Summary: How much does it cost to build a retaining wall, average cost of labour and average cost of materials.
It may seem to be quite straightforward; however retaining walls should not be underestimated. There are lots of considerations that should be taken into account and all of these will have an impact on the overall cost of your project. Retaining walls can prove to be the ideal solution for many garden landscapes and choosing the correct method of construction to suit your needs is very important. You will also have legal considerations and although it might seem like a small build in comparison to house extensions, you may still require planning permission, a permit and a completion certificate depending on the dimensions of your new wall. These are points that need to be thoroughly checked before any work is started in order to achieve a successful outcome.
Average Cost
| Job | Average Cost | Updated | Quote |
| Labour (m²) | £55 – £75 (m²) | 2019 | n/a |
| Materials (m²) | £45 – £55 (m²) | 2019 | n/a |
Factors to consider
Retaining walls can vary considerably in price and factors such as size. The method of construction and type of materials being used will figure highly when determining cost. If your retaining wall is not going to be too large, you may be able to save some money by doing lots of the labour and preparation yourself. Excavation will need to be done to allow for foundations. This may be something you might tackle yourself, however if your project is larger, you may need to factor in costs to cover the hire of heavy machinery. Having your supplies delivered is also something that people often take for granted, however if you don’t have suitable access to your garden (or to the section of garden that you are constructing the retaining wall), then you may well find that your costs will increase. Other factors to give some thought to concern drainage. This may be a requirement depending on what your wall will be retaining and, often overlooked is simply where you live as this can often play a major role weather wise, not to mention ground wise. Making sure that the top of your wall experiences the smallest lateral earth pressure is crucial. If this is not the case, the wall is likely to be unstable and vulnerable to movement which will completely defeat the purpose.
Costs to consider
There are a surprising amount of materials available which can be used to build a retaining wall and these include stone, wood, concrete, vinyl, brick, steel and other metals. Each of these materials will carry its own price and you should choose the material that will be most suited to your particular project, as well as providing you with the desired finished appearance. Previously, the popular choice was one-piece walls made from either concrete or wood, however most popular these days are individual segmental walls as not only are they cheaper and easier to work with, but they are also more environmentally friendly. As well as the main materials for your wall, you will also need materials such as crushed stones for packing out your initial trench and possibly for final grading. It is also likely that may need to backfill, so if you don’t already have a supply, you will also need to cost this into your budget. For walls which are likely to be over 3 feet tall, it would make sense to engage the professional services of a structural engineer, especially if your wall will be facing a main pedestrian walkway. Higher walls may need extra support anchors built, in which will ensure the wall is completely safe. This measure will also prevent your wall from collapse which, as well as being a disaster for obvious reasons, could also be a danger to family members and members of the public who may simply be passing by at the wrong time.
Retaining walls can be used in a number of different ways and can make nice garden features, but the secret of success with any retaining wall is to make sure that it is built properly. If you have seen retaining walls that are starting to crack or bulge, this is simply because the amount of weight they are supporting has not been property accounted for in the build. It is so important that retaining walls are not simply treated as a decorative addition to the garden but as a cleverly engineered structure which, if planned out, built and designed properly, will enhance your garden and last for many years.
Do your homework, plan your design, choose your materials, account for all potential hidden costs, obtain any necessary permits and, where appropriate, enlist the professional services of a structural engineer and you will be ready to start building.