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Hunts Point ADU and detached ADU rules

Hunts Point ADU and DADU rules for waterfront and inland lots

Hunts Point's published code allows one ADU, even though Washington's two-ADU statute applies to the Town. Beyond that unresolved conflict, waterfront status, the R-40/R-20/R-20A zone, shoreline rules, critical areas, GFA, sewer, and fire access can completely change the DADU answer.

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 local code allows one attached or detached ADU: up to 1,500 square feet in R-40 and 1,250 square feet in R-20 or R-20A Flexible. State law appears to require a second ADU option. A parcel-level design must then use the correct zone's GFA, waterfront or inland yards, grade-based height envelope, shoreline, and critical-area rules.

1 local / 2 statePublished unit-count conflictObtain a written interpretation for a second ADU.
1,250–1,500Maximum square feetThe applicable cap depends on the zone.
No STRShort-term ADU rentalHPMC 18.20.140 prohibits short-term rentals.

What is allowed on one lot

The published R-40, R-20, R-20A, and general zoning provisions allow a single-family dwelling plus one attached or detached ADU. That one-unit limit is narrower than RCW 36.70A.681 and appears subject to preemption. Ask the Town to state in writing how it will permit the second ADU required by state law.

  • 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 state baseline, subject to written Town confirmation.
  • Conversion of an existing structure, including a qualifying nonconforming footprint, subject to safety review.

Official sources: HPMC Chapter 18.20: general zoning regulations · HPMC Chapter 18.31: R-40 · HPMC Chapter 18.36: R-20 · HPMC Chapter 18.38: R-20A Flexible · RCW 36.70A.681: limits on local ADU regulation

Size, height, setbacks, and site capacity

Maximum size
The maximum is 1,500 square feet in R-40 and 1,250 square feet in R-20 and R-20A Flexible.
Height
Height is not a single DADU number. R-40 uses side-setback planes and an overall original-/finished-grade envelope, generally reaching 30 feet above original reference grade or 36 feet above finished contact grade. R-20 and R-20A generally use 26/32 feet, with a potential 30/36-foot path when the enhanced addressed-side setback is met.
Setbacks
Use the zone and waterfront status. R-40 side yards equal 10 percent of lot width with a 10-foot minimum; waterfront/stringline and inland front/rear rules differ. R-20 generally uses a 40-foot inland front, 35-foot principal rear, and 10-foot sides; R-20A Flexible generally uses 30-foot front, 10-foot rear, and 10-foot sides. Get a written interpretation of whether a DADU receives any accessory-structure rear-yard or GFA treatment.
FAR, lot coverage, or impervious area
R-40 uses a graduated GFA formula beginning at 25 percent on the first 20,000 square feet. R-20 generally allows the greater of 5,200 square feet or 25 percent FAR, while R-20A uses its own lot-area formula. The ADU, garages/accessory buildings, lot coverage, shoreline vegetation, and site improvements must be calculated under the correct district provisions.

Official sources: HPMC Chapter 18.31: R-40 · HPMC Chapter 18.36: R-20 · HPMC Chapter 18.38: R-20A Flexible

Parking, occupancy, renting, and separate sale

Parking
The zone text nominally asks for two additional spaces and contains confusing cross-references. Washington's limits control: no ADU parking within a half-mile walking distance of major transit, and no more than two spaces per ADU on these larger lots. Have the Town confirm the exact existing-space credit and configuration.
Owner occupancy
No operative owner-occupancy requirement was identified, and state law prohibits one.
Short-term rental
Hunts Point prohibits short-term rentals.
Separate sale
State law protects separate condominium conveyance solely from an ADU-based prohibition. A fee-simple division, unit lot, or condominium project requires separate land-use and title work.

Official sources: HPMC Chapter 18.20: general zoning regulations · RCW 36.70A.681: limits on local ADU regulation

Utilities, fire access, and the permit path

Occupied structures must connect to sanitary sewer, and utilities are generally underground. Building/fire, shoreline, critical-area, tree/vegetation, drainage, access, and site-development review remain part of the permit path.

  1. Ask for a written Town interpretation if two ADUs or an ambiguous accessory-structure setback/GFA provision is part of the concept.
  2. Determine the exact zone, waterfront status, shoreline jurisdiction, lot dimensions, original grade, and applicable GFA formula.
  3. Overlay critical areas/buffers, shoreline setbacks and vegetation, sewer, fire access, trees, drainage, easements, parking, and construction staging.
  4. Submit the building and all site-development, shoreline, critical-area, utility, tree, fire, and right-of-way applications with coordinated professional studies.
  5. Budget professional review, utility and recording costs, and any access or sprinkler mitigation before finalizing the project.

Official sources: HPMC Chapter 18.20: general zoning regulations · Hunts Point Municipal Code

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.

  • A second ADU remains a state/local-code conflict requiring written Town direction.
  • A large share of Hunts Point parcels are within 200 feet of ordinary high water, where the Shoreline Master Program adds review and vegetation/site constraints.
  • Wetlands, floodplain, habitat, steep slopes, geologic and earthquake hazards, and aquifer concerns can require reports, buffers, avoidance, and mitigation.
  • R-40, R-20, and R-20A use materially different setbacks, GFA, and height envelopes; a citywide rectangle is unreliable.
  • Long private lanes, waterfront access, hydrant/water supply, sewer routing, and fire-apparatus constraints can be decisive.

Official sources: Hunts Point Ordinance 588: critical areas · HPMC Chapter 18.20: general zoning regulations

Prepared for a future address check

What a reliable DADU feasibility screen must verify

Hunts Point needs a zone- and waterfront-aware engine, not a generic DADU setback. The screen must calculate the applicable GFA and height planes, map shoreline/critical areas, and carry manual-review flags for the second ADU and ambiguous accessory-structure treatment.

Jurisdiction and zoning

Confirm the address is actually governed by Hunts 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.

No automated result should resolve the state/local unit-count conflict, stringline, shoreline ordinary-high-water line, original reference grade, or R-20/R-20A DADU classification without written or surveyed evidence.

Do not rely on the older rule

The one-ADU ceiling is still embedded in the published zoning code. Washington's ADU law applies to fully planning towns without a middle-housing population threshold, so Hunts Point's smaller size does not itself preserve a one-unit limit.

Primary sources

Official Hunts 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.

HPMC Chapter 18.20: general zoning regulationsCurrent general ADU, rental, shoreline, utility, critical-area, and permit provisions.HPMC Chapter 18.31: R-40R-40 ADU size, GFA, setbacks, waterfront, and height-envelope rules.HPMC Chapter 18.36: R-20R-20 ADU size, GFA, setbacks, and height rules.HPMC Chapter 18.38: R-20A FlexibleR-20A ADU size, GFA, setbacks, and height rules.Hunts Point Ordinance 588: critical areasCurrent wetland, habitat, flood, geologic, earthquake, and aquifer provisions effective in 2026.Hunts Point Municipal CodeCurrent sewer, building, fire, permit, fee, and related chapters.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 Hunts 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.