Accessory dwelling unit services — Urban Honolulu, HI

Last updated: September 24, 2026

What affects the price

Building an ADU involves several moving parts that shape your total investment. The final figure depends heavily on whether you choose a prefab unit or a custom build from the ground up. Site conditions are another major factor; if your property requires extensive grading, utility trenching, or foundation work, costs will climb. You also have to consider your choice of finishes, like high-end appliances or custom cabinetry. Navigating local permit fees and impact assessments also adds to the total.

About this service

These services cover the end-to-end process of adding a secondary home to your property. This includes initial zoning checks, architectural design, permit filing, and final construction. You need these services when you want to create a separate living space for family, guests, or as a rental unit, but don’t want to manage the complex legal and structural requirements on your own.

Frequently asked in Urban Honolulu

Also serving nearby: San Francisco · Daly City · San Mateo · Salinas · Santa Maria

All cities in Hawaii →

More on this: HUD ADU resources — ADU policy and financing research.

Service area details

Serving all of Urban Honolulu — population 341,778; about 5,637 residents per square mile across 60.6 sq mi.

Neighborhoods served in Urban Honolulu: Kapahulu, Kaimuki, Manoa, Diamond Head, Makiki, Nuʻuanu — and every surrounding area.