Building permits, zoning and land rules in Blaine County, Idaho

At a glance

Building permit

Required before construction begins in unincorporated Blaine County¹

Zoning

County zoning districts and overlays apply in unincorporated areas²⁶

Septic

A public-health-district permit and inspection are required⁵⁷

RV living

Countywide rules for residential RV use could not be confirmed; ask Land Use⁸

Tiny home

County minutes describe a 150-square-foot home as acceptable; foundation, zoning and building review still control⁹¹⁰

Agricultural building

A district-specific building-permit exemption may apply, but a setback permit is still required¹¹

Owner-builder

Owners may do their own work without contractor registration if they meet Idaho's conditions; permits and inspections still apply¹²¹³

Private well

Obtain an IDWR drilling permit before drilling¹⁴

Who to call

Contact details are copied from each office’s official page and were checked against it on October 12, 2026.

Do you need a building permit in Blaine County, Idaho?

Yes. A building permit is required before construction begins in unincorporated Blaine County, and excavation counts as beginning construction.¹ Blaine County administers an adopted building code for covered construction; specific requirements depend on occupancy and construction type.¹⁵¹⁶ All county-regulated projects receive zoning review even when no building permit is required.¹⁷

One narrow exception applies to qualifying agricultural buildings in the A-20, A-40, R-10 and RR-40 zoning districts: those buildings do not require a building permit when they meet the county definition, but they still need a setback permit through Building Services.¹¹ Agricultural buildings outside those districts require building permits.¹¹ An exempt agricultural building cannot be used for human habitation, public use, or employment involving the processing, treatment or packaging of agricultural products.¹¹

Who is the Blaine County building department and how do you reach it?

Blaine County Building Services handles building permits and inspections for unincorporated land.¹ The office accepts digital plans only through the county's OpenGov portal.³ Building inspections can be requested at 208-788-5573, extension 1125, and covered projects require a final inspection.³¹⁸

Blaine County Land Use handles zoning review and accepts building and land-use applications electronically.¹⁹ Septic approval must be obtained before applying for a building permit.²⁰ For water, upload a private-well permit or, for municipal or community service, a will-serve letter.²¹ A complete application usually takes 4 weeks during the heavy building season from March through October; incomplete applications take longer.²²

Inside city limits, building permits are handled by Hailey²³, Ketchum²⁴, Bellevue²⁵, Sun Valley²⁶, Carey²⁷. South Central Public Health District remains the septic-permit authority for Blaine County addresses.⁴

Does Blaine County, Idaho have zoning?

Yes. Blaine County zoning and overlay districts apply in unincorporated Blaine County, with requirements varying by district.² Parcel requirements depend on the applicable zoning district, overlay district and approval procedure.¹⁰ Blaine County publishes zoning-district information.²⁸

Minimum lot size is district-specific rather than one countywide acreage,.²⁹ Blaine County lists an accessory-dwelling-unit conditional-use application; ask Land Use whether an ADU is allowed on the parcel.³⁰ Setbacks also vary by district and overlay.³¹ Ask Land Use to identify the district, overlays, minimum lot size and approval path before designing or dividing land.¹⁹

County zoning applies to unincorporated land; Hailey³², Bellevue³³, Sun Valley³⁴, Carey³⁵ set their own city zoning. Septic permitting stays with South Central Public Health District.⁴

How do septic permits work in Blaine County?

South Central Public Health District administers septic permitting in Blaine County, and a property owner must obtain a district permit before installing a new or repaired system.⁴⁵ The district performs site evaluations, sets system-specific requirements and inspects permitted installations.⁵⁷ The Bellevue office handles septic and land-development questions at (208) 788-4335 or septic@phd5.id.gov.³⁶

Off-grid does not mean sanitation is unregulated: Idaho standards govern the design, construction, siting and use of onsite wastewater systems, and alternative systems are limited to designs accepted under state rules.³⁷ We could not confirm whether composting toilets, graywater systems or every other non-septic method are allowed, so take a proposed setup to the health district before purchase.³⁷ Only about 1.9% of mapped county soils avoid a severe limitation rating for a conventional drain field, making site evaluation an early priority.³⁸

Can you live in an RV or tiny home in Blaine County?

We could not confirm a complete countywide rule for long-term RV occupancy or temporary camping on private land in unincorporated Blaine County. Ask Blaine County Land Use to review the parcel's zoning district, overlays and proposed duration before buying or moving a unit onto the land.¹⁹ Parcel requirements depend on the applicable district, overlays and approval procedure.¹⁰

County meeting minutes say a 150-square-foot home can be acceptable and that the county adopted a tiny-home code section for homes under 400 square feet, but they do not establish a universal minimum dwelling size.⁹ The same minutes say a home must be on a foundation to count as a single-family residence; otherwise it is treated as a trailer or RV.⁹ A separate A-40 rule allows temporary mobile or manufactured-home use during construction for no more than 1 year and permanent primary-residence use on at least 40 acres with builder certification to current county building standards.³⁹

Building a home in Blaine County: what are the steps?

1. Ask Blaine County Land Use to identify the parcel's zoning district and overlays and flag any land-use, ADU or floodplain approvals.²³⁰⁴⁰
2. Have South Central Public Health District evaluate the site and issue the required septic approval before the building application.⁵²⁰
3. Document water service with a private-well permit or a municipal or community-water will-serve letter.⁴¹²¹
4. Resolve access if there is no approved driveway: county-road access requires a Blaine County permit, state-highway access requires an ITD permit, and private-road access does not require the listed county permit; wait for approval confirmation before access work.⁴²
5. Submit the building application and digital plans through OpenGov before construction or excavation begins.²⁰¹
6. Schedule the required inspections, including the final inspection, and obtain the certificate of occupancy for covered work.¹⁸⁴³

What should you check before buying land in Blaine County?

