Retaining walls

Unreinforced retaining wall.
Unreinforced retaining wall that collapsed in an earthquake

Are your retaining walls in good order?


In hilly areas, timber or concrete retaining walls hold back earth on a slope or at a change of level. If these are damaged in an earthquake, it can allow the land to slump and slide behind them.

To check

  • Looking at the retaining wall from one end, is the wall positioned correctly, eg standing upright or leaning slightly into the slope?
  • Is there any missing timber or concrete?
  • Are there any cracks or signs of damage?


Ask a chartered professional engineer for advice before repairing or replacing a retaining wall.

If you build a retaining wall more than 1.5m high, you need a building consent.

A retaining wall that has buildings or car parks or a road just above it, also needs a building consent.