ADU (accessory dwelling unit) Planning in Skagit County, WA (2026)

The first step for a Skagit County ADU is to identify who reviews the property. A Mount Vernon, Burlington, Anacortes, or Sedro-Woolley mailing address can refer to land outside that city’s limits. Incorporated cities, unincorporated urban growth areas, and rural county land can have different dwelling rules.

Use adopted zoning for your parcel

Skagit County’s official building and land-use page directs applicants to the current county code. Title 14 covers land use and development; Title 15 covers building requirements. Start with the parcel’s zone and the allowed-use provisions, then check the standards for the proposed dwelling.

If a code reorganization is in draft, the adopted code still governs your application. Don’t pick between an older size limit and a proposed larger one based on the model you like. Ask Planning to confirm the adopted section applicable to your application, including any recent amendments.

What to confirm before selecting a home

Have the responsible planning office identify:

• Whether an ADU is allowed in the zone and whether it may be detached.
• The permitted number of units, maximum floor area, height, setbacks, and lot coverage.
• Any restrictions associated with agricultural or other designated resource land.
• Required parking and emergency access.
• Any applicable occupancy, rental, or recorded-title conditions.

Washington’s urban ADU provisions do not automatically establish the same rights on rural land. Our Washington ADU guide explains that distinction; the property’s actual jurisdiction still controls the application path.

Check water, septic, and site constraints

Obtain the water-service or well records and the approved septic design. Confirm both an adequate legal water supply and capacity for the proposed dwelling. Where sewer is available, obtain the connection requirements from the provider. An existing connection does not establish the cost or capacity of adding another home.

Check floodplain, shoreline, wetlands, streams, and other critical-area requirements before deciding where the home will sit. Elevation requirements, drainage, a septic reserve area, or a restricted access route can reduce the usable footprint even where zoning allows an ADU.

Modular construction and site approval

A modular ADU still needs the applicable local placement, foundation, utilities, and inspection approvals. Wolf checks the route to the property, driveway width and turns, staging space, and trailer or crane setting needs alongside the proposed home location.

Review the home and project cost guide for starting prices and site-work considerations. Cost guidance does not establish zoning eligibility or replace a parcel review.

Start with the address

Send the property address or parcel number, your intended use, and the approximate size you need. Keep existing permit records, surveys, and water/septic information available. We will start with jurisdiction and site feasibility before narrowing the model choices.

Request a free Wolf property evaluation.

General planning information. Confirm current adopted requirements and fees with the county or city before committing to a design.