ADU Pass
Grottoes
Rockingham County portion
Also in: Augusta County
ADU Pass helps homeowners in Grottoes, Rockingham 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
Grottoes ADUs follow town zoning with South River Floodplain Overlay review on river-adjacent parcels and Grottoes WWTP capacity sign-off. Grand Caverns tourism, poultry-industry workforce, and Harrisonburg-metro commuter demand all support ADU economics. The county-straddling configuration requires careful parcel-location confirmation. SB 531 preempts effective July 1, 2027.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 200 | $1,560 | $51,500 | $53,060 |
| 600 | 600 | $1,560 | $154,800 | $156,360 |
| midpoint | 700 | $1,560 | $180,600 | $182,160 |
| 1000 | 1,000 | $1,560 | $258,000 | $259,560 |
| maximum | 1,200 | $1,560 | $309,600 | $311,160 |
Fee breakdown (as of 2026-05)
Permitting process
Viability (permitted uses)
- Long-term rental: yes Long-term rental is permitted; Harrisonburg-metro and Staunton commuter demand support steady tenant flow. Grottoes is one of the more affordable workforce-housing options in the metro area.
- Short-term rental: with-restrictions Grottoes STR demand is meaningful, anchored by Grand Caverns (approximately 80,000-100,000 annual visitors) and proximity to Shenandoah National Park / Skyline Drive (~20 miles east via US 33). Town STR registration policy and Va. Code § 58.1-3819 transient-occupancy tax apply.
- Office rental: with-restrictions Detached office rental in R-1/R-2 requires Home Occupation permit; SUP for non-resident-employee use.
- Home office: yes Home occupation is a permitted accessory use.
- Studio / workshop: yes Personal studio is a permitted accessory use.
- Agriculture: with-restrictions In-town residential districts have limited agriculture allowance; production agriculture is concentrated on surrounding unincorporated Rockingham and Augusta County A-1 parcels.
- Relative support: yes Multi-generational accessory dwelling is permitted. Grottoes' affordable housing stock and Mennonite multi-generational household patterns in the broader region make this a recurring use case.
Incentives
Contacts
Utilities
- Water: Town of Grottoes Water Department (municipal water distribution; South River intake with treatment; ~1,300 connections) · 24d connect · $2,800
- Sewer: Town of Grottoes Wastewater Treatment Plant (Grottoes WWTP, South River discharge under VPDES permit; HRRSA does not extend to Grottoes) · 32d connect · $3,650
- Electric: Shenandoah Valley Electric Cooperative (SVEC) serves Grottoes (the Rockingham-side and Augusta-side town parcels alike are predominantly SVEC). · 21d connect · $1,850
- Gas: Bottled propane (no natural gas distribution to Grottoes) · 14d connect · $1,750
Property values & taxes
Construction timeline
Realistic total: best 7mo · typical 10mo · worst 17mo
Modular pathway inspectors are occasional with modular
Financing
State ADU loans:
Insurance impact
HOA prevalence & preemption
Virginia has no HOA-ADU preemption. Grottoes' older town lots are largely covenant-free; a handful of post-1995 subdivisions on the western edge carry HOA covenants.
Regulatory overlays (2)
- flood-zone
Grottoes parcels along the South River, Mill Creek, and lower-elevation rear-yard areas in the eastern third of town are in mapped Zone AE. ADU finished-floor elevation must clear Base Flood Elevation plus Virginia freeboard. Substantial Improvement (50% threshold) review on SFHA parcels. (map) - other
Grottoes sits over the Grand Caverns / Madison Cave karst system. ADU site selection in the immediate cave vicinity (Grand Caverns Regional Park's south Grottoes neighborhood) should avoid surface karst sinkholes and consider geotechnical review for foundation work. The cavern itself is a National Historic Landmark; tour operations may impose temporary construction-noise constraints during tour seasons. (map)
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
- Amendment
- Amendment
- Amendment
Contractor market (aggregate)
Legal history (timeline)
Current ordinance: Town of Grottoes Zoning Ordinance, adopted 1972-01-01, last amended 2024-01-01
- 1806-09-01 — Grand Caverns opens for public tours (oldest US show cave) (industrial-anchor)
Grand Caverns opened for public tours in 1806, making it the oldest continuously operating show cave in the United States. The cavern is a National Historic Landmark and Virginia State Geologic Landmark; tour operations have continued for over 200 years and define the town's tourism economy.
Effect: Grand Caverns tourism (approximately 80,000-100,000 annual visitors) supports STR ADU demand and underpins the town's identity. Cave proximity does not impose ADU-specific construction restrictions but ADU site selection should avoid surface karst features near the cave system. - 1892-03-04 — Town of Grottoes incorporated by Virginia General Assembly (town-charter)
The General Assembly chartered Grottoes on March 4, 1892, formalizing what had been the Shendun (later Grottoes) settlement on the South River. The town's name derives from the Grand Caverns / Madison Cave system; the railroad-and-cave tourism economy supported early growth.
Effect: Established the town's authority to adopt independent zoning under what is now Va. Code § 15.2-2280 et seq., across the unusual Rockingham / Augusta county-line geography. - 1985-11-04 — November 1985 Election Day Flood - South River through Grottoes (natural-event)
The November 1985 flood produced extraordinary South River stage through Grottoes, inundating the eastern third of the town. Updated FEMA Flood Insurance Rate Maps remapping followed, expanding the mapped Special Flood Hazard Area along the river corridor.
