Any good project starts with knowing how much material and time are necessary to get the job done. The need to know what to expect is especially true when undertaking a significant project, such as building a retaining wall.
Using a cost and material estimator online is your best, first choice to get accurate numbers. Such a calculator goes beyond the raw number of blocks needed. It also calculates material costs and, sometimes, even the cost of labor.
When I think back to my first retaining wall project, it’s a wonder I got it done. I threw the entire project together at the last minute.
I’ve come a long way since that humble beginning. People now call me regularly to do retaining wall projects. Even if I don’t build the wall, I can help the customer prepare.
For those of you doing a DIY retaining wall project, you have my respect. It doesn’t matter if they are large or small. A retaining wall project is challenging.
The project starts with knowing what you need and what to expect as it progresses. This article will help you through the process.
How To Calculate How Many Wall Blocks For A Retaining Wall
Building a retaining wall can be a challenging project. I expect to come up against something new every time I make a retaining wall. However, the process always starts with estimating the needed blocks for the project.
To estimate how many blocks are necessary for a retaining wall, you first must measure the length and width of the wall. Multiplying those numbers will give you the square footage. Calculate the square footage of a single block and then use this formula: L x W / Block Sq Ft = Number of Blocks.
You can do your calculations from scratch, but there are benefits to using an online estimating tool. It will go beyond the standard estimate and include other factors that will make a difference in the number of blocks needed.
The first step is getting an estimate of how many blocks you need. The next step is calculating other materials, such as the cap blocks, gravel, and tool rentals. Doing so will give you a clearer idea of the cost and scope of the project.
When doing this or any other DIY project, you should also calculate the cost of safety. Building a retaining wall is a big job with many hazards.
Wearing the appropriate PPE for the job is your first defense against injury. At a minimum, you should wear safety glasses, gloves, work boots, and long pants (no shorts).
Another important safety consideration is respiratory protection. When you cut blocks for the retaining wall, silica dust becomes respirable.
If you get silica dust in your lungs, it will not come out. It causes your lungs to harden over time and could lead to severe health conditions like cancer and silicosis.
Wear an N95 mask or a half-mask respirator when exposed to silica dust. You can also use a tool with water, such as a wet saw, to keep the dust to a minimum.
As we move down through this article, we will consider more than just the number of blocks you need for a retaining wall. We will consider the cost of both material and labor.
How To Calculate the Cost Of Retaining Wall Blocks
If you plan on building the retaining wall on your own, you need to calculate how much the blocks will cost. The formula to calculate the block price is simple, but you still have to do your research in advance.
The cost of material to build a retaining wall can cost anywhere from $15 to $30 per square foot. Some materials, such as natural stone, may cost even more.
To calculate the cost of retaining wall blocks, you will first calculate how much you will spend per square foot. Get the price and dimensions of a single block. Multiply the length (inches) /12 by the width (inches) /12. The result of that calculation is the square footage of a single bock.
Use the following math for your calculations:
Block square footage: (L (inches) / 12) x (W (inches) / 12) = Square footage per block
Cost per square foot: Block square footage x cost of block = Cost per square foot
Cost per retaining wall: L (wall) x W (wall) x Cost per square foot = Cost per project
Additional factors will impact how much you will be spending on the retaining wall blocks. The following should be kept in mind to get a more accurate estimate:
Overage: As a general recommendation, order at least 10% more blocks than needed. Doing so will allow for any mistakes or damaged material.
It is sometimes possible to return the unused blocks for a refund. Check with the location where they were purchased in advance to know. Otherwise, you might be stuck with some overage and have to dispose of it.
Cap Blocks: Stone retaining walls include a top row of wall caps. These additional blocks help finish the project and make it look complete. Wall caps also add support to the wall.
Wall caps are different from the other building blocks. Calculate the needed wall caps separately to get an accurate retaining wall cost. Some retaining wall estimators will include this calculation as part of the math.
Underground: Include any blocks below the ground when doing your calculations. Measuring only the blocks you see will result in a shortfall.
Copyright protected content owner: ReadyToDIY.com and was initially posted on January 15, 2023.
On most projects, the first course of blocks will be partially or entirely under the surface. If the wall is holding back significant weight, more blocks may be underground to add support.
How To Calculate Cost Of Retaining Wall Blocks Installation (Labor, Incidentals, Etc)
Let’s face it, building a retaining wall is hard work. I do it for a living, and I still struggle on occasion. There isn’t anything wrong with hiring a contractor, but what is the cost?
The labor for installing a retaining wall is approximately $15 per square foot. If you are building a higher retaining wall or a wall that requires additional engineering, the price will likely be higher to cover the cost of permits and additional labor.
It is also essential to consider the person or company installing the retaining wall. Hiring a contractor will be an added expense, but if the wall holds back a lot of weight, you don’t want to trust the job to a handyman.
A contractor charges more money for different reasons, including the following:
Insurance: The insurance a contractor carries can protect their business and the homeowner at the same time. It’s also an additional assurance that they are a legitimate company.
Experience: If you hire a contractor with experience, you will get a higher-quality job. Can a handyman handle the project? If the job is for landscaping is the only reason I would consider the use of a handyman.
Engineering and Prep: A contractor has connections to get the wall appropriately engineered. They also know how to prepare the ground for the wall. Their knowledge includes how deep to dig and what to use as backfill.
Choosing who will do the labor can be a challenging decision to make. It will impact more than the bottom line. Your choice of who will build the retaining wall will also affect the quality of the project.
Other Things To Consider When Estimating Retaining Wall Blocks Project
By this point, you should have a clear indication of what you need for your retaining wall project. Let’s move beyond the number and cost of blocks and look into other factors that affect the project.
Nothing is as it seems, and what may be on the surface will not be on the bottom line. That is also true of building a retaining wall. Here are some additional considerations that can affect the cost and schedule of the project.
Wall and Material Type: The type of wall you build and the material you use are not always a matter of personal preference. The purpose of the wall can impact the project.
An oversized wall holding back a lot of weight requires special engineering and building materials. The material and engineering can add to the bottom line.
Foundation: Any retaining wall needs a solid foundation. In some cases, the foundation will extend underground; in others, a foundation must be dug and poured.
Placement: Will the contractor have easy access to the wall location? Access can impact the project if they have to haul equipment and supplies into the area.
Copyright article owner is ReadyToDiy.com for this article. This post was first published on January 15, 2023.
Drainage: When you build a retaining wall on your property, you will affect how water drains. A larger retaining wall project may need extra engineering to ensure water drains correctly.
Permits: Some municipalities require a building permit before building a retaining wall. The AHJ might not require pulling a permit for a small landscaping wall, but a larger retaining wall is a different animal.
The formula for calculating the cost of a retaining wall is multiplying the length and width of the future wall, including any underground blocks. Multiply the square footage by the price per square foot of block to get the project’s overall cost.
Related Articles
Framing Cost Estimator / Calculator
Quartz Countertop Estimator / Calculator
ReadyToDIY is the owner of this article. This post was published on January 15, 2023.