia Department of Health — New River Health District for parcels not served by public utilities; (f) construction inspections; (g) certificate of occupancy. Applicants should expect a materially longer timeline than a first-dwelling build if a Special Use Permit is required, because SUP is a public-hearing process subject to statutory notice under Va. Code § 15.2-2285.

Process overview: Montgomery County's ADU-style permitting process varies by project pathway: (1) Family-member (kinship) dwelling — if the second dwelling is occupied by a family member of the primary-dwelling occupant and qualifies under the county's family-exemption provisions, the zoning administrator may issue an administrative zoning approval, followed by the standard building permit; this is the fastest path when eligible, typically 4-10 weeks end-to-end assuming no complications with well/septic or building code. (2) Special Use Permit (SUP) for a non-kin rental or market-rate second dwelling — the applicant submits a completed SUP application with site plan, statement of use, neighbor-notification list (or reliance on the statutory advertising), and the required filing fee to the Department of Planning and GIS Services. Staff conducts a zoning analysis and prepares a staff report. The Planning Commission holds a public hearing (advertised per Va. Code § 15.2-2204: once a week for two successive weeks, with final notice not less than five days before the hearing) and makes a recommendation to the Board of Supervisors. The Board of Supervisors then holds its own public hearing and votes. The entire SUP process typically takes 90-150 days from complete submission to Board decision; complex applications, applications requiring ordinance interpretation, or applications that draw significant public opposition can take longer. (3) Minor subdivision — if the applicant prefers to create a separate buildable lot and construct a fully separate dwelling, the subdivision ordinance applies; review runs through the subdivision agent and the Planning Commission. Timelines vary from approximately 30 days (simple minor subdivision with existing road frontage and utilities) to 6+ months (major subdivision with road, stormwater, or utility requirements). Building permits for a second dwelling require compliance with the Virginia Uniform Statewide Building Code (USBC) — Virginia has a single statewide building code and localities may not impose more stringent building standards. Well and septic approval (for unincorporated parcels not served by public water/sewer) is administered by the Virginia Department of Health — New River Health District, and is required before a building permit can be issued for a dwelling not connected to public utilities.

Impact fees: Virginia localities generally do not levy impact fees of the type used in California, Colorado, or Florida. Va. Code does not broadly authorize residential impact fees for counties; the narrowly enumerated road-impact-fee authority at § 15.2-2317 through § 15.2-2327 applies only to counties meeting specific growth-rate and density criteria, and Montgomery County is not among the statutorily eligible road-impact-fee counties as of 2026-04-21. Cash proffers tied to rezoning applications were historically common but are now constrained by Va. Code § 15.2-2303.4 (2016) limiting residential proffers. For an ADU built on an existing parcel without rezoning, the applicant pays building-permit fees (set by the county by ordinance and keyed to project valuation under the USBC fee schedule), any SUP application fee if applicable (SUP fees in Virginia counties typically range from $500 to $2,500 depending on parcel and project complexity), any subdivision-application fee if the minor-subdivision path is chosen, connection or tap fees if public water/sewer is available, Virginia Department of Health well/septic evaluation and permit fees for unincorporated parcels, and state-code permit surcharges. Applicants should request a current fee schedule from the Department of Planning and GIS Services and the Department of Inspections at application time. (schedule)

Montgomery County real property is assessed by the Montgomery County Real Estate Assessment Office, with tax administration handled by the Montgomery County Treasurer and personal-property and business taxation handled by the Montgomery County Commissioner of the Revenue. Virginia law requires general reassessment of real property at least once every four years for most counties under Va. Code § 58.1-3252, with more frequent cycles permitted; Montgomery County has historically conducted general reassessments on a regular multi-year cycle set by the Board of Supervisors. Unlike California's Proposition 13 acquisition-value cap, Virginia uses a fair-market-value assessment system: a parcel is assessed at 100% of fair market value as of the effective date of the reassessment, and that value stands until the next general reassessment (subject to supplemental assessment for new construction added mid-cycle). When an ADU or accessory dwelling is added to an existing parcel, the new structure is added to the assessment roll at its contributory fair market value via supplemental assessment effective from completion (building-permit final inspection); the primary dwelling's assessed value is not automatically re-triggered by the ADU construction itself, but the parcel's total assessed value rises by the ADU's contributory value. At the next general reassessment, both structures are re-valued at current fair market value together. The property-tax bill equals assessed value times the real-estate tax rate adopted annually by the Board of Supervisors in the county budget process.

