The Complete Guide to ADU Regulations in 2025

<h2>Understanding ADU Regulations</h2><p>Accessory Dwelling Units (ADUs) have become one of the most talked-about solutions to the housing crisis in America. As cities and states grapple with housing shortages, ADU regulations have evolved rapidly, creating both opportunities and challenges for homeowners and builders alike.</p><h3>California: Leading the Way</h3><p>California continues to lead the nation in ADU-friendly legislation. Recent updates to state law have further streamlined the permitting process, reduced fees, and expanded where ADUs can be built. Key provisions include:</p><ul><li>Ministerial approval process (no discretionary review)</li><li>Reduced setback requirements for conversions</li><li>No parking requirements for ADUs near transit</li><li>Owner-occupancy requirements largely eliminated</li></ul><h3>Washington State</h3><p>Washington has made significant strides in ADU legislation, particularly in urban areas. The state now requires cities to allow at least two ADUs per lot in most residential zones.</p><h3>Oregon</h3><p>Oregon was among the first states to mandate ADU allowances statewide, and continues to refine its approach with reduced barriers to construction.</p><h3>Key Takeaways</h3><p>While regulations vary significantly by state and municipality, the overall trend is clear: ADUs are becoming easier to build across the country. Contractors and homeowners should stay informed about local requirements and work with experienced professionals who understand the permitting landscape.</p>