Building permits, zoning and septic rules in Clackamas County, Oregon

At a glance

Building permit

Required for new homes, duplexes and most additions; some ag/equine/forestry buildings are exempt⁵

Zoning

Yes, county-administered in unincorporated areas under its own Zoning and Development Ordinance⁶

Septic authority

Clackamas County Septic Program⁷

Septic soils

Only 7.1% of soils rate free of severe limits for a conventional drain field⁸

Owner-builder

Allowed with a signed responsibility notice; the permit is still required⁹

RV as a second dwelling

One may be approved as a second dwelling on qualifying property¹⁰

Farm/forest minimum lot size

80 acres (160 acres for rangeland), set by the state¹¹

Tiny home on wheels

Cannot be used as an accessory dwelling unit¹²

Who to call

Contact details are copied from each office’s official page and were checked against it on October 14, 2026.

Do you need a building permit in Clackamas County, Oregon?

Clackamas County requires multiple permits for a new single-family home or duplex, and most additions or modifications to an existing home or duplex also require permits¹. The county building code incorporates Oregon's structural, residential, electrical, plumbing, mechanical and other specialty codes¹³. A qualifying agricultural building on farm- or forest-zoned property can avoid the building permit and building inspections, but land-use approval and electrical, plumbing, mechanical or erosion-control permits may still apply¹⁴. The exemption is limited to qualifying agricultural operations, excludes public use and does not cover a dwelling¹⁵. For permitted residential work, final trade inspections occur after the systems are complete and before occupancy, and the final building inspection follows approval of every other required inspection¹⁶¹⁷. County building and planning fee schedules are published, but the total varies with permit type, valuation, plan review, inspections and project details¹⁸.

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

Clackamas County Building Permitting is at the Development Services Building, 150 Beavercreek Road in Oregon City, and can be reached at 503-742-4240¹⁹. Zoning questions and land-use applications go to the Planning Division in the same building, Room #225, at 503-742-4500; planning applications must be filed through Development Direct or in person by appointment²⁰. The Septic Program, on the 2nd floor, handles onsite wastewater permits at 503-742-4740²¹. Floodplain development permits also go through the Planning Division²². Transportation Engineering handles county road right-of-way and engineering matters at 503-742-4691²³. Start with Planning for parcel use and siting, then coordinate with Septic when the property lacks community sewer, and submit the building package through Development Direct¹⁹.

Does Clackamas County have zoning?

Clackamas County administers state, regional and local zoning regulations in unincorporated areas²⁴. Incorporated cities have their own zoning authority, so property inside city limits must be checked with that city rather than the county; septic permits remain a separate county program³⁴. The county's zoning ordinance divides unincorporated land into districts shown on zoning maps, so look up the parcel's district first²⁵. The parcel's district matters: manufactured dwellings are primary uses in several urban districts, while other urban districts prohibit them²⁶. In the RA-1, RA-2, RR, RRFF-5, FF-10 and FU-10 rural and future-urban residential districts, a manufactured dwelling is a primary use, but each lot of record may generally hold only one principal dwelling, and zoning, building, floodplain and septic standards still apply²⁷. A rural accessory dwelling unit outside an urban growth boundary and unincorporated community requires a lot of at least 2 acres, is generally capped at 900 square feet, must sit within 100 feet of the primary dwelling and cannot be a short-term rental²⁸. A tiny home on wheels or similar mobile structure cannot serve as that ADU¹². Resource-land minimums are generally 80 acres for exclusive farm use or forestland and 160 acres for rangeland, subject to statutory exceptions¹¹.

How do septic permits work in Clackamas County?

The Clackamas County Septic Program regulates installation, repair and maintenance for homes and businesses not served by community sewer⁴. Replacing, repairing, altering or installing a septic system requires a construction permit; most permit types require an approved site evaluation, and a new system or alteration also requires a Land Use Compatibility Statement²⁹. A buildable lot needs direct access to sanitary sewer or an approved onsite sewage disposal system³⁰. A composting toilet does not eliminate the need for an approved wastewater system for the home's remaining wastewater³¹. An RV approved as a second dwelling must connect to sanitary sewer or a county-approved onsite wastewater system and have a working sink and toilet connected to that system³². Only 7.1% of county soils rate free of severe limits for a conventional drain field, making a site evaluation an important pre-purchase step⁸. An ADU, guest house, RV, bedroom addition or hardship dwelling using an existing system can trigger a professional inspection and Existing System Evaluation Report³³.

