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Beaux Arts Village ADU and detached ADU rules

Beaux Arts Village ADU and DADU rules and the unresolved two-unit issue

Beaux Arts Village adopted updated housing rules in 2025, but its published zoning code still says one ADU while Washington law requires fully planning towns to allow at least two. A homeowner considering a second ADU should obtain a written Town interpretation before investing in design.

Reviewed August 14, 2026 against adopted city code and official city guidance

Quick definitions. An accessory dwelling unit (ADU) is a complete additional home on the same property. A detached ADU (DADU) is in its own building. FAR or GFA limits how much enclosed floor area the property may contain.

Bottom line

What the current rules mean

The published local path allows one attached or detached ADU between 400 and 1,250 square feet. A new DADU must also pass the Town's 20-foot front, 10-foot side, and 25-foot rear yards; 30 percent structural coverage; 50 percent total lot coverage; 35 percent GFAR; sewer; tree; and critical-area checks. The local one-ADU ceiling appears narrower than controlling state law.

1 local / 2 statePublished unit-count conflictGet the Town's written interpretation before designing a second ADU.
400–1,250Square feet per local ruleA related garage is excluded from the ADU size calculation.
35% GFARFloor-area ceilingStructural and total lot coverage also apply independently.

What is allowed on one lot

BAVMC 18.10.040 presently states that one attached or detached ADU may accompany a single-family dwelling. RCW 36.70A.681 requires fully planning cities and towns to allow at least two ADUs in specified attached/detached combinations, and conflicting local controls are subject to state preemption after the implementation deadline. Treat a second unit as a mandatory written-interpretation question, not an automatic denial or an automatic permit.

  • One attached or internal ADU under the published local code.
  • One detached ADU under the published local code.
  • A second attached or detached ADU under the statewide rule, subject to written Town confirmation of how the preemption will be administered.
  • Conversion of a lawful existing nonconforming structure when its nonconformity is not enlarged and applicable safety and parking rules are met.

Official sources: Beaux Arts Village Chapter 18.10: zoning · Beaux Arts Village Ordinance 478 · RCW 36.70A.681: limits on local ADU regulation

Size, height, setbacks, and site capacity

Maximum size
The local ADU must contain at least 400 and no more than 1,250 square feet, excluding a related garage.
Height
The general maximum is 30 feet above existing grade. A shed-roof building face adjacent to a property line is limited to 24 feet, and the code contains additional perimeter-face and grade-measurement rules.
Setbacks
The base residential yards are 20 feet from the front, 10 feet from each side, and 25 feet from the rear, measured to the outermost building projection. Critical areas, easements, sewer, trees, and fire or building separation can add constraints.
FAR, lot coverage, or impervious area
Structural coverage is limited to 30 percent, total lot/impervious coverage to 50 percent, and GFAR to 35 percent. The total area of all structures, including garages and accessory buildings, is capped at 7,000 square feet.

Official sources: Beaux Arts Village Chapter 18.10: zoning

Parking, occupancy, renting, and separate sale

Parking
The local text nominally calls for two spaces per ADU but cross-references the current state-style parking limits. Washington law requires no ADU parking within a half-mile walking distance of a major transit stop and caps requirements at one space per ADU on lots below 6,000 square feet and two spaces on larger lots.
Owner occupancy
No local owner-occupancy requirement was identified, and state law prohibits one.
Short-term rental
The zoning code allows rental of a dwelling or ADU without a commercial-activity permit when notice is given to the Town Clerk. No clear ADU-specific short-term-rental prohibition was identified; confirm the intended rental term with the Town and check private restrictions.
Separate sale
State law prevents the Town from prohibiting separate condominium conveyance solely because a unit began as an ADU. A fee-simple land division must separately meet the Town's lot and subdivision rules.

Official sources: Beaux Arts Village Chapter 18.10: zoning · RCW 36.70A.681: limits on local ADU regulation

Utilities, fire access, and the permit path

Every dwelling must connect to the franchised public sewer. Town building, plumbing, mechanical, electrical, fire, grading, tree, and right-of-way requirements apply; Washington L&I issues electrical permits. Utility capacity and connection charges are separate from the zoning allowance.

