Maui County, HI Accessory Structures: ADU Rules (2026)

Chapter 19.35 of the Maui County Code governs accessory dwellings, and Ordinance 5966, adopted March 20, 2026, rewrote the floor-area section and retitled it. Section 19.35.020 now caps the gross covered floor area by lot area: 720 square feet on a lot up to 21,779 square feet, 840 square feet from 21,780 to 43,559, 960 square feet from 43,560 to 87,119, and 1,200 square feet on a lot of 87,120 square feet or more.

Covered floor area counts covered storage and covered walkways or landings up to four feet wide under eaves or overhangs that are not part of an uncovered open deck, patio, lanai, or similar structure. It excludes carports, parking spaces, and garages, along with areas inside them that hold laundry facilities and utility equipment such as water heaters. That exclusion matters when you size a unit, because a garage bay or a laundry nook in the carport does not eat into the cap.

Section 19.35.050 limits the number of units. On Maui island, no more than one accessory dwelling is permitted on a lot under 7,500 square feet, and no more than two on a lot of 7,500 square feet or greater. On Molokai and Lāna‘i, one accessory dwelling is permitted on a lot of 7,500 square feet or greater.

Section 19.35.010 requires a building permit for anyone who builds or otherwise establishes an accessory dwelling. The zoning district or state land use district still applies, except for its limit on the number of dwelling units per lot, and where a district provision conflicts with chapter 19.35 the accessory dwelling provisions prevail. The chapter applies in every zoning district that allows accessory dwellings.