What factors affect the pricing of a retaining wall installation?
When it comes to understanding what the investment is when installing a retaining wall, there are several factors to consider. We have seen many clients over the years not truly understand the pricing of pavers because there is not enough educational information online that factors in all the protentional elements that contribute to the final price. Generic national websites often miss the key factors, so being mindful of square foot pricing or the industry average is a great starting point, but often does not reflect the true price of a patio.
Material
The type of material that is used does play an effect on the end price of your project. Different manufactures have different products that vary drastically in price. The low end of modular retaining wall block is around $8 per square foot and the high end can be $55 per square foot (+/-). On average, the most commonly used block falls somewhere around the $10-$20 per square foot price. Outside of modular block, which is the most common type of wall we see, other materials used include boulders, cinder block with veneer, poured in place concrete, as well as gabion block. Due to the wide range of material options available, material choice does play a large factor in the overall price of a job.
What is pre-existing
The process of site prep for installing a retaining wall does vary depending on the conditions that are pre-existing. For example, a retaining wall that is to be installed in an area that has no pre-existing wall compared to an area that has a pre-existing wall requires two very different preparation practices. The more demo and site prep needed to perform before a single block can be laid will result in an increase overall price. Factors to consider are disposal costs, specialty equipment rentals, labor costs, and trucking fees.
Type of installation practice
There are several different types of installation practices when it comes to how contractors install retaining walls. The biggest factor that affects the installation practice is the type of material being used. For example, a modular block retaining wall compared to a poured in place concrete wall has two very different installation practices. The difference in installation practice has different installation times, specialty equipment needed, etc. Being mindful of the type of installation practice being performed on your property is essential to analyzing the true cost of what an installed wall will cost.
Engineering
Depending on the overall height of the proposed retaining wall, it may require engineering. Typically, any wall over 4’ in height would require engineering documents in order to obtain the necessary township building approvals. Engineers do charge for their services which would add to the overall project cost. Also, depending on the site conditions, type of material being used, and height of the wall, the engineer may require specific building requirements to be installed when constructing the wall. For example, the engineer may require additional blocks to be buried to have a deeper footer, have more tightly laid geo grid lengths to disperse the weight of the wall, or require weekly on-site inspections to monitor the progress of the wall.
Vehicular applications
If a retaining wall is being built to support a vehicular load (weight), an engineer may require specific installation practices or building specifications to be met in to withstand the weight over time. Vehicular applications are treated separately from non-vehicular retaining wall installations due to the increase in weight the wall needs to account for.
Access
How simple or difficult it is for crews and machines to access the work location will play effect into the overall price of a retaining wall installation. If the crew must go around to the back of the home several hundred feet, with only being able to use a wheelbarrow and no machines, this is yet another factor that plays effect on the overall price. On the flip side, if a machine can be used in the same example, or instead of going all the way to the backyard, the work location is several feet from the driveway, this would greatly increase efficiency when installing the project which can help reduce cost.
Number of cuts
When installing a retaining wall, depending on the material being used, they are modular units, that need to be altered to contour to curves. The additional time and material wasted performing custom cuts in a wall installation does play an effect on the overall cost of a job. If a wall is rounded compared to straight or have a 90-degree corner(s), it would require additional time to cut each of the pavers to match the requested shape. Also, when cutting all the block, the cut portions are thrown out since they can’t be reused. This does result in additional material needed to be ordered to account for the increase in waste. A more efficient installation of a retaining wall does require more straight lines which would result in fewer cuts and less waste.
All in all, the factors listed above are the most considered elements that affect the overall price when installing a retaining wall. There can be additional factors that can affect price since each job is unique, hence the reason for not having a standard square foot price. Square foot pricing is great for giving ballpark estimates to set expectation of what a project could cost. Always keep an open mind when talking about price since there are several factors that can fluctuate the overall final project price. Asking your contractors to elaborate more on each of these factors can help you get a better idea of why the project may cost what is does.