Issaquah adopts middle‑housing and ADU code updates to meet state law while preserving critical areas protections

The Issaquah City Council on May 19 adopted a set of ordinances to bring local code into compliance with recent Washington state middle‑housing and accessory dwelling unit legislation while retaining critical areas protections and local design standards.

The package — four ordinances amending Issaquah Municipal Code Title 18 and the city’s street standards — had been developed with public outreach, Planning Policy Commission (PPC) review and Planning, Development and Environment committee input. Valerie Porter, an associate planner, told the council the code changes implement state House Bill 1110 (as amended) and House Bill 1337 for ADUs and reflect later clarifications on what constitutes a major transit stop.

Why it matters: the ordinance package expands permitted housing types in single‑family zones (duplex, triplex, fourplex, townhomes, cottage/courtyard and stacked flats) and sets lot‑density and permitting rules that aim to streamline smaller‑scale housing while protecting environmentally constrained lots and local neighborhood character.

Key points adopted: • Lot density and permitting — Middle housing is defined to include building types with up to four units for streamlined administrative review; in general two dwelling units will be allowed per lot, and four units will be allowed on lots within a quarter‑mile walking distance of a major transit stop (the city clarified it currently has no qualifying major transit stop). Middle‑housing projects are generally exempt from a land‑use permit and will be reviewed by building permit only; existing frontage‑improvement requirements are waived for middle housing built on existing lots. • ADUs — The code allows up to two ADUs on a lot with a detached single‑family dwelling in several configurations; ADUs count toward lot density. Owner‑occupancy requirements were removed to comply with state law. • Affordability and sizing — For units designated as affordable, ownership units are defined at 80% of area median income (AMI) and rental affordable units at 60% AMI. PPC retained a 1,000‑square‑foot maximum for ADUs (a size the commission equated with a two‑bedroom unit). • Design and open space — Design standards from Old Town were adapted citywide for new building types; cottage and courtyard housing require at least 20% of the lot be set aside for open space. • Parking and frontage — The parking table was adjusted so detached single‑family homes with a garage plus driveway can use driveway stalls; street‑frontage rules were amended so middle housing on existing lots is not forced to build new frontage improvements.

Porter said PPC unanimously approved the package on March 27; Councilmember Hall, who chaired PDE during the process, said the committee took a deliberate approach, sought public input and recommended monitoring several items over time (lot density, ADU size and impact‑fee impacts).

Public comment during the meeting included Old Town residents urging preservation of neighborhood character and suggesting ADUs and modest increases in density as a gentler way to add housing. The Downtown Issaquah Association noted volunteer efforts and events that support economic vitality in the city core.

Council members who spoke supported the package while acknowledging tradeoffs: smaller middle‑housing units are likely to be the most feasible given local lot sizes and impervious‑surface limits; the council also signaled interest in exploring ways to leverage local funding (for example IHIP) to catalyze affordable middle‑housing projects.

The council adopted the ordinances (packet listed as Ordinance Nos. 3091–3094) with an implementation date adjusted in the clerk’s office to the minimum allowable effective date (May 27). The vote was unanimous.