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Yarrow Point ADU and detached ADU rules

Yarrow Point ADU and DADU rules, including the state-law conflict

Yarrow Point's 2025 ordinance still allows only one ADU and appears to confuse the Town's middle-housing population tier with Washington's separate two-ADU mandate. The detached-unit fit itself is also unusually sensitive to shoreline setbacks, protected trees, private lanes, critical areas, and a potentially significant garage interpretation.

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 rule allows one attached or detached ADU from 220 square feet up to the lesser of 6 percent of lot area or 1,000 square feet. State law appears to require a second ADU option. A new DADU must then satisfy the Town's 25-foot street/private-lane yards, 10-foot interior yards, 20-foot building separation, height, coverage, shoreline, tree, and utility rules. It may also face a disputed two-car-garage requirement.

1 local / 2 statePublished unit-count conflictThe Town's middle-housing tier does not create an ADU population exemption.
6% or 1,000Maximum ADU sizeUse the lesser number; the minimum is 220 square feet.
30% / 60%Structural / imperviousBoth limits apply before trees and shoreline constraints.

What is allowed on one lot

YPMC 17.16.170 publishes a one-ADU limit on a legal buildable lot with an existing single-family dwelling and no more than one existing unit. RCW 36.70A.681 requires fully planning towns to allow at least two ADUs and has no middle-housing population-tier exception. A second unit therefore needs a written Town interpretation of the state preemption and permit path.

  • One attached or internal ADU under the published local text.
  • One detached ADU under the published local text.
  • A second attached or detached ADU under the statewide baseline, subject to written Town confirmation.
  • Conversion of an existing structure, including a qualifying nonconforming structure, subject to health and safety review.

Official sources: Yarrow Point Ordinance 769 · RCW 36.70A.681: limits on local ADU regulation

Size, height, setbacks, and site capacity

Maximum size
An ADU must contain at least 220 square feet and no more than the lesser of 6 percent of lot area or 1,000 square feet. Garage area is excluded.
Height
The residential height envelope is the lesser of 25 feet above original grade or 31 feet above finished grade.
Setbacks
The base yards are 50 feet from the shoreline, 25 feet from a public right-of-way, 25 feet from a serving private lane, and generally 10 feet from other private property lines, panhandles, and non-serving lanes. Detached dwelling structures require 20 feet of separation. Critical areas, trees, easements, and fire access can require more.
FAR, lot coverage, or impervious area
Structural coverage is limited to 30 percent and impervious coverage to 60 percent. No separate residential FAR was identified. The house, DADU, garage, parking, walkways, utilities, tree protection, shoreline vegetation, and drainage must fit together.

Official sources: Yarrow Point Ordinance 769 · Yarrow Point Municipal Code

Parking, occupancy, renting, and separate sale

Parking
The code contains both general parking language and a rule that generally requires each dwelling unit to include a two-car garage; an ADU conversion with no added structural area is exempt from that garage rule. The Town may try to apply a two-car garage to a new DADU, but Washington's parking caps and half-mile transit exception still control. Obtain a written interpretation before designing the building around a garage.
Owner occupancy
No current owner-occupancy requirement was identified, and state law prohibits one.
Short-term rental
Council materials showed short-term-rental rules under discussion in 2026, but no adopted ADU-specific prohibition was identified through the review date. Confirm the current ordinance status and private restrictions before planning short stays.
Separate sale
State law prevents a condominium-sale prohibition based only on prior ADU status. A unit-lot, condominium, or fee-simple division requires separate Town and title review.

Official sources: Yarrow Point Ordinance 769 · RCW 36.70A.681: limits on local ADU regulation

Utilities, fire access, and the permit path

Bellevue water and sewer availability must be documented. New utilities are generally underground, and each right-of-way excavation or connection needs Public Works approval. Bellevue Fire reviews access and water supply.

  1. Request written Town interpretations for a second ADU and for any two-car-garage requirement on a new detached unit.
  2. Confirm legal-lot status, zone, shoreline jurisdiction, critical areas, private-lane classification, setbacks, 20-foot building separation, grade, coverage, and existing units.
  3. Inventory significant and heritage trees with root-protection zones, then place utilities, fire access, parking, and construction staging around them.
  4. Complete the mandatory preapplication conference for projects over $50,000 and identify building, site-development, tree, shoreline, critical-area, utility, and right-of-way permits.
  5. Budget plan review, consultants, construction-vehicle and street deposits, utilities, and inspections before choosing a plan.

Official sources: Yarrow Point permits and utility requirements · Yarrow Point Public Works permits · Yarrow Point permit fees

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 local one-ADU limit appears preempted, but the second-unit workflow is unresolved and needs written Town direction.
  • The two-car-garage language could dramatically enlarge a new DADU and consume structural/impervious capacity; do not assume the interpretation.
  • A 50-foot shoreline yard and shoreline review can control waterfront parcels.
  • Wetlands, geologic hazards, flood areas, streams, habitat, and buffers use approximate mapping and may require field studies.
  • Significant and heritage trees, critical root zones, replacement, mitigation, and bonding can eliminate an apparent backyard footprint.

Official sources: Yarrow Point critical areas · Yarrow Point Ordinance 783 tree update · Yarrow Point Ordinance 769

Prepared for a future address check

What a reliable DADU feasibility screen must verify

Yarrow Point's engine must combine the lot-percentage size formula, lane/shoreline/inter-building setbacks, structural and impervious coverage, original grade, trees, critical areas, utilities, and fire access, with manual flags for the second ADU and garage interpretation.

Jurisdiction and zoning

Confirm the address is actually governed by Yarrow Point 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.

The tool should not resolve the one-versus-two-ADU conflict, the two-car-garage rule, legal undersized-lot status, shoreline ordinary-high-water line, or significant/heritage-tree impacts without written or professional evidence.

Do not rely on the older rule

The Town's published position appears to use its Tier 3 middle-housing population category to justify one ADU. RCW 36.70A.635 uses population tiers for middle housing; the separate RCW 36.70A.681 two-ADU mandate applies to fully planning towns without that population threshold.

Primary sources

Official Yarrow Point 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.

Yarrow Point Ordinance 769The Town's adopted 2025 ADU, middle-housing, dimension, parking, conversion, and application amendments (packet pages 70–93).Yarrow Point Municipal CodeCurrent codified zoning, building, shoreline, parking, utility, and permit chapters.Yarrow Point permits and utility requirementsCurrent preapplication, electronic submission, fire, utility, and permit-process guidance.Yarrow Point Public Works permitsRight-of-way, utility excavation, access, and Public Works approvals.Yarrow Point critical areasCurrent maps, study expectations, ordinance links, and buffer context.Yarrow Point Ordinance 783 tree updateOfficial packet containing the adopted significant/heritage-tree, root-protection, replacement, mitigation, and bonding update.Yarrow Point permit feesCurrent fee resolution, deposits, consultant, and utility-charge links.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 Yarrow Point 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.