Retaining Walls: Mililani Mauka vs Pearl City
How do retaining walls rules compare between Mililani Mauka, HI and Pearl City, HI?
Mililani Mauka and Pearl City have similar restriction levels.
Mililani Mauka, HI
Honolulu County
ROH Sec. 21-4.40 limits fill-retaining walls in Mililani Mauka yards to six feet and combines terraced wall heights, important on the community's sloped Central Oahu grades.
View full Mililani Mauka rules →Pearl City, HI
Honolulu County
Pearl City retaining walls on the Pearl City Highlands and Manana hillsides fall under ROH 21-4.40, capping fill-bearing walls in required yards at 6 feet and combining terraced heights.
View full Pearl City rules →Key Facts Comparison
| Fact | Mililani Mauka | Pearl City |
|---|---|---|
| - | - | |
| Yard max height | - | 6 feet |
| Terraced rule | - | Heights combined |
| Code section | - | ROH 21-4.40 |
| Drainage review | - | Chapter 14 |
Highlighted rows indicate differences between cities.
Mililani Mauka FAQ
Can I build a three-tier terrace instead of one tall wall?
Terraced walls are measured together under ROH 21-4.40, so stacking tiers does not sidestep the six-foot limit.
Must retaining wall finishes be approved by MTA?
Yes. Walls visible from the street typically require MTA approval for color and finish.
Pearl City FAQ
How tall can a Pearl City retaining wall be?
Walls with fill in a required yard cap at 6 feet under ROH 21-4.40. Terraced walls are measured as combined height, and engineering review is required above the 30-inch permit threshold on hillside lots.
Do hillside walls need extra review?
Yes. Pearl City Highlands and Manana hillside sites typically require geotechnical and drainage review, engineered drawings, and Chapter 14 grading coordination alongside the 21-4.40 retaining wall rules.
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