Canyon County, ID Building Setbacks & Zoning: Lot Coverage Limits (2026)

Canyon County Code § 07-10-15, 'Property Boundary Coverage,' draws a hard line between zone types. In the Agricultural Zone A and the Residential Zones R-R, R-1 and R-2, the county states plainly that there are no county regulations on the maximum area of a lot that impervious surface may occupy, so a rural homeowner or farmer can pave, roof or otherwise cover a parcel without a countywide percentage ceiling. In the Commercial and Industrial Zones (C-1, C-2, M-1, M-2 and MU-A), the same section caps impervious surface, which includes buildings, parking lots, driveways and other non-permeable ground cover, at eighty five percent (85%) of the total lot area.

The provision was adopted by Ordinance 10-006 on August 16, 2010, as part of the Canyon County Zoning Ordinance in Chapter 7. Canyon County's Development Services Department (DSD), the office at 111 North 11th Avenue in Caldwell that administers Chapter 7, reviews site plans for compliance with the 85% cap when a commercial or industrial project applies for a certificate of zoning compliance. Because the limit is a hard percentage rather than a discretionary standard, DSD can measure compliance directly from a site plan's impervious-surface calculations.

This section governs only unincorporated Canyon County land: it has no effect inside Caldwell, Nampa, Middleton, Greenleaf, Melba, Notus, Wilder, Parma or Star, each of which sets its own lot-coverage rule under its own municipal code.