What Can You Build on AR-1 Land in Loudoun County?

Western Loudoun County's rolling hills, open acreage, and historic farm corridors are among the most sought-after rural landscapes in Northern Virginia. Much of that land carries one designation: AR-1, or Agricultural Rural-1 zoning.

If you own AR-1 land — or are evaluating a parcel — this zoning district shapes nearly every decision you'll make. How large a home you can build. Whether you can add a guest cottage. Whether your winery or event barn is permitted. Whether you can subdivide.

Most landowners don't get a clear picture of AR-1 rules until they're well into the process — and by then, surprises are expensive. This guide translates the Loudoun County Zoning Ordinance (adopted December 2023) into practical terms for anyone planning to build.

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What Is AR-1 Zoning?

AR-1 — Agricultural Rural-1 — is one of Loudoun County's core rural zoning districts. According to Loudoun County's official GIS metadata, AR-1 is designed for "rural business and residential uses" and sits within the Rural North Place Type as defined in the County's General Plan.

AR-1 is distinct from neighboring designations:

AR-1 generally occupies the northern and western portions of rural Loudoun — the Horse Country corridor through Middleburg, Bluemont, Round Hill, and Purcellville. It's the district where many of the county's estates, equestrian farms, and working vineyards are located.

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Density: How Many Buildings Are Actually Allowed?

This is where landowners often get their first surprise. AR-1 density depends on which subdivision option you use, and each option carries different rules on lot size, open space preservation, and cluster requirements.

Base Density Division

The most straightforward option: 1 lot per 20 acres, with a minimum lot size of 20 acres. If you own 40 acres, you can create two 20-acre lots. If you own 100 acres, you can create up to five lots. This option preserves the rural character of large tracts and is the default approach for legacy estate properties.

Principal/Subordinate Subdivision

Allows 1 lot per 10 acres, doubling the density of the base option. A principal lot retains the farm or estate character, while subordinate lots can be created for additional homes or family members. This path works for multigenerational estate planning.

Cluster Subdivision

The highest-density option at 1 lot per 5 acres, though this comes with requirements: approximately 70% of the total land area must be designated as rural economy lots (15 acres or larger) and/or common open space. The tradeoff is smaller individual lot sizes — as small as roughly half an acre — within the cluster, while most of the acreage remains undeveloped.

Practical implication: A 100-acre AR-1 parcel can yield anywhere from 5 lots (base density) to 20 lots (cluster). Which path you choose shapes your entire site plan, infrastructure strategy, and resale potential.

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What Can You Build? Permitted Uses on AR-1 Land

The AR-1 permitted use list is extensive — as the Friends of the Blue Ridge Mountains noted in their analysis of Loudoun's zoning rewrite, the AR-1 use list runs to roughly seven and a half pages. Here are the categories most relevant to estate and rural builders:

1. Primary Residence (Single-Family Detached)

You can build a custom single-family home on any AR-1 lot that meets the applicable minimum lot size. For base density lots, that's 20 acres. There is no square footage cap on the primary residence, though setbacks and other site conditions apply.

Hearthstone regularly builds estate homes in the $350–$600+/sq ft range on AR-1 parcels. Sites in this district often require substantial infrastructure investment — well, septic, driveway access, and site grading — before construction begins.

2. Accessory Dwellings (Guest Cottages, In-Law Suites)

AR-1 gives landowners meaningful flexibility for secondary residences:

*Example:* A 70-acre AR-1 parcel (20 acres + 50 additional acres) could accommodate up to 3 accessory dwellings in addition to the primary residence — a meaningful opportunity for guest cottages, farm manager housing, or rental income properties.

All accessory dwellings on individual sewage disposal systems require Health Department approval. Size limits apply: on rural lots, an accessory dwelling cannot exceed 70% of the gross floor area of the principal structure or 2,500 square feet, whichever is less.

→ See also: [Hearthstone's estate home and guest cottage services](https://hearthstonedesignbuild.com/services)

3. Agricultural Structures: Barns, Equipment Buildings, and Equestrian Facilities

Agricultural structures are among the most permissive uses on AR-1 land. A Farm Building or Structure Application is required for all agricultural structures regardless of size, per Loudoun County's official permitting guidance. Agricultural structures not subject to the Virginia Uniform Statewide Building Code (VUSBC) require only a county zoning permit fee of $165.

Common agricultural structures permitted on AR-1 include:

Post-frame barns and heavy timber frame agricultural structures are both well-suited to this district. Hearthstone's agricultural buildings range from $100–$250/sq ft depending on finish level and intended use.

4. Farm Wineries and Farm Breweries

This is one of AR-1's most strategically valuable permissions for landowners interested in agritourism or hospitality development.

Under Virginia law (Virginia Code § 15.2-2288.3) and Loudoun County's zoning ordinance, farm wineries and farm breweries are permitted on AR-1 zoned land. Farm breweries can open on land zoned Agricultural Rural (AR-1, AR-2, A-3, or A-10), per Troxell Leigh Law, subject to acreage requirements and private water and septic constraints.

Important note: The Loudoun County Board of Supervisors initiated a review of western Loudoun rural uses and standards in September 2024. This process — projected to conclude in early 2027 — is reviewing how farm wineries, breweries, distilleries, and agritourism events are regulated. Rules may evolve. See the County's project page for updates.

