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

Yes. Cassia County requires a permit to construct, erect, relocate or remodel a building covered by its adopted building code^1,4. A one-story detached accessory structure over 200 square feet also requires a permit, subject to the county's stated residential-code exceptions¹. Agricultural buildings defined by the building code can be exempt from the adopted building codes, but zoning placement requirements and permits still apply⁴. Manufactured and mobile homes need a placement permit before installation, and older units must meet the stated federal requirements¹. Electrical, plumbing and HVAC work requires separate state permits⁹. County inspections include setbacks, footings, foundation, rough framing, energy, wall board and final stages, and requests require at least six business hours' notice¹. Final county approval is required before a permitted structure is used or occupied⁹.

Cassia County Zoning and Building Department is the starting point for building permits, inspections and land-use questions⁵. The office is in the Cassia County Courthouse at 1459 Overland Ave., Room 210, Burley, Idaho 83318; call 208-878-7302 or email bldgdept@cassia.gov⁵. Cassia County publishes applications for building permits, accessory dwellings, manufactured-home placement, floodplain development, subdivisions, temporary placement and other land-use reviews¹⁰. A building application requires two plan sets covering the site, foundation or basement, floor plan, elevations, exterior and roof details, wall section, and window and door schedule or energy documentation⁹. Building-permit fees are calculated from square footage and the county's valuation table, and the county lists a $200 residential plan review fee and a $25 floodplain development permit fee; ask the department to confirm the current total before submitting¹¹. Development in a Special Flood Hazard Area requires a floodplain development application before work begins¹².

Yes. Cassia County publishes zoning regulations and an official zoning map³. For dwellings in unincorporated Cassia County, the general minimum lot area is 1 acre, with county-code exceptions; the health authority can determine the minimum where groundwater or soil conditions warrant, and approved subdivisions with central sewer or water may qualify for smaller lots¹. Outside subdivision lots, principal-building setbacks are generally 54 feet from the center of an adjoining street and 15 feet at the rear and interior side; the Industrial Commercial zone uses 5 feet at the rear and interior side¹. Accessory-building placement is different, so confirm the parcel's district and proposed structure with Zoning and Building¹. Building-height limits also vary by zoning district¹³. County zoning regulations apply in unincorporated Cassia County, and incorporated municipalities may have separate rules, so ask the relevant city for zoning approval and building permits if the parcel is inside city limits¹; we could not confirm who handles septic permits inside city limits beyond the district's service area, so call South Central Public Health District. Anyone dividing unincorporated land should consult Planning and Zoning before preparing plats or plans¹⁴.

South Central Public Health District serves Cassia County and reviews applications for new and repaired septic systems^2,15. The district's Heyburn office is at 485 22nd Street, Heyburn, ID 83336; call (208) 678-8221 or email septic@phd5.id.gov². Idaho's public health districts administer the statewide individual and subsurface sewage-disposal rules under an agreement with the Department of Environmental Quality¹⁶. A septic system cannot receive wastewater until the required final installation inspection occurs, and inspection preparation can require at least 48 hours' notice excluding weekends and holidays¹⁷. Only 26.7% of Cassia County soils are rated without severe limitations for a conventional septic drain field, so evaluate the actual homesite early¹⁸. If public or central wastewater treatment is reasonably accessible, the permitting authority may deny an onsite-system permit¹⁹.

We could not confirm a general Cassia County rule allowing or prohibiting residential or long-term RV occupancy on private land. Ask the Zoning and Building Department about the parcel's district, the proposed length and purpose of occupancy, and whether a temporary-placement permit applies⁵. We also could not confirm the operative county rules for tiny-home occupancy or a general minimum dwelling floor area. A small dwelling still has to fit the county zoning, building-permit and septic requirements^1,3,15. A manufactured or mobile home has a defined route: Cassia County requires a placement permit before installation, and zoning controls also apply¹. Manufactured-home installations must be inspected and approved before occupancy²⁰. Cassia County publishes an accessory-dwelling application, but the specific allowance and limits should be confirmed with Zoning and Building¹⁰.

1. Ask Cassia County Zoning and Building to confirm the zoning district, minimum lot area, setbacks, allowed use and floodplain status before choosing a house location^1,3,12.

1. Contact South Central Public Health District early for septic review, because the district issues the septic permit and much of the county's soil is rated severely limited for a conventional drain field^2,18.

1. If the project needs a private well, obtain the Idaho Department of Water Resources drilling permit and use a licensed well driller⁸.

1. If access connects to a state highway, obtain an Idaho Transportation Department encroachment permit before work in the highway right-of-way²¹.

1. Submit two sets of the required building plans, confirm the current fees, and obtain separate state permits for electrical, plumbing and HVAC work^9,11.

1. Schedule the county building inspections at least six business hours ahead, and complete final building and septic approvals before occupancy or wastewater discharge^1,9,17.

Start with legal buildability: have Cassia County Zoning and Building confirm the zoning district, allowed dwelling type, setbacks, lot-size exceptions and whether the proposed homesite lies in a Special Flood Hazard Area^1,3,12. Check wastewater feasibility before closing, because only 26.7% of county soils are rated without severe limits for a conventional septic drain field¹⁸. For an undeveloped parcel, verify a legal and practical water source; Idaho requires a drilling permit before a well is drilled⁸. Annual precipitation averages 16.2 inches, and severe drought occurs in 15.8% of years, making water planning a central purchase question¹⁸. Federal land makes up 52.8% of Cassia County, so verify boundaries and recorded access rather than assuming adjoining public land provides access¹⁸. A driveway connecting to an Idaho state highway needs an encroachment permit²¹. The effective property-tax rate is about 0.4%, with a median annual bill of $1,141¹⁸.