City Building Permits

Mercer Island, WA Building Permit Guide

How to apply for a building permit in Mercer Island, Washington. Permit authority, application steps, fees, and inspection requirements.

Washington King County Updated March 2026

Permit Authority

All properties within the incorporated City of Mercer Island.

Department: Community Planning & Development (CPD) - Building Team
Phone: 206-275-7605
Email: epermit.tech@mercerisland.gov
Website: https://www.mercerisland.gov/cpd/page/permit-types

Online Permit Portal

Open MyBuildingPermit.com

Platform: MyBuildingPermit.com • Account required: Yes • Submission: Online only

Additional resources:

Permit Types

Application Process

Access MyBuildingPermit.com
Create account
Select Mercer Island as jurisdiction
Complete online application forms
Upload PDF plans to submittal portal
Pay fees online
City staff reviews application
Receive electronic permit upon approval

Typical processing time: Varies by permit type.

Source: Community Planning & Development (CPD) - Building Team

General Requirements

A building permit is required for most construction within the City of Mercer Island.

Required Documents

Completed permit application
Site plan
Construction plans (PDF format)
Architectural plans
Mechanical/plumbing plans

Permit validity: Varies by permit type.
Building code: 2021 Washington State Building Code (with local administrative provisions aligned to MyBuildingPermit regional model code)
Contractor requirements: Contractors must hold a valid Washington State L&I registration.

Fees

Payment note: Online payment through MyBuildingPermit

Fees change. Verify current amounts at the official fee schedule (effective Current).

Work That Does NOT Require a Permit

One-story detached accessory structures under 200 sq ft
Decks under 30 inches above grade
Fences under 6 feet in height
Retaining walls under 4 feet

Important: Mercer Island has solar-friendly policies. Verify exemptions before proceeding.

Inspections

How to Schedule

MyBuildingPermit.com (online)

Additional Resources

Building code: 2021 Washington State Building Code (with local administrative provisions aligned to MyBuildingPermit regional model code)
Verify contractor license: WA L&I Contractor Lookup
Solar Permits (223+ installations city-wide)
Tree Permits
License lookup guide: Washington Contractor License Requirements
Contract template: Washington Homeowner-Contractor Agreement
Washington hub: Washington Contractor License & Permit Hub

Information on this page was last verified: March 2026. Permit rules and fees change — confirm current requirements directly with the Community Planning & Development (CPD) - Building Team before applying.

Need help with your project?

Navigating permits in Mercer Island can be complicated.

Jaspector connects you with local experts who can review your scope, verify your contractor, and help you understand what permits your project actually needs.

Learn how Jaspector works

Important: This page is an educational resource provided by jaspector.com. It is not legal advice, and it does not substitute for official guidance from the permit authority listed above. Permit requirements, fees, and processes change frequently. Always verify current requirements directly with the issuing department before beginning any construction project. Use of this page does not create an attorney-client relationship. Jaspector assumes no liability for any outcomes arising from reliance on this information.

Other cities in King County

seattle seatac kenmore issaquah

View all King County jurisdictions →