Council schedules second readings to renew interim middle-housing, ADU, and unit-lot rules

At its June 2 meeting, the Mercer Island City Council set second readings for two ordinances renewing interim land-use regulations that implement recent state housing laws. The council voted to schedule a June 16 second reading for Ordinance 2605 (middle housing and accessory dwelling unit interim regulations) and for Ordinance 2606 (unit lot subdivisions implementing SB 5258) staff said.

CPD Director Jeff Thomas introduced the items and Senior Planner Molly Magcguire walked the council through the state requirements and what the interim regulations do. Magcguire said the interim rules adopted last year implement the minimums of House Bill 1110 (middle housing) and House Bill 1337 (ADUs) and that the ordinances before the council would renew those interim rules with no changes for up to six months to allow time for a permanent regulatory process.

"These interim regulations expire on June 30th of 2026. So, those regulations must be renewed to maintain compliance with state law," Senior Planner Molly Magcguire said, describing required allowances for multiple middle-housing types, limits on design-review and parking, and the removal of the ADU owner-occupancy requirement.

Magcguire told the council that the city had seen one duplex application and one single-family application proposing two ADUs, plus several pre-application meetings and inquiries. On a roll-call vote, the council approved the motions to schedule second readings; the voting tally for each motion was recorded as unanimous (7-0).

Staff said the renewed interim regulations, if adopted at second reading, would take effect June 30 and expire on December 30, 2026, while staff conduct community engagement and prepare permanent code amendments.