Published August 5, 2025

Why HB 1337 Matters to You

Written by Stacy LaCount

Why HB 1337 Matters to You header image.

🏡 HB 1337: What Washington’s New ADU Law Means for Skagit County Homeowners

Thinking about building a backyard cottage, basement suite, or detached rental?

Thanks to House Bill 1337, it’s now much easier to add an Accessory Dwelling Unit (ADU) to your property in Skagit County—especially if you’re in Mount Vernon, Anacortes, Sedro-Woolley, or Burlington.

This 2023 legislation was designed to tackle Washington’s housing shortage and gives homeowners more freedom, flexibility, and financial opportunity to expand their living space.

🔍 What Is HB 1337?

House Bill 1337 is a statewide law that overrides many local zoning restrictions, requiring cities and counties to allow at least two ADUs per residential lot and to streamline the permitting process. It goes into full effect across most jurisdictions by mid-2025, though many cities are already adopting the changes.

✅ Key Benefits for Homeowners in Skagit County

If you own property in an Urban Growth Area (UGA) in Skagit County, here’s what you need to know:

✔ Two ADUs per lot

You can now build two ADUs- either attached, detached, or converted from existing structures like a garage or basement.

✔ Up to 1,000 square feet

Local codes must now allow ADUs to be at least 1,000 sq. ft., giving you room for full living quarters.

✔ No owner-occupancy requirement

You no longer have to live on-site to build or rent out your ADU. This opens doors for rental income or multi-generational living.

✔ Lower impact fees

Cities and counties can’t charge more than 50% of regular impact fees for an ADU, meaning you save on upfront costs.

✔ Simplified design & permitting

Height limits, setbacks, and aesthetic standards must be fair and consistent with main homes. Cities must also provide a faster, less subjective approval process.

✔ Sell or condo-ize your ADU

HB 1337 allows you to condo and sell your ADU separately, subject to building codes and legal review.

🗺 Where Does HB 1337 Apply in Skagit County?

This law applies to any property within a city or urban growth boundary, such as:

Mount Vernon
Anacortes
Sedro-Woolley
Burlington
Concrete (if within a UGA boundary)

If you’re outside of a UGA (more rural areas), local ADU rules still apply, but they may not be as flexible. However, HB 1337 sets a clear direction toward more permissive rules statewide.