Retaining Walls: East Honolulu vs Urban Honolulu
How do retaining walls rules compare between East Honolulu, HI and Urban Honolulu, HI?
Urban Honolulu has fewer restrictions than East Honolulu.
East Honolulu, HI
Honolulu County
East Honolulu retaining walls on Kuliouou, Hawaii Loa Ridge, and Niu Valley hillsides fall under ROH 21-4.40, which caps fill-bearing walls in required yards at 6 feet with terraced heights combined.
View full East Honolulu rules →Urban Honolulu, HI
Honolulu County
Urban Honolulu limits retaining walls that contain fill within required yards to 6 feet under ROH 21-4.40 and combines terraced wall heights to prevent stacking around hillside lots.
View full Urban Honolulu rules →Key Facts Comparison
| Fact | East Honolulu | Urban Honolulu |
|---|---|---|
| Yard max height | 6 feet | - |
| Terraced rule | Heights combined | - |
| Code section | ROH 21-4.40 | ROH 21-4.40 |
| Engineering trigger | Above 30 inches | - |
| Max height | - | 6 feet |
| Terracing rule | - | Combined height |
| Permit trigger | - | Over 30 inches |
Highlighted rows indicate differences between cities.
East Honolulu FAQ
How tall can a Hawaii Kai retaining wall be?
Walls containing fill in a required yard cap at 6 feet under ROH 21-4.40. Terraced walls are measured as combined height. Engineering review is required above the 30-inch permit threshold for hillside lots.
Do Kuliouou hillside walls need extra review?
Yes. Steep Kuliouou and Hawaii Loa Ridge sites typically require geotechnical and drainage review, engineered drawings, and sometimes grading permits under Chapter 14 alongside the 21-4.40 retaining wall rules.
Urban Honolulu FAQ
How tall can a retaining wall be in Urban Honolulu?
Under ROH 21-4.40, retaining walls containing fill within required yards cannot exceed 6 feet. Terraced walls on hillside lots in neighborhoods like Manoa are measured as one combined wall.
Does a hillside retaining wall need a permit in Honolulu?
Yes, if it exceeds 30 inches. ROH 18-3.1 exempts only walls 30 inches or shorter. Honolulu DPP typically requires engineered plans, drainage, and guardrails for larger hillside retaining walls.
Compare other topics
See how East Honolulu and Urban Honolulu compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool