Ada County, ID Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Ada County, ID, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Convertible spaces
- Garage, basement, accessory bldg
- Must meet
- Section 8-4-23 standards
- Building code
- Ada County Title 7, Ch. 2
- Parking
- Required for both units
- Code section
- Ada County 8-4-23(E)
Summary
Unincorporated Ada County lets you convert an existing garage, basement, or detached accessory structure into a secondary dwelling, provided it meets the Section 8-4-23 standards, the Ada County Building Code, plumbing and electrical codes, and off-street parking for both units.
An existing garage, basement or a detached accessory structure may be converted into a secondary dwelling, provided that the conversion or structure meets the standards of this Section, along with all applicable requirements of the Ada County Building Code.
Full Breakdown
Ada County Code Section 8-4-23(E) allows an existing garage, basement, or detached accessory structure to be converted into a secondary dwelling if the conversion meets all Section 8-4-23 requirements plus the Ada County Building Code (Title 7, Chapter 2), any applicable plumbing and electrical codes, and off-street parking for both the principal and secondary dwellings. The converted unit must have separate kitchen and bath, its own entrance and address, utilities, and a recorded deed restriction. It counts as the one permitted additional dwelling on the lot. An accessory structure otherwise may not be used as a dwelling except through this secondary-dwelling path. Inside cities, city conversion rules apply.
Violations & Fines
Converting a garage or basement into living space without meeting Section 8-4-23 and building-code requirements is a zoning and building violation subject to Development Services enforcement.
Frequently Asked Questions
Can I convert my garage into a living unit in unincorporated Ada County?
Does a converted garage need extra parking?
Sources & Official References
Other rules in Ada County
Compare Ada County to another location·View the Idaho accessory structures overview
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