Assessment policy: Virginia is a fair-market-value assessment state; a new ADU is added to the assessment roll at its contributory fair market value as a supplemental assessment effective from completion (building-permit final inspection) through the balance of the tax year. The primary dwelling's prior assessed value is not automatically reset by the ADU addition, but the parcel's total assessed value increases by the ADU's contributory value. At the next general reassessment (the county operates on a multi-year reassessment cycle mandated at minimum every four years), both the primary dwelling and the ADU are re-valued at current fair market value. Owners converting existing interior space (e.g., a basement apartment) to a permitted ADU should expect the contributory value to reflect the creation of a second kitchen, second entry, and the resulting increase in the parcel's market-rent potential; owners adding a detached ADU typically see a larger incremental assessment increase than those converting existing interior space. Property-tax rates are set annually by the Montgomery County Board of Supervisors in the county budget process; real-estate tax rates (dollars per $100 of assessed value) have historically been in the range of approximately $0.80-$0.90 per $100 in recent years, higher than some rural Virginia counties because of Montgomery County's mixed-use tax base and the service-demand impact of the Virginia Tech student population, but owners should confirm the current year's rate from the county's adopted budget since rates change annually.

Montgomery County administers or is subject to several overlay regimes that materially affect ADU siting on unincorporated parcels: (1) FEMA National Flood Insurance Program Special Flood Hazard Areas along the New River, Little River, Tom's Creek, Stroubles Creek, Elliott Creek, North Fork of the Roanoke River, and various tributaries, administered through the county's floodplain ordinance; (2) steep-slope and karst-terrain considerations across much of the county, including significant sinkhole and carbonate-rock geology in the Appalachian Valley-and-Ridge province, which affect septic siting and foundation design (Virginia Department of Environmental Quality has karst-area guidance and the Virginia Department of Health applies specific septic standards in karst areas); (3) wildfire risk tracked by the Virginia Department of Forestry in the more heavily forested western and southern portions of the county adjacent to the Jefferson National Forest, with wildfire risk elevated in the Appalachian Mountain terrain — Virginia does not have a California-style Very High Fire Hazard Severity Zone regulatory overlay with mandatory ignition-resistant construction requirements, and the Virginia Uniform Statewide Building Code has not statewide-adopted the International Wildland-Urban Interface Code; (4) Agricultural and Forestal Districts (AFDs) established under Va. Code § 15.2-4300 et seq., which provide participating landowners use-value taxation and subdivision-deferral protections in exchange for a commitment to keep land in agricultural or forestal use — Montgomery County has established multiple AFDs over the decades, and an ADU on an AFD-enrolled parcel is generally permitted for agricultural-accessory uses but may conflict with AFD purposes if proposed as non-agricultural commercial rental; (5) Chesapeake Bay Preservation Act applicability — Montgomery County is NOT in the Tidewater area covered by the Chesapeake Bay Preservation Act (Va. Code § 62.1-44.15:67 et seq.), and the New River Basin drains to the Ohio/Mississippi system, not the Chesapeake Bay, so Resource Protection Areas (RPAs) and Resource Management Areas (RMAs) do not apply; (6) Virginia Tech property and federal lands — the Virginia Tech main campus and agricultural research facilities occupy significant land in and around Blacksburg, and the Jefferson National Forest (managed by the U.S. Forest Service) occupies substantial acreage in the western/southern county — federal and state lands are outside the scope of county zoning, but adjacency to these lands affects private-parcel development on neighboring properties; (7) New River scenic-river and Wild & Scenic corridor considerations in certain segments — the New River through Montgomery County is not federally designated Wild & Scenic, but recreational, scenic, and ecological values shape some local planning attention; (8) the county does not have a broad historic-district overlay covering large portions of the unincorporated county, though individual properties (such as Smithfield Plantation in Blacksburg) are listed on the Virginia Landmarks Register or National Register and receive those federal/state protections. The absence of a Chesapeake Bay overlay is a meaningful difference from eastern Virginia counties and simplifies some environmental-review steps.

