The Purpose of Retaining Walls

Retaining walls are used to contain soil and manage water run-off for the prevention of hillside erosion and slips. It is important that retaining walls are appropriately designed for their location as they must withstand significant pressure and a failing wall can cause a lot damage.

There are many different systems used for retaining walls.

Gabion Basket

Low cost and easy to build, Gabion basket retaining walls are an attractive option. They are constructed of rocks wrapped in strong wire mesh baskets and stacked together.

Crib Wall

Crib walls are made up of a series of interlocking beams, creating a hollow space which is filled with soil and rock and all held in place by gravity.

This type of retaining wall has been around for a long time and while they can be constructed from timber, they are most commonly made from prefabricated concrete blocks.

The way crib walls are constructed makes them ideal for planting and they can look very pleasing to the eye.

Timber Wall

Timber retaining walls are the most common. They use strong wooden posts buried deep in the ground with cross beams to contain the hillside.

Post-quake checks

Many retaining walls were damaged in the Christchurch earthquakes – it is important that they are checked and properly repaired to ensure they don’t pose a safety risk.

The Christchurch City Council has more info here.

Retaining walls and building consents

Retaining walls less than 1.5m high do not require a building consent if they:

  • include a ground water drainage system
  • do not support any additional weight such as vehicles or buildings

It the retaining wall is more than 1.5m high and/or supporting additional weight it will require a building consent before construction can begin.

Contact Backyard Projects to discuss your retaining wall needs today.

Gabion basket

Gabion basket retaining wall built by Backyard Projects

Example of a crib wall

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