The bill aims to create a new category of building codes specifically for "kit homes," which are defined as residential structures made of prefabricated components that are assembled on-site and are 800 square feet or smaller. The legislation recognizes the growing issue of housing affordability for homebuyers of modest means and seeks to address this by establishing regulations that ensure kit homes remain accessible. The bill amends existing law, specifically RCW 19.27.015, to include the definition of kit homes and outlines the responsibilities of the state building code council in developing these new codes.

Additionally, the bill mandates that the state building code council must complete rule-making for the kit home codes by December 31, 2025, ensuring that the costs associated with these homes do not exceed $150 per square foot for the original homebuyer. Any future updates to these codes must also adhere to this cost limitation, adjusted for inflation. The bill emphasizes the urgency of this initiative by declaring it necessary for the immediate preservation of public peace, health, or safety, and it takes effect immediately upon passage.