• FEMA National Flood Insurance Program — Special Flood Hazard Areas (New River, Little River, Stroubles Creek, Tom's Creek, others) — Montgomery County participates in the National Flood Insurance Program and administers a county floodplain ordinance satisfying the NFIP minimum standards. Principal Special Flood Hazard Area (SFHA) extents in the county are along the New River (the county's largest river and a major through-flowing feature), Little River, Tom's Creek (through the Virginia Tech campus and south Blacksburg area), Stroubles Creek, Elliott Creek, and various tributaries. An ADU within an SFHA must comply with NFIP elevation requirements (lowest finished floor at or above Base Flood Elevation plus any county freeboard — Virginia's Uniform Statewide Building Code sets a baseline freeboard but counties may add more), flood vent requirements on enclosed areas below BFE, anchoring requirements, and post-construction Elevation Certificate filing. Owners should confirm the current-effective FIRM panel at the FEMA Map Service Center before design; FEMA periodically updates Virginia county maps. Lenders and the NFIP Write Your Own program will require flood insurance for mortgaged SFHA parcels.
• Karst and sinkhole terrain — septic and foundation implications — Substantial portions of Montgomery County lie within the Appalachian Valley-and-Ridge carbonate-rock belt, where sinkholes, disappearing streams, and subsurface drainage pathways are common. Karst terrain materially affects ADU siting in two ways: (a) the Virginia Department of Health applies enhanced setback and design standards for on-site sewage disposal systems (septic) in karst areas to protect groundwater, which can rule out some parcels for additional dwelling-unit septic capacity or require alternative (e.g., mound, pretreatment, or low-pressure-dose) septic designs at substantially higher cost; (b) foundation design for a detached ADU on karst terrain may require enhanced geotechnical investigation and design to address sinkhole risk, adding engineering cost. The Virginia Department of Environmental Quality publishes karst-area guidance and the Virginia Geological Survey publishes sinkhole-inventory maps; owners should consult these resources and their local health district at the pre-application stage.
• Virginia Agricultural and Forestal Districts (local option under state law) — Montgomery County has established Agricultural and Forestal Districts under the state AFD Act. Enrollment is voluntary; participating landowners commit to keeping land in agricultural or forestal use for a specified term (typically 4-10 years) in exchange for use-value assessment (Va. Code § 58.1-3230 et seq.) and limited protection from certain governmental actions that would disrupt agricultural use. An ADU on an AFD-enrolled parcel is generally permitted if it is an accessory use to continued agricultural operation (e.g., a farm-labor dwelling, family-kinship dwelling, or tenant farmer residence), but non-agricultural commercial-rental ADUs may conflict with AFD purposes and trigger AFD committee review or require withdrawal from the district with possible rollback-tax consequences. Owners should consult the Montgomery County AFD Advisory Committee and the zoning administrator before assuming ADU compatibility with an AFD-enrolled parcel.
• Virginia Department of Forestry wildfire risk and Virginia Statewide Building Code WUI provisions — Virginia has wildfire risk in the Appalachian and Blue Ridge counties, and Montgomery County's western and southern mountainous edge adjacent to the Jefferson National Forest has elevated wildfire exposure. Unlike California, Virginia does not have a statewide Very High Fire Hazard Severity Zone overlay that mandates WUI-rated construction materials on a per-parcel basis. The Virginia Department of Forestry publishes wildfire risk assessments and promotes defensible-space practices, but enforcement is advisory rather than regulatory. The Virginia Uniform Statewide Building Code, which is the single statewide building code (localities cannot impose more stringent building standards), does include Appendix K of the International Wildland-Urban Interface Code only where adopted; Virginia has not statewide-adopted the IWUIC. Owners in wildfire-exposed Montgomery County locations should follow best practices but face no locality-imposed WUI construction overlay analogous to California Chapter 7A.
• Jefferson National Forest adjacency — Substantial portions of western and southern Montgomery County lie adjacent to the Jefferson National Forest (administered together with the George Washington National Forest by the U.S. Forest Service as GWJNF). The Jefferson National Forest is federal land; federal regulation applies to activities within the forest boundary, not to private parcels outside it. However, private parcels abutting the national forest may face scenic, access, wildlife, and wildfire considerations, and individual deed restrictions, conservation easements, or access easements may apply to specific parcels. Owners of parcels adjacent to the forest should check the zoning district and any recorded easements, and contact the Eastern Divide or New Castle Ranger District for any question involving access, boundary, or adjacent-use coordination.
• Virginia Tech and related state-institution land — Virginia Tech's main campus in the Town of Blacksburg, together with its extensive agricultural research, experimental, and open-space land holdings in and around Blacksburg and elsewhere in Montgomery County, is state-owned land not subject to county zoning. The university's presence is the single largest economic and demographic driver in the county. The relevance for ADU purposes is indirect but material: (a) the Virginia Tech student population drives unusually high rental demand in Blacksburg and adjacent county areas, which makes ADU-as-rental economics attractive but also draws heightened political scrutiny of near-campus rental density; (b) university expansion over time can alter zoning and infrastructure conditions on adjoining private parcels; (c) the university is not itself a permitting authority for private-parcel ADUs, but its land-use decisions shape the county development environment. Private-parcel ADU projects on parcels adjacent to Virginia Tech land should consult the Town of Blacksburg (if inside town limits) or Montgomery County (if outside town limits) for the applicable zoning, and should not assume university proximity changes the permit process.
• Virginia Dam Safety program for dams upstream of developed areas (as applicable) — Montgomery County contains several regulated dams under the Virginia Dam Safety program; dam owners bear the primary compliance obligation, but downstream parcels within a regulated dam's inundation zone may face siting, notification, or insurance considerations for new dwelling construction. This is a less common constraint than floodplain or karst and applies only to specific downstream parcels. Owners should consult the DCR Dam Safety and Floodplain Management program and the county floodplain administrator for any parcel in a dam inundation zone.