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

Unincorporated Clackamas County can approve one RV as a second dwelling on qualifying single-family residential property, but a Type I land-use application is required, the lot must already have exactly one eligible primary dwelling, and an owner must live there at least six months a year³⁴. The approval is valid for 4 years and must be kept active through maintained county development permits³⁴. The RV must sit 10 to 100 feet from the primary dwelling, have a written residential rental agreement, connect to approved sewage, potable water and electrical service, and stay outside the Floodplain Management District; neither dwelling may be used as a short-term rental¹⁰. This second-dwelling route is not general permission to camp on a vacant parcel. The county's separate recreational vehicle camping facility use in the RA-1, RA-2, RR, RRFF-5 and FF-10 districts is a conditional use reviewed under Section 813 and is prohibited in FU-10, so it is a campground-style business use rather than a way to live in an RV on your own lot³⁵. Oregon allows occupancy of a camping vehicle on private land only with the owner's consent, adequate space for approved water and sewage, and compliance with state and local sanitation and utility standards³⁶. County park rules separately prohibit overnight camping outside designated numbered spaces, but that rule applies to county park areas rather than private land³⁷. A tiny home on wheels cannot be used as an ADU, and we could not confirm one general occupancy classification for every other tiny-home design; ask Planning how the specific unit and parcel will be treated¹²²⁰.

How do you build a home in Clackamas County, step by step?

1. Confirm the zoning district, allowed dwelling type and any resource-land minimum by calling Planning at 503-742-4500²⁰¹¹.
2. If community sewer is unavailable, obtain the septic site evaluation and Land Use Compatibility Statement needed for the proposed system²⁹.
3. Identify the building, electrical, plumbing and mechanical permits the project requires, review the published fee schedules, then submit the drawings through Development Direct³⁸¹⁸.
4. Show the driveway and adjacent streets on the site plan, and obtain a floodplain development permit before work if the site is in the Floodplain Management District³⁹⁴⁰.
5. An owner who is not licensed with the Construction Contractors Board must sign the construction-responsibility statement before a residential permit can issue; hired subcontractors must hold the required licenses, and the permit cannot be transferred⁹⁴¹.
6. The separate owner-built structural exemption is narrow: it covers ceiling heights, room sizes and specified temperature requirements, does not remove the permit requirement, and may require the permit to be recorded with the county clerk⁴².
7. Complete every required trade inspection before the final building inspection and occupancy¹⁶. A certificate of occupancy is expressly required for new commercial, industrial and multi-family development, but the county source does not extend that requirement to an ordinary single-family home⁴³.

What should you check before buying land in Clackamas County?

From the county's center, the nearest city of 100,000 or more people is about 23 miles away, and Clackamas County has a population density of about 226 people per square mile⁴⁴⁴⁵. Federal land covers 53.4% of the county, so confirm that any parcel offered for sale is privately owned and legally buildable⁴⁶. About 83% of the land is wooded and just over half sits at a gentle 15% slope or less, so expect clearing and grading questions on a wooded, sloped parcel⁴⁷⁴⁸. Because only 7.1% of Clackamas County soils rate free of severe limits for a conventional drain field, budget for a site evaluation before closing on land without sewer⁸. For a private well, ordinary domestic groundwater use up to 15,000 gallons a day does not require a water-use permit, but well-construction standards still apply⁴⁹. A landowner drilling or altering a well personally generally needs a landowner permit, fee and financial bond before work unless licensed as a Water Supply Well Constructor⁵⁰.

