How much does it cost to build a retaining wall?
Whether it is for reinforcement and the prevention of soil erosion, or purely decorative, a retaining wall requires special equipment, knowledge, materials, and skills which fall far outside of the average DIY enthusiast. For the purpose of this discussion we will consider the costs of building a retaining wall from cast concrete and at a length of 50 linear feet. We will also take into consideration various heights as well, ranging from six, eight and ten feet.
The average costs will include:
- Excavation - in addition to preparing the actual wall, the property owner is going to have to consider the excavation and site preparation required. Slope work is generally going to come in at higher costs than work located on a level surface, but according to the RSMeans cost calculation software, the following prices will apply:
- Clearing and grading of the plot - which tends to include brush and sod removal at a cost of $1800 per acre; and
- Materials - remembering that the project is going to require suitable backfill is essential and this will also have to be included in the costs of the project. This might include gravel and soil, or it could also mean the installation of drainage along with a gravel base and high-quality top soil. Costs will vary widely.
- The Wall - for a cast in place (concrete) retaining wall with a vertical face, installed on no more than a 33 degree slope with a level embankment, at 6' high (including excavation and backfill) the cost will be $12,800. When the wall is increased to 8' in height the cost will average at $13,700, and when the height is bumped up to 10' the cost increases to $19,900.
Additional considerations and costs
- Estimates and quotes - like many other major construction projects it is advisable to seek out estimates from a range of providers. Asking for references and going out to take a look at completed projects is a very wise decision. It is also a good idea to look at any walls following heavy rains in order to see if there is any trouble with drainage;
- The engineering - If the retaining wall is vital to the stability of a building lot it might also be necessary to seek the services of an engineer. This should not comprise any more than roughly 17% of any building project; and
- Dedicated DIY enthusiasts - if you are someone who is set on building a retaining wall, it is best to restrict the project to a very manageable size. For instance, something in the area of 20 linear feet at a height of 4' to 6' will be entirely possible. It will still require the same construction techniques, but it may be something that could use the more costly materials such as natural stone blocks, pressure treated lumber, and even bricks. Costs for this sort of project will remain lower than the professional installation with an average between $12 and $40 per linear foot.