Effect: Grottoes parcels along the South River, Mill Creek, and lower-elevation rear-yard areas are in mapped Zone AE. ADU finished-floor elevation must clear Base Flood Elevation plus Virginia freeboard. Substantial Improvement (50% threshold) review on SFHA parcels. - 2026-04-14 — Virginia SB 531 signed into law (statewide ADU preemption) (state-statute)
SB 531 (2026 General Assembly Regular Session) requires every Virginia locality, effective July 1, 2027, to permit at least one ADU by right on any parcel with an existing single-family dwelling, caps total local permit and zoning fees at $500, and preempts owner-occupancy mandates. Ordinances adopted before January 1, 2026 are grandfathered.
Effect: Grottoes' R-1/R-2 ADU framework will be at least as permissive as SB 531 effective July 1, 2027 (the town already permits ADUs by right in residential districts); the fee cap will reduce the permit-bundle cost from ~$1,560 to $500 (excluding Floodplain Development Permit fees, which are not preempted).
Known issues (2)
- fee-schedule-pending — Approximately $1,060 in permit-fee savings on each by-right ADU built after July 1, 2027 on a non-floodplain Grottoes parcel.
- other — Adds approximately 5-15 days for parcel-county confirmation at pre-application; otherwise the path is comparable to other Rockingham-County-side towns.
Rockingham County — county ADU rules and overlays
County ADU ordinance
Rockingham County regulates accessory dwelling units primarily through accessory-use provisions in its zoning ordinance rather than through a standalone ADU chapter. The county's agricultural (A-1, A-2) and residential (R-1, R-2, RG-1) districts permit one accessory dwelling unit on a qualifying lot subject to minimum lot area, setback, and public-health requirements (well and septic sizing), with the ADU treated as subordinate to the principal dwelling. The county does not operate a Northern-Virginia-style ADU ordinance with an explicit size cap; instead, ADU feasibility is driven primarily by (1) the district's minimum lot area, (2) onsite-sewage capacity under Virginia Department of Health (VDH Central Shenandoah Health District) rules, and (3) the Uniform Statewide Building Code's residential-occupancy requirements. ADU feasibility is materially higher on rural A-1 and A-2 acreage than in the small R-1 residential subdivisions near Harrisonburg, where setback and lot-area minimums often require a Special Use Permit for a second dwelling. Short-term rental is regulated separately under the county's zoning ordinance with a distinct STR classification. Confirm the current accessory-dwelling section text and any by-right vs. Special Use Permit classification with the Rockingham County Department of Community Development before pricing a project.
County regulatory overlays
Rockingham County administers three overlay regimes that bear materially on ADU projects: (1) a Floodplain Overlay District tied to FEMA Special Flood Hazard Areas along the North River, South Fork Shenandoah River, Dry River, Smith Creek, Cooks Creek, and other Shenandoah Valley drainages; (2) Agricultural-Preservation and rural-preservation overlays reflecting the county's strong poultry and livestock economy and the visual character of US 33, US 11, and I-81 corridors plus the Skyline Drive / Shenandoah National Park and George Washington National Forest gateway routes; and (3) a public water-and-sewer service-area framework run by the Harrisonburg-Rockingham Regional Sewer Authority (HRRSA) and the Rockingham County Public Works / Utilities Division that sharply separates ADU feasibility inside vs. outside those service areas. The Massanutten resort area carries its own density and STR-related planning context reflecting its history as a Planned Community / Large-Scale Development. Rockingham County has NO coastal-commission jurisdiction (it is entirely inland, far outside the Chesapeake Bay Preservation Act boundary), NO CalFire-equivalent WUI regulatory overlay (Virginia has no statewide WUI program; the Virginia Department of Forestry coordinates wildfire response without a permit-constraining overlay), NO seismic-retrofit overlay (standard IRC/IBC provisions as adopted in the Virginia Uniform Statewide Building Code govern), and NO FAA Part 150 airport-noise overlay imposed on surrounding parcels (Shenandoah Valley Regional Airport / KSHD sits partly in Rockingham County with commercial service but no Part 150 noise-exposure overlay is in force).
- Rockingham County Floodplain Overlay District
- Rockingham County Water and Sewer Service Area / HRRSA Overlay
- Agricultural-Preservation and Rural-Preservation Context (Poultry Industry, Shenandoah National Park, George Washington National Forest, Conservation Easements)
County permitting (unincorporated parcels)
Rockingham County's Department of Community Development issues ADU building permits for every parcel in the county except those inside the independent city of Harrisonburg (which operates its own building department and zoning ordinance) and, for zoning matters, those inside the Towns of Bridgewater, Broadway, Dayton, Elkton, Grottoes, Mount Crawford, and Timberville where the town has displaced the county code. All unincorporated communities including Penn Laird, McGaheysville, Massanutten, Keezletown, Linville, Singers Glen, Lacey Spring, Fulks Run, Bergton, Cross Keys, and Port Republic route through the county. A typical Rockingham County ADU permit bundle includes: (1) a Zoning Permit from the county Planning and Zoning Division confirming district eligibility, setbacks, and any overlay triggers, (2) a Building Permit with stamped residential plans filed with the Building Inspections Division, (3) Electrical, Plumbing, and Mechanical trade permits, (4) a Virginia Department of Health onsite-sewage / well construction permit from the Central Shenandoah Health District for parcels not served by public water and sewer (the majority of county parcels), (5) a Floodplain Development Permit if any portion of the parcel is within the mapped 100-year floodplain under the county's Floodplain Overlay, and (6) any town-level review if the parcel is inside one of the seven incorporated towns.
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
- 24471
Post Office
- 110 6th St, 24441