Thinking about adding an Accessory Dwelling Unit (ADU) — often called a granny flat, mother-in-law suite, or backyard cottage — in Vancouver or Clark County? 2026 is one of the best times in years to explore the option.Washington’s House Bill 1337 and local updates now make it significantly easier. Most residential lots in urban growth areas can have up to two ADUs in addition to the primary home. Owner-occupancy requirements have been removed, impact fees are reduced, and size limits are clearer.Key 2026 Rules at a Glance (City of Vancouver & Clark County Urban Areas)
- Up to two ADUs per lot (attached, detached, or one of each)
- Maximum size typically 1,000 square feet (some flexibility on larger lots)
- No requirement that the owner live on the property
- Impact fees capped lower than a primary home
- Starting July 31, 2026, additional flexibility for the number of residential structures on a single lot
Always confirm exact zoning and permits with the City of Vancouver or Clark County Community Development — rules can vary slightly by zone.Why Homeowners Are Building ADUs Right Now
- Generate rental income (studio or 1-bedroom ADUs often rent for solid monthly cash flow)
- House aging parents or adult children without everyone sharing the main house
- Increase property value and future resale appeal
- Create a flexible home office, guest suite, or Airbnb option
Rough Cost Ranges in 2026
Conversion of existing space (basement/garage): often $80,000–$150,000
New detached ADU: typically $180,000–$350,000+ depending on finishes and size The permitting process is more streamlined than it used to be, but working with a local contractor who knows Clark County codes makes a big difference.If you’re buying a home and want one with ADU potential (or already own one and are curious), I can help you evaluate feasibility, zoning, and how an ADU fits your long-term goals.Ready to explore whether an ADU makes sense for your property? Reach out — I’d love to walk you through the local options.
