Codes, Design Criteria & Research

The 2021 CODE UPDATES ARE EFFECTIVE MARCH 15, 2024

Effective MARCH 15, 2024. Washington statutes mandated all jurisdictions in the state adopt and enforce the following updated Construction Code editions as they were adopted and amended by the State of Washington.

Click here to see 2018 Cycle.

2021 Code Cycle
2021	International Building Code (IBC)
2021	International Residential Code (IRC)
2021	International Mechanical Code (IMC)
2021	International Fuel Gas Code (IFGC)
2021	Uniform Plumbing Code (UPC)
2021	International Fire Code (IFC)
2021	International Existing Building Code
2021	International Swimming Pool and Spa Code
2021	International Wildland-Urban Interface Code ^{*Implementation of WUI code delayed due to DNR mapping}
.	Washington State Energy Code (WSEC)
.	Washington Cities Electrical Code (WCEC)
.	ICC/ANSI A117.1-17, Accessible and Usable Buildings and Facilities, with statewide and City amendments

_{***Permit applications received on or after March 15, 2024, shall comply with these codes.***}

_{** Codes are adopted with statewide and City amendments.}

Significant Code Changes

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** Click here to see a listing of significant code changes made in 2024. **

Washington State Amendments to the 2021 Construction Codes

Click here to see Washington State amendments to the 2021 Construction Codes.

City Amendments to the 2021 Construction Codes: the local amendments in the Mercer Island City Code including items such as:

When fire sprinklers are required (for larger buildings, for poor water supply, for poor fire access roads, etc)
Administrative provisions (when permits are required, permit expiration and renewal, etc)
Electrical code amendments

2021 Design Criteria Table

Click here for information regarding minimum design criteria for snow loads, wind and seismic forces, climatic, geographic, and more.

Wind Exposure and Minimum Kzt Factors

Click here to view the City map depicting Wind Exposure Classification and minimum K_zt factors (topographic effects) that will not require the submittal of justifying engineering calculations.

Geologically Hazardous Area Maps and Regulations: Development within Geologically Hazardous Areas requires supporting Geotechnical Reports.