Accessory Dwelling Units  |  Housing Supply Planning

This guide provides a comprehensive overview of local policy issues related to accessory dwelling units (ADUs) and includes specific recommendations for cities and counties in Washington to help them develop zoning regulations for ADUs. It begins with a discussion of the demographic trends and laws that have been driving demand for ADUs in the state before describing the benefits of ADUs to communities, home owners, and tenants. Then it summarizes regulatory issues and options, with a focus on zoning. The appendices include the state’s model ordinance for ADUs, a summary of select local ADU regulations, and samples of local ADU permits and forms.