Hawaii's active hurricane season is exposing weak retaining walls and foundations, bad news for homeowners who put off repairs but a reminder that small cracks are worth checking now.

• Recent heavy rain and Kona lows have revealed structural damage on homes across Oahu.
• One badly damaged wall is close to collapse and needs a full engineering redesign before repairs begin.
• A retaining wall in Central Oahu fell down hours before crews arrived, near a school, showing how little warning there can be.
• Small cracks are often the only visible sign, so early inspection is the difference between a repair and a collapse.

Outlook: Another storm system could reach Hawaii by the end of the coming weekend, so homeowners with visible cracks should get them looked at now.