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

At a glance

Building permit

Required in unincorporated Skagit County, issued by Planning & Development Services (PDS)¹

Zoning

Yes, countywide, administered by PDS under the Growth Management Act; forest districts set 20- and 80-acre minimum lot sizes²⁵

Septic permit

Skagit County Public Health's On-Site Sewage Program, not the state directly; permits run up to 5 years³⁶

Owner-builder

You can work on your own property without contractor registration, but building permits still apply⁴⁷

Permit fees

Plan review runs 65% of the building permit fee; inspections are $155/hour (1-hour minimum)⁸

Minimum dwelling size

State building code requires at least 190 sq ft of habitable space⁹

Tiny home on wheels

Allowed up to 400 sq ft if built to the state building code; approval depends on where you place it¹⁰

Septic soils

Only about 0.2% of the county's soils carry no severe rating for a conventional drain field¹¹

Who to call

Contact details are copied from each office’s official page and were checked against it on September 25, 2026.

Do you need a building permit in Skagit County, Washington?

Yes: unincorporated Skagit County requires a building permit for a home, issued by Planning & Development Services (PDS), which enforces the Washington State Building Code countywide¹. Washington's state code is adopted by reference in every county and city in the state, so Skagit County cannot opt out of it, and the county's own inspection process follows from that adoption¹². Counties may adopt a narrow local exemption for small Group R-3 (residential) or Group M-1 projects worth no more than $1,500 in fair-market value in a 12-month period, but that exemption does not remove electrical, plumbing or mechanical permit requirements, and it does not apply to a new home¹³. Once a permit is issued, the inspection card that comes with it can include setback, foundation, framing, plumbing, mechanical, electrical, insulation, energy-code, drywall and final-occupancy inspections depending on the project¹⁴. One carve-out that matters for rural buyers: a temporary growing structure used solely to produce horticultural plants (a greenhouse or hoop house, for example) is not treated as a building or structure under the state building-code chapter at all¹⁵.

Who is the Skagit County building department, and how do you reach them?

Skagit County Planning & Development Services (PDS) is the building department for unincorporated Skagit County: it issues building, floodplain and grading permits and administers zoning¹². PDS is physically and by mail at 1800 Continental Place, Mount Vernon, WA 98273¹⁶. Its reception counter is open Monday through Friday, 8:00am to 4:30pm, and the general phone line is 360-416-1320; a separate inspection line, 360-416-1330, handles scheduling once a permit is issued¹⁶. General questions go to [email protected]¹⁶. Applications go through the county's Civic Access portal, where you create an account, select Apply, and follow the application through submittal and payment¹⁷. Before you submit, have septic, water, access (driveway) and address approvals in hand: PDS's own FAQ lists these as prerequisites for permit submittal¹⁸. Plan review runs 65% of the building permit fee and inspections bill at $155 per hour with a one-hour minimum; a temporary certificate of occupancy, where one applies, costs $315⁸¹⁹.

Does Skagit County have zoning?

Yes: Skagit County zones all unincorporated land under Skagit County Code Chapter 14.16, adopted under the state Growth Management Act, and PDS administers it². Washington law lets a county's zoning regulate land uses, minimum lot size, setbacks, yards, lot coverage, building height and minimum gross floor area for single-family homes, so those numbers vary by the zoning district your parcel sits in rather than by one countywide figure²⁰. The county's own forest-zoning rules show how much this varies: Secondary Forest land carries a 20-acre minimum lot size and Industrial Forest carries an 80-acre minimum, and a house in Industrial Forest must be accessory to timber management, sit within 200 feet of a county road or state highway, and be inside a fire district⁵²¹. Agricultural land gets one narrow carve-out: the county's Agricultural Land Preservation Code lets an existing house on a qualifying Ag-NRL or RR-NRL lot of record be subdivided onto a one-acre tract if the owner donates a conservation easement over the remainder²². Accessory dwelling units are a separate story: state law requires Skagit County to allow at least two ADUs on qualifying lots, but only on lots inside a designated urban growth area; outside an urban growth area, this statewide mandate does not apply²³. Any home built under the state building code, anywhere in the county, must have at least 190 square feet of habitable space, with at least one room of at least 120 square feet and other habitable rooms of at least 70 square feet (kitchens are exempt from the minimum)⁹.