  1. Ask the Town Planner for a written determination if two ADUs, a lawful undersized lot, or a nonconforming conversion is proposed.
  2. Prepare a survey-based zoning worksheet for setbacks, height, structural coverage, total coverage, GFAR, and the 7,000-square-foot structure cap.
  3. Confirm sewer capacity and routing, fire/building access, trees, critical areas, drainage, and construction staging.
  4. Submit the electronic building application and every related grading, plumbing, mechanical, tree, demolition, or right-of-way permit.
  5. Budget Town-retained consultant review, utility work, recording, and inspections in addition to base permit fees.

Official sources: Beaux Arts Village Building Department and Permit Center · Beaux Arts Village Chapter 18.10: zoning

Rules that can change the answer for one property

A citywide ADU allowance does not prove that a detached unit fits on a particular lot. Resolve these items before buying plans or fixing the DADU location.

  • The second-ADU entitlement needs a written Town interpretation because the published one-unit limit conflicts with the statewide baseline.
  • Wetlands, habitat, floodplain, steep slopes/geologic hazards, and aquifer or wellhead conditions can support denial or require studies and mitigation.
  • A lawful buildable nonconforming lot may have state-law protection even where the local text points to the new-lot minimum; obtain a parcel-specific determination.
  • Tree removal requires a Town permit, and root zones plus sewer or utility trenches can displace the detached footprint.
  • The lot must satisfy three separate capacity calculations: structural coverage, total coverage, and GFAR, plus the absolute structure-area cap.

Official sources: Beaux Arts Village Chapter 18.10: zoning · Beaux Arts Village Building Department and Permit Center

Prepared for a future address check

What a reliable DADU feasibility screen must verify

A future Beaux Arts DADU screen should calculate the Town's unusually layered capacity limits, but it must also carry a manual-review flag for a second ADU and for any lawful substandard lot.

Jurisdiction and zoning

Confirm the address is actually governed by Beaux Arts Village and select the correct base-zone standards.

Existing and proposed units

Count the principal dwelling, existing legal ADUs, middle-housing units, and the proposed attached or detached configuration.

Surveyed parcel geometry

Use legal lot lines, front/rear designation, alleys, access easements, and existing structures rather than a tax-map rectangle.

Capacity calculations

Test the ADU against the rules that apply locally: FAR or GFA, building or lot coverage, impervious or hard surface, and landscaping.

Mapped and field constraints

Screen critical areas and buffers, shorelines, slopes, flood hazards, significant trees, drainage, and recorded easements.

Utilities and emergency access

Verify water, sewer or septic, fire flow, hydrant and apparatus access, power, meters, and trench routes.

Until the local unit-count language is corrected or the Town publishes an interpretation, the tool should show the state/local conflict explicitly and should not label a second ADU either approved or prohibited.

Do not rely on the older rule

The issue is not merely an old handout: the adopted local code itself still publishes a one-ADU ceiling. Washington's separate ADU statute has no small-town population exemption and appears to preempt that narrower limit, but the Town's permit workflow may not yet reflect it.

Primary sources

Official Beaux Arts Village and Washington references

These are the sources used for this guide. Check them again before filing because ordinances, fee schedules, and permit forms can change.

Beaux Arts Village Chapter 18.10: zoningCurrent local ADU, dimensional, coverage, GFAR, parking, rental, sewer, conversion, and critical-area rules.Beaux Arts Village Ordinance 478The Town's June 2025 housing and ADU amendments.Beaux Arts Village Building Department and Permit CenterCurrent application, review, consultant, inspection, and contact information.Beaux Arts Village 2025 housing adoption pageOfficial adoption record and project context.RCW 36.70A.681: limits on local ADU regulationWashington's current baseline for two ADUs, size, height, parking, owner occupancy, conversions, alleys, fees, and critical-area exceptions.

A practical first-pass checklist

  1. 1

    Confirm the parcel is inside Beaux Arts Village city limits and identify its current zone.

  2. 2

    Map the principal home, lot lines, easements, trees, utilities, driveway, critical areas, and buffers on one current survey.

  3. 3

    Test the ADU footprint against setbacks, height, floor-area or coverage limits, hardscape, parking, and construction access.

  4. 4

    Ask the utility providers to confirm water, sewer, power, meter, side-sewer, and capacity requirements before fixing the design.

  5. 5

    Have the city confirm the complete land-use, building, fire, right-of-way, tree, and utility permit list in writing.