Urban Honolulu caps impervious surface at 75 percent of lot area for residential dwellings permitted after May 1, 2019, under ROH 21-3.70-1 to manage runoff into the city's storm drains.
ROH/LUO 21-3.70-1 sets residential development standards for Urban Honolulu, including the 75 percent impervious-surface cap that applies to dwellings permitted after May 1, 2019. The rule is especially significant in dense, flood-prone CDP neighborhoods like Moiliili, Waikiki, and McCully where stormwater overload can push into the Ala Wai Canal or back up into streets during heavy rain. Floor area ratio, parking, and accessory dwelling unit rules also live in this section. Driveways, patios, pool decks, and roofed accessory structures count toward the cap. Pervious pavers with approved drainage can earn partial credit. The standard works with ROH 21-4.30 setbacks and 21-4.60 heights to shape Urban Honolulu's building envelopes.
Exceeding the 75 percent impervious cap in Urban Honolulu can require removal of paving, conversion to pervious surfaces, daily fines, and denial of permits until runoff calculations and drainage plans are approved by Honolulu DPP.
Urban Honolulu, HI
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Urban Honolulu, HI
Urban Honolulu caps residential structures at 25 feet under ROH 21-4.60 with a 30-foot envelope plane, while Waikiki, Kakaako, and Ala Moana high-rise distri...
Urban Honolulu, HI
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Side-by-side rule comparisons with other cities in Honolulu County.
See how other cities in Honolulu County handle lot coverage limits.
See how Urban Honolulu's lot coverage limits rules stack up against other locations.
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