Educational Resources

Learn about Hawai'i ADU regulations, permitting, and zoning requirements by island.

Hawai'i ADU Laws

Hawai'i has progressive ADU legislation that allows homeowners to build accessory dwelling units on their properties. ADUs are defined as separate living quarters on a residential lot.

  • ADUs are allowed on single-family residential lots
  • Both attached and detached ADUs are permitted
  • ADUs can be rented or used for family members

Size & Design Requirements

ADUs must meet specific size and design standards to comply with Hawai'i regulations.

  • Maximum size: 1,000 sq ft (or 50% of main house)
  • Minimum lot size varies by county
  • Must maintain architectural compatibility

Parking & Setback Requirements

ADUs have specific parking and setback requirements that vary by location.

  • Parking requirements may be waived in some areas
  • Setbacks typically 5-15 feet from property lines
  • Check local county requirements

Utility & Infrastructure

ADUs must have independent utility connections and meet building codes.

  • Separate water and sewer connections required
  • Must meet current electrical codes
  • Stormwater management required

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