How do septic permits work in Skagit County?

Skagit County Public Health, not the Washington State Department of Health directly, administers the On-Site Sewage Program and reviews site evaluations and permit applications for individual systems and community systems flowing under 3,500 gallons per day²⁴. A permit is required before installing a new system, replacing one, or doing a non-minor repair or a remodel that increases capacity; your system designer submits the application, site and soil evaluation, site plan and design through the county's Civic Access portal²⁵. Repair permits are valid for one year and other septic permits for three years, which is narrower than the five-year maximum state law allows local health officers to set²⁵⁶. Before backfill, Skagit County Public Health conducts a final installation inspection, and your installer must request it at least two full working days in advance; after that, conventional gravity systems need a follow-up inspection every three years, while other system types are inspected annually²⁶. Soils are a real factor here: USDA soil-survey data rates only about 0.2% of Skagit County's soils as free of severe limitations for a conventional septic drain field, so most parcels should expect a site evaluation and, in many cases, an engineered or alternative system rather than a standard gravity drain field¹¹. Reach Skagit County Public Health at (360) 416-1500 or 301 Valley Mall Way, Suite 110, Mount Vernon, WA 98273²⁷.

Can you live in an RV or tiny home on your land in Skagit County?

Washington state law defines a recreational vehicle as temporary, transient living quarters that is "not occupied as a primary residence" in the context of manufactured/mobile-home community rules, but that definition does not by itself say whether Skagit County allows an RV as a residence on private rural land while you build²⁸. We could not confirm Skagit County's own zoning rule for RV occupancy on a private parcel in the sources reviewed for this guide; call PDS before you plan to live in an RV on your land¹⁶. A movable tiny house is treated differently: Washington allows a tiny house built on wheels, up to 400 square feet including kitchen, bathroom and sleeping area, if it is built to the Washington State Building Code, but the approval process depends on where it will sit, so check with PDS about foundation, installation and location requirements before you buy or place one¹⁰.

Building a home in Skagit County: the steps, in order

1. Confirm your parcel's zoning district, minimum lot size and any overlay (floodplain, critical area, forest or agricultural district) with Planning & Development Services before you design anything; call 360-416-1320 or email [email protected]¹⁶⁵.
2. If your land is in a floodplain, plan for a floodplain development permit alongside your building permit; PDS administers it for unincorporated Skagit County under the National Flood Insurance Program²⁹.
3. Apply for a septic (on-site sewage) permit through Skagit County Public Health's Civic Access portal before construction begins, with your designer's site and soil evaluation and system design attached; the permit runs one to three years depending on type²⁵²⁷.
4. Have your access (driveway), water and address approvals completed, then submit your complete building permit application to PDS through Civic Access; plan review runs 65% of the building-permit fee¹⁸⁸¹⁷.
5. If you're acting as your own contractor, you don't need to register under Washington's contractor law, but you still need the building permit and any separately regulated electrical or plumbing permits⁴⁷.
6. If you plan to build a driveway approach, get permission first: from the county board for a county road, or in writing from WSDOT for a state highway³⁰³¹.
7. Expect an inspection card with your permit; Public Health conducts a final septic inspection before backfill with two full working days' notice, and PDS's own inspections vary by project²⁶¹⁴.

What to check before you buy land in Skagit County

Soils and septic: only about 0.2% of Skagit County's soils rate free of severe limitations for a conventional septic drain field, so budget for a site evaluation and possibly an engineered system almost anywhere in the county¹¹. Zoning district: minimum lot sizes swing sharply by district, from 20 acres in Secondary Forest to 80 acres in Industrial Forest, so confirm your parcel's zone with PDS before you assume what you can build or subdivide⁵. Terrain: about 19.8% of the county sits at 15% slope or less and 75.4% is wooded, so expect steep, forested ground outside the valley floor, which affects driveway grading, septic siting and construction cost³²³³. About half the county, 50.6%, is federal land, which limits where private parcels exist and what borders them³⁴. Distance and climate: Skagit County sits roughly 36 straight-line miles from the nearest city of 100,000 or more people, gets about 80 inches of precipitation a year, and has been in severe drought about 5.7% of years³⁵³⁶³⁷. Money: the effective property tax rate runs about 0.8%, with a median annual bill near $4,008, and a typical home insurance premium of about $1,178 a year³⁸³⁹⁴⁰.

