ADU Pass
Sterling
No County portion
Also in: Loudoun County
ADU Pass helps homeowners in Sterling, No County, Virginia navigate the permit paperwork for building an accessory dwelling unit. This area covers 2 ZIP codes.
Map
ADU details
ADU legality: allowed-with-restrictions
Sterling is one of the largest CDPs in Virginia (population approximately 30,000) and sits in the Dulles Tech Corridor portion of Loudoun County. ADU rules are Loudoun County rules; the County permits ADUs by special use permit (SUP) in some districts and by-right in others. Owner-occupancy and size caps apply. After July 1, 2027, SB531's by-right ADU mandate and $500 fee cap will preempt the SUP requirement for one ADU per single-family lot.
Cost scenarios
| Scenario | Sq ft | Permit | Build | Total |
|---|---|---|---|---|
| minimum | 300 | $2,400 | $144,000 | $146,400 |
| 600 | 600 | $2,800 | $300,000 | $302,800 |
| midpoint | 600 | $2,800 | $300,000 | $302,800 |
| maximum | 900 | $3,000 | $459,000 | $462,000 |
Fee breakdown (as of 2026-05)
Permitting process
Viability (permitted uses)
- Long-term rental: yes Long-term ADU rental is permitted with owner-occupancy of the primary dwelling. Strong demand from Dulles airport and tech-corridor workers makes this the dominant practical use.
- Short-term rental: with-restrictions Loudoun County requires a Short-Term Residential Rental zoning permit. Dulles airport proximity (5 minutes drive) creates layover and business-travel STR demand; STR registration is mandatory.
- Office rental: no ADU must remain a dwelling unit; commercial use is not permitted under Section 5-622.
- Home office: yes Home occupation permitted under Loudoun's home-occupation standards with limits on employee-visit traffic.
- Studio / workshop: yes Personal studio/workshop use is permitted accessory use.
- Agriculture: with-restrictions Most of Sterling is residential PD-H4 or R-x; agriculture limited. JLMA-adjacent parcels permit small-scale ag uses.
- Relative support: yes Family-occupancy ADU is the dominant Sterling use case; aging-parent and adult-child housing drive much of the demand. Owner-occupancy of the primary dwelling is required.
Incentives
Contacts
Utilities
- Water: Loudoun Water (LCSA) · 35d connect · $6,500
- Sewer: Loudoun Water (LCSA) · 35d connect · $7,800
- Electric: NOVEC (Northern Virginia Electric Cooperative) in most of Sterling; Dominion Energy in some pockets near the Dulles airport boundary · 28d connect · $1,900
- Gas: Washington Gas · 42d connect · $1,700
Property values & taxes
Construction timeline
Realistic total: best 8mo · typical 12mo · worst 18mo
Modular pathway inspectors are occasional with modular
Sterling has good module transport access via Route 7 and Route 28; Dulles airport noise overlays and dense HOA-governed subdivisions limit detached-module placement.
Financing
State ADU loans:
Insurance impact
HOA prevalence & preemption
Most Sterling subdivisions (Sterling Park, Countryside, Cascades, Sugarland Run) are HOA-governed with their own ADU restrictions that often prohibit detached ADUs and tightly limit attached. SB531 (2027) does NOT preempt HOA private covenants - HOA restrictions will continue to bind.
Regulatory overlays (1)
- airport-noise-zone
Portions of Sterling fall within the Dulles International Airport (IAD) noise impact zones (Ldn 60-65 and Ldn 65-70 contours), particularly the Sully Plaza and Cascades-adjacent areas. ADU construction in these zones requires additional soundproofing per Loudoun County's airport overlay standards.
Technical envelope (climate & building code)
Climate & energy code
Building code
Amendments:
- Amendment
- Amendment
Contractor market (aggregate)
Legal history (timeline)
Current ordinance: Loudoun County Zoning Ordinance Chapter 1240, Section 5-622 (Accessory Dwelling Unit), adopted 2023-12-12, last amended 2024-XX-XX
- 2003-01-22 — Loudoun County Zoning Ordinance Section 5-622 (Accessory Dwelling Unit) initial adoption framework (county-ordinance)
Loudoun County established a formal accessory dwelling unit framework as part of the comprehensive 2003 Zoning Ordinance overhaul. Section 5-622 sets size, occupancy, and use standards.
Effect: Established the modern ADU regulatory framework that governs Sterling parcels. - 2023-12-12 — Loudoun County 2023 Zoning Ordinance comprehensive rewrite (county-ordinance)
County Board of Supervisors adopted a major Zoning Ordinance rewrite implementing the 2019 Comprehensive Plan; ADU provisions were modernized including expanded districts where ADUs are permitted by right.
Effect: Current operative ADU rules; effective for Sterling parcels after county-wide effective date. - 2026-04-14 — Virginia SB531 signed - statewide by-right ADU mandate (state-law)
Effective July 1, 2027: by-right one ADU per single-family lot statewide, $500 permit-fee cap, January 1, 2026 grandfather clause for stricter ordinances already in force.
Effect: Will preempt Loudoun's SUP requirement for one by-right ADU per single-family lot in Sterling starting July 1, 2027. Loudoun's 2023 ordinance provisions in force on January 1, 2026 are grandfathered for stricter standards on the second ADU.
Known issues (2)
- policy-review — Loudoun County Board is expected to bring forward conforming amendments to Section 5-622 in 2026-2027 to align with SB531 ahead of the July 1, 2027 effective date; rule changes may shift in late 2026.
- other — Acronym collision: in Loudoun, 'ADU' historically refers to Affordable Dwelling Unit (income-restricted housing), not Accessory Dwelling Unit. The County's ADU Manual covers Affordable Dwelling Units; Accessory Dwelling Units are governed by Section 5-622. Applicants frequently confuse the two.
County: no attribution (synthetic bucket)
No county
This city sits in the state's "no county" bucket — its ADU rules derive directly from state law and city ordinance without a county intermediary. No county-level sections apply.
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 Codes
- 20041
- 20167
Post Office
- 150 S Sterling Blvd, 20164
- 45005 Aviation Dr Ste 120, 20166
Locale Names
- Dulles