5. Agritourism Event Structures

Virginia's 2022 Agritourism Event Structure law (Virginia Code § 36-98.4) created a dedicated regulatory pathway for event buildings on farm properties. On qualifying AR-1 parcels, event barns, pavilions, and hospitality venues associated with agricultural operations can be constructed under this framework.

Loudoun County has 40+ active wineries and is the heart of Virginia wine country — agritourism construction demand in this district is active and growing.

6. Home Occupations

Limited commercial use of a residential structure is permitted as a home occupation, subject to restrictions on traffic, signage, and number of employees working on-site.

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What You Cannot Build (Without Additional Approvals)

AR-1 is rural zoning — it isn't designed for commercial or high-density development. The following require Special Exception approval or are not permitted:

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The Infrastructure Reality: Site Costs on AR-1 Land

The single most important thing landowners underestimate on AR-1 parcels is site infrastructure cost. Unlike suburban lots served by public water and sewer, AR-1 properties typically require:

Well: A Health Permit from the Virginia Department of Health is required before drilling begins. The well location must comply with setback requirements from sewage systems, property lines, and agricultural operations. (Loudoun County well permitting guidance)

Septic system: A Sewage Disposal Permit is required before any septic system is installed. This requires a site and soil evaluation (perc test) conducted by a licensed Onsite Soil Evaluator (OSE) or Professional Engineer. Health Department approval must be obtained before Loudoun County will issue a building permit.

Driveway and access: Rural parcels frequently require significant driveway installation — grading, gravel, culverts — before construction equipment can reach the build site. On steep terrain, this cost compounds quickly.

Site grading: Many western Loudoun properties involve significant topographic variation. Site grading, retaining walls, and drainage management are real line items on the budget.

Typical site cost range on AR-1 parcels: $150,000–$400,000+, depending on terrain, infrastructure complexity, and distance from the road. This range is not unusual — it's the baseline for rural development in Loudoun County.

This is why Hearthstone begins every project with a preconstruction feasibility phase: to identify site constraints, confirm septic/well viability, and align the construction budget with the real cost of the land before design begins. Discovering a septic setback conflict at the permit stage — or realizing the driveway needs 800 feet of cut-and-fill — is the kind of problem that costs months and hundreds of thousands of dollars when caught late.

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Setbacks: How Close Can You Build to Property Lines?

Setback requirements for AR-1 structures are governed by Table 2.04.01-1 of the Zoning Ordinance, with flexibility available through the county's Determination process (Section 10.02). Because AR-1 parcels tend to be large and not flanked by dense neighbors, setbacks are generally less constraining than in suburban districts — but they matter for multi-structure planning, especially when siting barns, guest houses, and event facilities relative to each other and to property lines.

Contact Loudoun County's Building and Development department (703-777-0220) or submit a Setback Request through the LandMARC system for a property-specific determination.

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Working the Zoning Before You Design

The most common and costly mistake on AR-1 land: starting design before completing zoning and site feasibility.

The design-build sequence on rural properties should always follow this order:

1. Confirm zoning and permitted uses for your intended program

2. Conduct septic and well feasibility (Health Department)

3. Assess site grading, access, and utility requirements

4. Establish realistic infrastructure budget

5. Begin design aligned to actual site constraints

6. Submit for permits

Attempting to reverse this sequence — designing a custom estate home and then discovering the property won't support a septic system in the intended location — is how projects stall for 12 months or never move forward at all.

Hearthstone's preconstruction phase ($7,500–$12,500) is specifically designed to compress this process, identify problems on paper before they become field problems, and give landowners a realistic, site-specific roadmap before any significant design fees are spent.

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The Bottom Line for AR-1 Landowners

AR-1 zoning offers genuine building flexibility for estate homes, agricultural structures, accessory dwellings, farm wineries, and agritourism facilities. But the rules are layered, the density logic is counterintuitive, and the infrastructure costs are real.

The landowners who build successfully on AR-1 land are the ones who understand the rules — and who work with a builder who has navigated this specific terrain before.

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Ready to Understand What's Buildable on Your Land?

If you own AR-1 land in Loudoun County — or are evaluating a purchase — a zoning strategy review is the right first step. Hearthstone Design Build offers land and zoning strategy consultations for landowners in Loudoun, Fauquier, Clarke, and Albemarle Counties.

[Request a land and zoning strategy review →](https://hearthstonedesignbuild.com/contact)

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Frequently Asked Questions

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Internal linking suggestions: Link to Hearthstone's Agricultural Buildings service page, the Timber Frame Construction service page, and any future articles on septic/well planning for rural builds and building on agricultural land in Loudoun County.

Sources: [Loudoun County Zoning Ordinance (December 2023)](https://www.loudoun.gov/zoningordinance) | [Loudoun County GIS Zoning Metadata](https://logis.loudoun.gov/metadata/Zoning_12_12_2023.html) | [Loudoun County Sheds and Agricultural Structures Permitting](https://www.loudoun.gov/5383/Sheds-and-Agricultural-Structures) | [Loudoun County Well & Septic Permits](https://www.loudoun.gov/1200/Well-Septic-Permits) | [Western Loudoun Rural Uses and Standards Review](https://www.loudoun.gov/6088/Western-Loudoun-Rural-Uses-and-Standards) | [Troxell Leigh Law — Winery/Brewery Zoning Guide](https://tllawpc.com/what-do-i-need-to-open-a-brewery-or-winery-on-my-property/)