Ada County, ID Accessory Structures: ADU Rental Restrictions (2026)

Subsection F of Section 8-4-23 requires a recorded deed restriction or covenant before the county will issue a certificate of occupancy or sign off on the final building permit inspection for any secondary attached or detached dwelling. That recorded document has to address four specific points listed in subsection F(1). First, the secondary dwelling can never be sold or owned separately from the principal dwelling; the two units stay tied to a single title. Second, the secondary dwelling may only be used as habitable living space for as long as the principal dwelling or the secondary dwelling is occupied by at least one person holding an ownership interest in the property.

Third, and most consequential for rental restrictions, the code spells out what happens the moment that ownership-based occupancy lapses: the secondary dwelling automatically becomes non-habitable space, shall not be used as a dwelling, and shall not be rented or leased for any purpose. There is no grace period or administrative waiver written into the text; the change in status is automatic. Fourth, the restriction has to bind every successor owner of the property for as long as the secondary dwelling physically exists, so a new buyer inherits the same occupancy-linked rental ban rather than resetting the clock.

Together with the continuous-occupancy standard in subsection B(3), this deed restriction is the mechanism the county actually uses to keep secondary dwellings from turning into standalone rental units or being sold off as a separate lot.