Building permits, zoning and septic rules in Skagit County, Washington

Yes. Unincorporated Skagit County generally requires the applicable building, mechanical, hot-water-tank replacement, demolition or grading permit for construction and related work¹. The county has adopted Washington's building, residential, mechanical, plumbing, fire and energy codes, with local amendments². A one-story detached building of no more than 200 square feet can be exempt only when it is not used for sleeping and meets the county's setback, flood, critical-area, plumbing and water-source conditions¹. Permit exemptions do not make an otherwise regulated use or location legal¹. After issuance, the inspection card identifies the project-specific inspections, which may cover setbacks, foundation, framing, trades, insulation, energy code, drywall and final occupancy¹¹.

Skagit County Planning & Development Services is the building and zoning contact for unincorporated Skagit County². The office is at 1800 Continental Place, Mount Vernon, WA 98273; call 360-416-1320, email pds@co.skagit.wa.us, or use the separate inspection line at 360-416-1330¹². County applications go through Civic Access, where applicants select the permit, provide the requested material, respond to corrections, complete related records and pay the invoice¹³. Complete septic, water, driveway-access and address approvals before submitting the building application¹¹. Published fees vary by permit, valuation, review and inspection; building plan review is 65% of the permit fee, inspections are $155 per hour with a one-hour minimum, and a temporary certificate of occupancy costs $315 where applicable¹⁴.

Yes. Skagit County's Title 14 zoning applies in unincorporated areas; incorporated municipalities and tribal lands may have different authorities². Allowed uses and dimensional standards depend on the parcel's mapped zoning district, so verify the district before relying on a countywide answer about setbacks, lot coverage or use⁵. Secondary Forest zoning has a 20-acre minimum lot size, while Industrial Forest zoning has an 80-acre minimum¹⁵. In Industrial Forest, a residence must support timber management, lie within 200 feet of a county road or state highway, and be within a fire district¹⁵. A qualifying Ag-NRL or RR-NRL lot of record may be divided to create a one-acre tract for an existing house only when the owner grants a conservation easement over the remainder¹⁵. The county materials do not establish one current zoning minimum dwelling size for every district; Planning & Development Services should confirm the standard for the parcel¹².

Skagit County Public Health reviews site evaluations and permits individual systems and community on-site systems below 3,500 gallons per day³. New and repair systems require county permit review and issuance³. An application includes the soil and site evaluation, site plan, proposed design and fees; repair permits expire after one year and other septic permits after three years¹⁶. Skagit County Public Health inspects the installation before backfill after the installer gives two full working days' notice, and routine inspection intervals range from one to three years by system type¹⁶. A structure not connected to sewer still needs an approved, permitted on-site sewage system for the county's listed new-construction, replacement, repair and capacity-increasing remodel situations; the county material does not establish approval for other off-grid sanitation methods¹⁷. Only about 0.2% of county soils avoid a severe conventional-drain-field rating, making a parcel-specific evaluation especially important¹⁰. Call Public Health at (360) 416-1500¹⁸.

An RV cannot be used as a permanent or primary residence in Skagit County⁶. Temporary RV occupancy is limited to 180 days in any 12-month period, with no more than one occupied RV on a lot⁶. Floodway parcels have extra limits: an RV must remain licensed, highway-ready, wheeled and free of permanent additions, and it generally cannot remain there from November through April except for weekend or holiday use lasting no more than 14 days⁶. A tiny house on wheels may contain up to 400 square feet and must meet the Washington State Building Code, but foundation, installation and location approval depend on where it is placed⁸. A tiny home built on a trailer or park-model chassis that meets the county's recreational-vehicle definition does not qualify as a dwelling unit or as an accessory dwelling unit in unincorporated Skagit County⁹. Ask Planning & Development Services how the county would classify a specific tiny home before buying or placing one¹².

1. Identify the parcel's zoning district and allowed use with Planning & Development Services before designing the home^5,12.
2. Check flood and critical-area constraints; development in a Special Flood Hazard Area requires a flood permit, and a designated floodway defeats the small-building exemption^1,19.
3. Arrange water and sanitation; a licensed driller obtains an individual-well permit from the Washington State Department of Ecology, while Skagit County Public Health handles the septic permit^3,20.
4. Complete septic, water, driveway-access and address approvals before submitting the building application¹¹.
5. Apply and pay through Civic Access, then answer correction requests and complete related records¹³.
6. An owner-builder exemption may remove contractor-registration requirements, but it does not remove building, electrical, plumbing or septic permits⁴.
7. Follow the building inspection card and arrange the Public Health inspection before the septic system is backfilled^11,17.

Confirm the zoning district and overlays before assuming a house, RV, subdivision or accessory use is allowed^5,6. Secondary Forest and Industrial Forest alone illustrate the variation, with 20-acre and 80-acre minimum lots respectively¹⁵. For a subdivision, county rules govern roads, sewer or community-septic improvements, and driveway easements; those easements must be at least 20 feet wide and may need added width for cuts, fills or slopes²¹. Check FEMA-related constraints early because development in a Special Flood Hazard Area requires a county flood permit¹⁹. Test water and septic feasibility before closing: individual wells use a state permit obtained by a licensed driller, and only about 0.2% of county soils avoid a severe conventional-drain-field rating^10,20. Skagit County's effective property-tax rate is about 0.8%, and its median annual property-tax bill is about $4,008¹⁰.