Accessory Structures in Honolulu County, HI (2026)

ROH § 21-5.50-3(a)(1)(A)-(B)

Accessory dwelling units are not permitted: (i) On zoning lots in planned development housing or cluster housing; or (ii) On zoning lots that are landlocked. The total floor area of an accessory dwelling unit must not exceed: (i) 500 square feet for zoning lots up to 4,999 square feet in area; or (ii) 1,000 square feet for zoning lots 5,000 square feet or more in area.

ROH § 21-5.50-3(a)(2)(A)(i)

The accessory dwelling unit may only be used for long-term residential occupancy and may not be used as a bed and breakfast home or transient vacation unit; (ii)   The deed restrictions lapse upon removal of the accessory dwelling unit; (iii)   All of the covenants are binding upon any and all heirs, successors, and assigns of the owners; and (iv)   Neither the owners nor the heirs, successors,...

ROH § 21-2.140-1(a)

(a) Carports and garages. (1) When located in a residential zoning district, a one-car or two-car carport or garage may encroach into required front or side yards, including those in special districts, only under the following conditions: (A) No other viable alternative site exists relative to the location of an existing dwelling ... legally constructed prior to October 22, 1986, or to the topo...

ROH § 21-2.140-1(n)

(n) Conversion of accessory structures. An existing, legally established accessory structure constructed before September 14, 2015*, in the country or residential district may be converted to an accessory dwelling unit and allowed to exceed the maximum floor area established by § 21-5.50-3(a), or be exempted from the off-street parking requirement established by § 21-6.20(a) and contained in Ta...