Watch-outs

• We could not confirm Skagit County's own rule on living in an RV on private land while building; the only sourced RV definition is a statewide manufactured/mobile-home-community rule, not a land-use answer, so call PDS before you count on it¹⁶.
• Accessory dwelling units are a state-mandated right only on qualifying lots inside a designated urban growth area; most rural, unincorporated Skagit County land sits outside those areas, where ADU rules are set locally instead²³.
• Septic permit validity in Skagit County (one year for repairs, three years otherwise) is shorter than the five-year maximum Washington law allows local health officers to set, so don't assume the state's five-year figure applies here²⁵⁶.

Sources

1. Skagit County - Planning & Development Building Permit Page (2026 county census)
2. Skagit County Code Ch. 14.16 - Zoning (2026 county census)
3. Sewage (2026 county census)
4. Washington State Legislature - RCW 18.27.090 Exemptions (2026 county census)
5. Agricultural and Forest Lands, quoted and re-checked
6. WAC 246-272A-0200 Permit requirements (Washington statewide rule), quoted and re-checked
7. RCW 18.27.090 Exemptions, quoted and re-checked
8. Skagit County Permit Fee Schedules, quoted and re-checked
9. WAC 51-50-1208 — Section 1208—Interior space dimensions (Washington statewide rule), quoted and re-checked
10. Tiny Houses (Washington statewide rule), quoted and re-checked
11. Share of soils without severe limits for a conventional septic drain field (USDA SSURGO): Bolthole Index county data
12. Chapter 19.27 RCW: State Building Code, quoted and re-checked
13. WAC 51-16-080 — Permit exemptions guideline (Washington statewide rule), quoted and re-checked
14. Skagit County Planning and Development Services FAQ, quoted and re-checked
15. RCW 19.27.065 — Exemption—Temporary growing structures used for production of horticultural plants (Washington statewide rule), quoted and re-checked
16. Skagit County Planning & Development Services (skagitcounty.net)
17. Planning & Development Building Permit Page, quoted and re-checked
18. Skagit County Planning and Development Services FAQ, quoted and re-checked
19. Skagit County Planning and Development Services FAQ, quoted and re-checked
20. RCW 36.70.050 — Authority for planning (Washington statewide rule), quoted and re-checked
21. Agricultural and Forest Lands, quoted and re-checked
22. Agricultural and Forest Lands, quoted and re-checked
23. RCW 36.70A.680 — Accessory dwelling units—Local regulation (Washington statewide rule), quoted and re-checked
24. Sewage, quoted and re-checked
25. On Site Sewage Program Information, quoted and re-checked
26. On Site Sewage Program Information, quoted and re-checked
27. Skagit County Public Health (skagitcounty.net)
28. RCW 59.30.020 — Definitions (Washington statewide rule), quoted and re-checked
29. Planning & regulation — Washington State Department of Ecology (Washington statewide rule), quoted and re-checked
30. RCW 36.75.130 — Approaches to county roads—Rules regarding construction—Penalty (Washington statewide rule), quoted and re-checked
31. RCW 47.32.150 — Approach roads, other appurtenances—Permit (Washington statewide rule), quoted and re-checked
32. Share of land at 15% slope or less: Bolthole Index county data
33. Wooded share of land: Bolthole Index county data
34. Federal land share: Bolthole Index county data
35. Distance to the nearest metro area: Bolthole Index county data
36. Annual precipitation: Bolthole Index county data
37. Share of years in severe drought: Bolthole Index county data
38. Effective property tax rate: Bolthole Index county data
39. Median property tax bill: Bolthole Index county data
40. Typical home insurance premium: Bolthole Index county data

Written September 25, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.