Mercer Island Council adopts new residential code

After a nearly year long public process launched by the Mercer Island Planning Commission and City Council, the council adopted updates to the city’s residential development standards, including tree code changes, at its Sept. 19 meeting. A summary of the changes can be found here.

The council reviewed the commission’s recommendations, along with input from the community, during seven meetings between June and September.

The council voted 5-1 to adopt the code. Councilmember Wendy Weiker voted no after proposing some last-minute amendments that would add more flexibility for homeowners, especially those who want to remodel rather than tear down and rebuild. Councilmember Dave Wisenteiner was absent.

Local builders and developers have said that the new building code is one of the most restrictive in the region. The process was initially spurred by concerns from residents about the rapidly changing character of Mercer Island’s neighborhoods.

It has included a substantial effort to reach out to a broad cross-section of the community, using a variety of outreach tools including traditional meetings and public hearings, as well as social media. The city heard from many people in the community, receiving over 475 written comments, according to a press release.

The code amendments adopted by the City Council will place new limits on house size and bulk, increase tree protection, limit construction impacts in neighborhoods and allow for far fewer deviations and variances. The ordinance adopting these regulations will be effective on Oct. 2 and the new provisions will take effect on Nov. 1.

“The updated Residential Development Standards will address concerns from the community by protecting trees, maintaining neighborhood character and ensuring homes are built at a scale that is compatible with their neighborhood,” Mayor Bruce Bassett said in a statement.

Councilmember Dan Grausz said he would look back on the code rewrite as “one of [his] more defining moments on this council.” Councilmember Salim Nice said that one of the best things to arise from the process was that the city hired a long-range planning manager, which it did not have during the similarly extensive and contentious Town Center code rewrite.

City staff are now working to prepare a package of outreach materials to educate the public on the contents of the new provisions, and plan to hold information sessions in the coming weeks to educate permit applicants, builders, architects and residents of the new code provisions. Staff will continue this ongoing education effort in the coming months to ensure all residents and builders understand the provisions of the code.

Deputy Mayor Debbie Bertlin said she will be looking for the council to exhibit an “adaptive management approach,” and try to correct unintended consequences promptly if they arise. Councilmember Benson Wong reiterated that the council should be “nimble” in administering the new code.

Learn more about the process at

Summary of key dates

Sept. 20 – Oct. 31: Focused outreach to permit applicants, builders, architects

Oct. 2: Effective date of ordinance

Nov. 1: New code provisions go into effect

November dates tbd: Information sessions for building professionals (architects, builders, arborists, etc) on the new code provisions

Ongoing: Education for DSG customers and residents about new residential code provisions