Retaining Walls: Pearl City vs Waipahu
How do retaining walls rules compare between Pearl City, HI and Waipahu, HI?
Pearl City and Waipahu have similar restriction levels.
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 →Waipahu, HI
Honolulu County
Waipahu retaining walls fall under ROH 21-4.40, capping fill-bearing walls in required yards at 6 feet with terraced heights combined, impacting stream-side and hillside plantation lots.
View full Waipahu rules →Key Facts Comparison
| Fact | Pearl City | Waipahu |
|---|---|---|
| Yard max height | 6 feet | 6 feet |
| Terraced rule | Heights combined | Heights combined |
| Code section | ROH 21-4.40 | ROH 21-4.40 |
| Drainage review | Chapter 14 | - |
| Drainage overlay | - | Chapter 14 |
Highlighted rows indicate differences between cities.
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.
Waipahu FAQ
How tall can a Waipahu 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. Engineering review is required above the 30-inch permit threshold for taller installations.
Do old rock walls still comply?
Many legacy plantation-era rock walls are grandfathered. However, substantial alteration, repair, or replacement triggers current ROH 21-4.40 standards and may require engineered drawings plus drainage review.
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