Watch-outs

• A tiny home on wheels cannot serve as an accessory dwelling unit, and we could not confirm one general occupancy rule covering every other tiny-home design; ask Planning to classify the proposed unit before buying it¹²²⁰.
• We could not confirm a general minimum dwelling size for unincorporated Clackamas County; a qualifying owner-built dwelling has a narrow exemption for room-size and related structural provisions, but it still needs a permit⁴².
• The Oregon Structural Specialty Code used for commercial construction became fully mandatory in 2026, replacing the prior edition; confirm with Building Permitting which edition applies to your specific project date⁵¹.
• Short-term rentals in unincorporated Clackamas County must be registered, a new one needs a Land Use Compatibility Statement from the Planning Division first, and an RV does not qualify as the rental unit⁵²²⁰.

Sources

1. How to Apply for a Permit: Building, quoted and re-checked
2. Planning and Zoning, quoted and re-checked
3. Planning and Zoning, quoted and re-checked
4. Septic Program | Clackamas County, quoted and re-checked
5. How to Apply for a Permit: Building (2026 county census)
6. Planning and Zoning (2026 county census)
7. Septic Program | Clackamas County (2026 county census)
8. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
9. Information Notice to Owners About Construction Responsibilities (ORS 701.325(3)), quoted and re-checked
10. ADUs and RVs as options for secondary dwellings, quoted and re-checked
11. Oregon Revised Statutes, Chapter 215 (Oregon statewide rule), quoted and re-checked
12. FAQ: ADUs in Rural Residential Areas, quoted and re-checked
13. Title 9: Buildings, quoted and re-checked
14. Should My Building Be Ag Exempt?, quoted and re-checked
15. Oregon Revised Statutes, Chapter 455 (Oregon statewide rule), quoted and re-checked
16. Residential Inspections, quoted and re-checked
17. Residential Inspections, quoted and re-checked
18. Building Division Fees, quoted and re-checked
19. Clackamas County Building Permitting (clackamas.us)
20. Clackamas County Planning Division (clackamas.us)
21. Clackamas County Septic Program (clackamas.us)
22. Clackamas County Planning Division (Floodplain Management District) (clackamas.us)
23. Clackamas County Transportation Engineering (clackamas.us)
24. Planning and Zoning, quoted and re-checked
25. ZDO 103: Zoning Districts, quoted and re-checked
26. clackamas.us, quoted and re-checked
27. clackamas.us, quoted and re-checked
28. ZDO 839: Accessory Dwelling Units, quoted and re-checked
29. How to Apply for a Permit: Septic | Clackamas County, quoted and re-checked
30. Residential One- and Two-Family Dwellings and Accessory Structures | Clackamas County, quoted and re-checked
31. What do I do with the finished material? (Oregon statewide rule), quoted and re-checked
32. ZDO 847: Recreational Vehicles As Second Dwellings | Clackamas County, quoted and re-checked
33. Septic Program | Clackamas County, quoted and re-checked
34. ADUs and RVs as options for secondary dwellings, quoted and re-checked
35. ZDO 316, quoted and re-checked
36. Oregon Revised Statutes, ORS 446.125 Occupancy on private land (Oregon statewide rule), quoted and re-checked
37. clackamas.us, quoted and re-checked
38. How to Apply for a Permit: Building, quoted and re-checked
39. How to Apply for a Permit: Building, quoted and re-checked
40. ZDO 703: Floodplain Management District (FMD), quoted and re-checked
41. Oregon Revised Statutes, ORS 701.325, quoted and re-checked
42. oregon.gov, quoted and re-checked
43. Certificates of Occupancy Application Process, quoted and re-checked
44. Straight-line distance from the county center to the nearest city of 100,000+ people: Bolthole Index county data
45. Population density: Bolthole Index county data
46. Federal land share: Bolthole Index county data
47. Wooded share of land: Bolthole Index county data
48. Share of land at 15% slope or less: Bolthole Index county data
49. State water related permits user guide, quoted and re-checked
50. Landowner Constructed Wells | Oregon Water Resources Department, quoted and re-checked
51. Oregon Structural Specialty Code adoption (Oregon statewide rule), quoted and re-checked
52. clackamas.us, quoted and re-checked

Written October 14, 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.