Retaining Walls: Kailua vs Waipahu
How do retaining walls rules compare between Kailua, HI and Waipahu, HI?
Kailua and Waipahu have similar restriction levels.
Kailua, HI
Honolulu County
Retaining walls in Kailua follow ROH Sec. 21-4.40, which caps fill-retention walls within required yards at 6 feet. Terraced walls count toward combined height totals, and most walls over 30 inches require engineering.
View full Kailua 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 | Kailua | Waipahu |
|---|---|---|
| - | - | |
| Yard max height | - | 6 feet |
| Terraced rule | - | Heights combined |
| Code section | - | ROH 21-4.40 |
| Drainage overlay | - | Chapter 14 |
Highlighted rows indicate differences between cities.
Kailua FAQ
Can I build a 5-foot retaining wall in my side yard?
Yes, up to 6 feet within required yards under ROH 21-4.40, but you will likely need a permit and engineering over 30 inches.
What about two stacked 4-foot walls?
Terraced walls are typically measured together, so two closely spaced 4-foot walls may be treated as an 8-foot wall exceeding the cap.
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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