Washington State HB 1337 – July 2025 Update
House Bill 1337, effective July 23, 2025, requires cities and counties – including Pierce County and its municipalities — to allow at least two Accessory Dwelling Units (ADUs) per lot that already permits a single-family home
Here’s a refreshed breakdown for Pierce County residents:
Key Provisions in Effect
- Two ADUs allowed per lot (can be 2 attached, 2 detached, or one of each)
- Minimum size cap: Jurisdictions cannot restrict ADUs to be smaller than 1,000 sq ft
- No owner-occupancy requirement: Owners aren’t required to live in either the main unit or the ADU(s)
- Impact fees capped at 50% of what’s charged for the primary residence
- Eased design and development constraints: Municipalities must not impose ADU-specific setback, height (< 24 ft), lot coverage, aesthetic, tree retention, entrance, or design standards stricter than for main homes; ADUs may even be built right up to alleys
- Parking flexibility: No parking required if within ½ mile of major transit; otherwise, 1 space for lots under 6,000 sq ft and 2 spaces for larger lots
- Convert existing structures like garages to ADUs even if they currently violate local setbacks or lot coverage
- Condominium conversions allowed: ADUs may be sold independently as condos
- CC&Rs may not impose new restrictions: Homeowners’ associations cannot, post-enactment, block lawful ADU construction on qualifying lots
Local Implementation in Pierce County
- Pierce County, including Tacoma, University Place, Lakewood, Puyallup, Gig Harbor, etc., was required to comply by December 31, 2024
- Most have adopted new regulations ahead of the June 30, 2025 deadline, while some smaller jurisdictions finalized changes in spring 2025.
- University Place, your community, falls within the deadline and has integrated these zoning updates into its municipal code well before July 2025.
What This Means for You in Pierce County
- Up to two ADUs per lot now allowed, including detached units — potentially valuable for rental income or multigenerational living.
- Flexible construction rules— can build up to 1,000 sq ft per unit without burdensome impact fees or parking requirements.
- No owner-occupancy rule, making it easier to use ADUs as rental units.
- Conversions of existing structures (like garages) are easier and often do not require variances.
- Condos allowed, unlocking new financing or sale options.
What to Do Next
If you’re considering building in Pierce County:
Fill out our form and Matt Rody, our owner, will give you a call and walk you through what your lot allows. Not every lot is equal, especially when it comes to septic. Septic tanks and drain fields create a lot more feasibility work and many times restrict a lot from having a DADU built.
Final Thoughts
HB 1337 is now fully in effect throughout Pierce County and its cities as of mid‑2025. For property owners in University Place and neighboring cities, it makes building one or two ADUs per lot significantly easier and more financially attractive. Whether you’re eyeing rental income, space for family, or expanding housing options in your community — now’s the time to explore it.
