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How to apply to change/alter a landmark property

Learn about the process for applying to alter a historic property in unincorporated King County.

What is a Certificate of Appropriateness (COA)?

Most renovation or rehabilitation projects on designated King County or City Landmarks will involve going through design review to obtain a COA. The design review process was developed to help guide projects on local historic landmarks and protect them from demolition or destructive alteration. 

Design review should take place in the early stages of planning a project on a landmarked property, as specific actions may be required to protect significant historic features. Typically, a COA must be obtained before a building permit can be issued. In some cases, projects that do not require a building permit may still require a COA. 

Please note that the county or city permitting department will refer projects without COAs back to the Landmarks Commission for review and approval. For smooth project planning and permit reviews, we recommend contacting the landmarks coordinator when first planning a project.

Landmarked properties are also eligible for preservation incentives, which can help offset the cost of some common rehabilitation or repair projects on historic structures, such as roofing, siding, or foundation work.

How to apply for a COA

Applicants and property owners are strongly encouraged to speak with the King County landmarks coordinator before applying for a COA.  

Complete the application

Please read the COA instructions and sample project description carefully before filling out the application. 

COA instructions (300KB)

COA application (440KB)

Submit application

Return completed applications electronically to: 

Application deadlines

There are three different review levels for project applications. Some small projects (Type I) can be administratively reviewed by HPP staff. These applications can be submitted at any time and are reviewed within 10 days of receipt. 

Type II (alteration or new construction) and Type III (relocation or demolition) project reviews involve two meetings over a 30-day period. The first review meeting is held on the 2nd Thursday of the month with the Design Review Committee (DRC). The second review meeting is held on the 4th Thursday of the month with the Landmarks Commission. 

Complete Type II and Type III COA applications must be received by 5pm on the 1st Thursday of the month to be scheduled on that month’s agenda. 

Contact the landmarks coordinator to determine what level of review would be required for your project and for additional guidance on the design review process.