Retaining walls are often given a bad rap. Yet they are both functional assets and decorative features within our gardens. Designed to be strong enough to hold a load of soil, as well as look attractive, they increase our outdoor usable space. As structural engineering plays a part in their construction, they are best left to expert tradespeople.
The main purpose of a retaining wall is to hold back a load of soil or earth. This happens when there is a change in the grade of the ground. Each wall must support the weight of the soil behind it, as well as on it.
Retaining walls need to let the water from behind drain freely.
A building consent is not needed for construction if the wall is less than 1.5m high and does not support anything other than the ground. If the wall needs to support additional load, such as a car or building and/or it is over 1.5m in height, building consent is required.
Depending on the type of soil and the weight of the load it is required to support, there are three main types of walls you can have built.
Traditionally retaining walls have been built with two types of materials: timber and masonry. Once again, the type of soil, the size of the wall and the load it is required to support can determine the materials to be used.
Cantilever walls requiring a T or L footing are usually made with concrete solid bricks or blocks, as well as timber. Gravity walls as either solid concrete or in the case of crib walls, hollow masonry blocks or pre-cut timber. Anchored walls often use a mixture of concrete, steel and timber.
If your land is sloped or rests near the edge of a slope, you may need to have a retaining wall built. This includes situations such as:
As retaining walls are structural features, hiring a professional builder or landscaper to install one is essential. If you need a wall but don’t know what type or if it needs building consent, our expert team of retaining wall specialists can help you out. Simply post your job here today and our local tradespeople will get in touch to give you a quote.