Senate Bill 5747 reenacts and amends existing state building code law and adds new sections to chapters 19.27 and 19.27A RCW. It permits cities and counties to enforce any of the last four iterations of the state building code or energy code, or the current international model codes, for qualifying affordable housing projects. The bill explicitly allows affordable housing projects that meet the criteria in RCW 84.14.020(1)(a)(ii)(B) to be constructed, altered, or repaired under those earlier building code or energy code standards. The bill also reenacts and amends RCW 19.27.015 and amends RCW 19.27A.080 to include a set of definitions and standards used throughout the chapter. Key defined terms include affordable housing (rental housing with housing costs at or below 30% of household monthly income, and owner-occupied housing within means of lowor moderate-income households), lowand moderate-income households (80% or less of local median income), multifamily residential building, residential and commercial building permits, model codes and model code organizations, and technical definitions related to portable oil-fueled heaters and their permitted use and approval. The bill names affected entities such as cities and counties, the unspecified council responsible for building code adoption, model code organizations, fire chiefs, and suppliers. Legally, this is a procedural and statutory change: it creates new statutory sections and amends and reenacts existing provisions to authorize the use of prior code iterations for certain affordable housing projects. It does not create new crimes or change criminal penalties. Important implementation details are not included in the extracted text: the specific council referenced is not named, the exact four prior code iterations (editions or years) are not identified, the qualifying criteria in RCW 84.14.020(1)(a)(ii)(B) are not described here, and the editions of the "current international" model codes are not specified.

If enacted, the bill gives cities and counties the explicit option to apply any of the last four versions of the state building and energy codes (or the current international model codes) when permitting affordable housing projects that meet the referenced tax/qualification rules, which is likely to lower construction costs and speed approvals for developers, nonprofit builders, and housing authorities working to create units that cost tenants no more than 30% of household income or serve owners earning 80% or less of area median income. Local governments gain flexibility and could more quickly approve projects, while builders and suppliers may see reduced compliance costs; the likely trade-off is that some projects built to older code editions could have lower energy efficiency or different safety standards than newer-code projects. The bill also clarifies appliance and heater rules that affect suppliers, retailers, fire chiefs, and building owners: portable oil-fueled heaters must be listed to standards like Underwriters Laboratories, suppliers must certify compliance to the authority having jurisdiction, and use in certain occupancies requires a fire chief’s permit, creating clearer supplier certification and local permit responsibilities and some added administrative oversight. Key details left open here include which exact four code iterations qualify, the identity/authority of the “council,” and the specific qualifying criteria in RCW 84.14.020 referenced by the bill.