Accessory Structures in Boise, ID (2026)
9 verified accessory structures rules for Boise, Idaho, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Boise allows one ADU (attached or detached) on every single-family lot. Idaho Code Section 67-6511A (2023) limits cities from banning ADUs in single-family zones. Boise permits ADUs up to 900 sq ft with streamlined review.
Accessory Structures: Adu Rules
Few RestrictionsADU Permits
Boise permits Accessory Dwelling Units by right on every single-family lot under the modernized Zoning Code Title 11 (effective December 2023). Idaho Code §67-6511A (enacted 2023) prohibits cities from banning ADUs in single-family residential zones. Boise allows ADUs up to 900 sq ft (or up to 10 percent of lot area) with streamlined administrative review through Planning and Development Services.
Boise ADU Permits (Zoning Code Title 11 + Idaho Code §67-6511A)
Few RestrictionsADU Impact Fees
Boise charges impact fees on new dwelling units including ADUs under the authority of the Idaho Development Impact Fee Act (Idaho Code §67-8201 et seq.). Police, fire, and parks impact fees apply; Idaho law strictly limits the categories and requires rational nexus and proportional cost recovery. Building permit fees and water/sewer connection fees through Boise Public Works also apply.
Boise ADU Impact Fees (Idaho Code §67-8201 et seq. — Limited Scope)
Some RestrictionsADU Owner Occupancy
Boise does not require owner-occupancy for ADU properties. Idaho Code §67-6511A (2023) prohibits cities from imposing owner-occupancy mandates that would make ADU construction impractical, placing Idaho among the most ADU-permissive states. Property owners may build an ADU on rental property, rent both units to separate tenants, or sell with the ADU intact. HOA covenants may still impose private restrictions.
Boise ADU Owner-Occupancy (Preempted by Idaho Code §67-6511A)
Few RestrictionsADU Rental Restrictions
Boise allows ADUs to be rented long-term without restriction and short-term with STR registration through the City Clerk. Idaho preempts municipal rent control and source-of-income discrimination protections. Idaho Code §55-208 (2017) prohibits cities from banning short-term rentals outright. Boise STR rules limit licensing requirements rather than prohibiting use.
Boise ADU Rental Restrictions (Long-Term Free; STR Registration Required)
Few RestrictionsShed Rules
Sheds 200 sq ft or smaller in Boise do not require a building permit but must meet zoning setback rules (typically 3 ft side/rear). Larger structures require a permit and must comply with lot coverage limits.
Accessory Structures: Shed Rules
Few RestrictionsGarage Conversions
Converting a garage to living space in Boise requires a building permit and full code compliance including egress, insulation, smoke alarms, and parking replacement. Garage conversions often qualify as ADUs under Idaho Code Section 67-6511A.
Accessory Structures: Garage Conversions
Some RestrictionsCarport Rules
Under Boise City Code Title 11 (Development Code), Section 11-06-07, a carport is an accessory structure, defined as a structure open on at least two sides used to house motor vehicles of the occupants. In residential zones, garage and carport openings facing a side street must sit at least 20 feet from the side-street lot line, and detached accessory structures cannot encroach into required front or street-side yards.
Carport Rules in Boise
Some RestrictionsTiny Homes
Boise recognizes tiny homes on foundations as ADUs under Idaho Code Section 67-6511A, typically capped at 900 sq ft. Tiny homes on wheels (RVs) are not permitted as permanent dwellings except in licensed RV parks.