Start with the zoning district, overlays, minimum lot size and legal access, then put septic and water feasibility ahead of house plans.²²⁹⁴²⁵ Dividing land triggers county subdivision review, with standards and procedures depending on the application type.⁴⁴ About 42.8% of county land has a slope of 15% or less.⁴⁵

All development in Blaine County floodplains, including grading, fill and bank stabilization, requires county review; the first floor of living space, mechanical systems and services must be at least 2 feet above mapped flood level.⁴⁶ For budgeting context, the county's effective property-tax rate is about 0.4%, with a median annual property-tax bill of $2,563.⁴⁷⁴⁸

Watch-outs

• Do not excavate before the building permit is issued; Blaine County treats excavation as the start of construction.¹
• Use Blaine County’s fee schedule rather than amounts printed on application forms, which may be incorrect; building plan check adds 65% of the building permit fee, and fire-department plan check adds 40% of the plan-check fee.⁴⁹⁵⁰
• Do not rely on a countywide acreage for minimum lot size; the standard depends on the zoning district, and dividing land triggers subdivision review.²⁹⁴⁴
• An Idaho owner who works on the owner's own land and does not intend to sell within 12 months may be exempt from contractor registration, but Blaine County building permits, zoning review and inspections still apply when required.⁵¹

Sources

1. Frequently Asked Questions - Building Services, quoted and re-checked
2. Blaine County Ordinance No. 2025-08, quoted and re-checked
3. Blaine County Building Services (blainecountyid.gov)
4. phd5.idaho.gov, quoted and re-checked
5. deq.idaho.gov, quoted and re-checked
6. Blaine County Ordinance No. 2025-08, quoted and re-checked
7. Septic and Septage, quoted and re-checked
8. Blaine County Ordinance No. 2025-08 (2026 county census)
9. Blaine County Planning & Zoning Commission Minutes — January 23, 2020, quoted and re-checked
10. Blaine County Ordinance No. 2025-08, quoted and re-checked
11. Blaine County Frequently Asked Questions, quoted and re-checked
12. Frequently Asked Questions (FAQ) - Division of Occupational and Professional Licenses (Idaho statewide rule), quoted and re-checked
13. How To Purchase a Trade Permit (Idaho statewide rule), quoted and re-checked
14. Idaho Department of Environmental Quality: Wells, quoted and re-checked
15. Building Services, quoted and re-checked
16. blainecountyid.gov, quoted and re-checked
17. Blaine County Frequently Asked Questions, quoted and re-checked
18. blainecountyid.gov, quoted and re-checked
19. Blaine County Land Use (blainecountyid.gov)
20. Blaine County Building Services BP Checklist 2026, quoted and re-checked
21. Blaine County Building Services Checklist for a Complete Building Permit Application, quoted and re-checked
22. blainecountyid.gov, quoted and re-checked
23. Hailey: Building Services (Blaine County), quoted and re-checked
24. Ketchum: Ketchum Code of Ordinances, § 15.12.020—Definitions (Blaine County), quoted and re-checked
25. Bellevue: 9-1-3: Exemptions (Blaine County), quoted and re-checked
26. Sun Valley: 8-4-2: Definitions (Blaine County), quoted and re-checked
27. Carey: Do I need a building permit? How do I apply for a permit? (Blaine County), quoted and re-checked
28. Blaine County GIS Map Services, quoted and re-checked
29. Blaine County Ordinance No. 2025-08, quoted and re-checked
30. Blaine County Land Use & Building Services Department 2025 Fee Schedule, quoted and re-checked
31. Blaine County Ordinance No. 2025-08, quoted and re-checked
32. Hailey: Hailey, ID Code of Ordinances (Blaine County), quoted and re-checked
33. Bellevue: Title 10, Chapter 1: Title; Purpose; Interpretation (Blaine County), quoted and re-checked
34. Sun Valley: 9-2-1: Zoning Districts Established (Blaine County), quoted and re-checked
35. Carey: Planning and Zoning Regular Meeting 03/06/2023 (Blaine County), quoted and re-checked
36. South Central Public Health District (phd5.idaho.gov)
37. Septic and Septage, quoted and re-checked
38. 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
39. Blaine County Ordinance No. 2025-08, quoted and re-checked
40. Blaine County Building Services Checklist for a Complete Building Permit Application, quoted and re-checked
41. Blaine County Building Services BP Checklist 2026, quoted and re-checked
42. Blaine County Building Services BP Checklist 2026, quoted and re-checked
43. blainecountyid.gov, quoted and re-checked
44. Land Use Application Forms — Subdivision, quoted and re-checked
45. Share of land at 15% slope or less: Bolthole Index county data
46. Floodplain Management & Regulations, quoted and re-checked
47. Effective property tax rate: Bolthole Index county data
48. Median property tax bill: Bolthole Index county data
49. Land Use Application Forms, quoted and re-checked
50. Local Jurisdictional Fees, quoted and re-checked
51. Frequently Asked Questions — Idaho Contractors Board, quoted and re-checked

Written October 12, 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.