There’s no sugar-coating it: Building a retaining wall and steps like these is a big project. In my case it involved removing an old poured-concrete wall and steps and moving a lot of heavy materials, including dirt, compactable gravel, sand and 80-pound blocks. But although the work was physically challenging, it wasn’t as complicated as you might think.
Like most successful projects, this one starts with a good design. I’ve designed and built several retaining walls, patios and paths, but this project combined all three and added the complicating factor of a steep 7-ft.-high slope, so I sought help. A wall higher than 4 ft. requires additional structural reinforcement and should be designed by a professional who understands the structural engineering requirements. I sketched out a basic plan and then handed it over to Villa Landscapes, the design division of the landscape center where I planned to buy my materials, for completion.
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The steps and the walls of this project are constructed from Versa-Lok standard blocks. We chose these blocks for multiple reasons. First, Versa-Lok provides many detailed drawings and thorough instructions on the company’s Web site. Second, the blocks use a pin system that makes alignment easy and results in a very strong wall. And finally, it’s surprisingly easy to build steps with these blocks. Once the base is formed, all you do is stack the blocks. Called the “base pedestal” installation method, it’s similar to building a pyramid. Several blocks are buried and seemingly wasted under the surface, but you’re trading the cost of those blocks for the time you save and potential errors you avoid by not having to compact and level multiple tiers.
Machines are essential to a job of this scale. A mini-excavator and skid-steer loader finished in one day what would have required a week of hard labor from two people to accomplish; their rental was money well spent. If you don’t have a place on your property to put the extra dirt, you’ll need to hire a dump truck to haul it away.
Because we had a professional design and Versa-Lok’s excellent installation instructions and drawings, we could have tackled the construction ourselves. But recognizing the value of experience, we hired installers at Highstone Landscapes Inc. to show us how the pros work and teach us a few tricks of the trade.
Watch a VIDEO slideshow overview of the retaining wall project.
Building the Retaining Wall
“The key to building any retaining wall or steps is getting the elevations [for the base pads] correct – the rest is just stacking blocks,” says Highstone’s owner, Jay Meyer. The bottom of the steps and the bottom wall are both built on the same level pad. We dug down approximately 10 in. below the grade in front of the wall and 4 ft. into the slope behind the wall so we could install the geogrid wall-reinforcement mesh. We also had to dig approximately 9 ft. into the slope for the steps. Make measurements as you excavate to check that your depths and layout are accurate. You must install the pad materials on undisturbed or compacted soil. If you dig a little too deep, do not replace the dirt. Instead, use more base materials to bring the pad up to final grade.
After the excavation is complete, drive stakes into the ground in several locations along the wall layout to establish the compacted pad elevation. Pound in the stakes, checking them with a surveyor’s level, until the top of each stake is at the final compacted gravel elevation. Lay down landscape fabric and compacted gravel until the pad is level at the final base elevation. The accuracy of the base pad is critical, so take your time to make the compacted pad level and smooth. Next, place two 1-in.-o.d. pipes on the compacted base and dump a layer of fine material such as sand over the pipes and base. The crew from Highstone prefers to use a driveway trap material instead of sand. Screed the fine material across the pipes to leave an even 1-in.-deep layer. Remove the pipes and carefully fill in the pipe tracks with more fine material.
Place the bottom course of blocks on the base material. Check each block to make sure that the top is level, and use a straightedge to align the back edges. Install the second course of blocks, staggering them so that the vertical seams do not align. The 3/4-in. setback distance is easy to maintain with the Versa-Lok wall blocks because pins connect and align with the course. The pins fit through holes in the top block and into a channel in the bottom block. Use a string line to align the back edges of each course. Backfill behind the blocks after each course is installed.
You must use alternating half blocks to build outside corners. We built one outside corner at the return wall (the wall section that turns 90 degrees back into the hill). The half blocks are broken rather than cut to create a rough face that matches the other exposed block faces. The corner blocks are secured with concrete adhesive.
We installed the first layer of geogrid on top of the third block course. Place the geogrid on top of the wall, making sure that it overlaps the pin channels. Then lay the next course of wall blocks. We installed another layer of geogrid on top of the sixth course of block. Backfill and compact the soil behind the wall as you install each course.
Providing a path for water to drain from behind the wall is critical to prevent potential damage caused by water pressure and water freezing behind the wall. Drain tile (perforated flexible drain pipe) provides the path for water to drain from behind the wall. We installed a drain-tile grate between two blocks in the third course. Then we graded the backfill behind the wall to slope down toward the grate. Lay the drain tile behind the wall and connect it to the grate with a coupling.
We built the upper wall following the same process that we used to build the lower wall. The upper wall is located behind the lower wall at a distance that is twice the height of the lower wall. The upper-wall blocks are connected to the lower return wall. The base elevation of the upper wall was determined by the elevation of the lower return wall. We excavated to a level so that the upper-wall blocks would match the elevation of the return-wall blocks.
Building the Steps
We used the same Versa-Lok wall blocks to build the steps as we used to build the wall. As with constructing the wall, the most important aspect is to first create a level base pad at the proper elevation. Once the base material was installed, building the steps basically involved stacking up a lot of blocks – a job that was laborious but not complicated.
The steps and walls in our project are connected, but you can also use this system to build steps without any walls. For example, this type of step construction would work well for the steps and stoop on the front of a house.
The bottom course of step blocks is the most important. The layout must be accurate, and the tops of the bottom-course blocks must be level and flush. In our case, the front row of the bottom-step course is a continuation of the bottom-wall course, and the return wall is the right side of the steps. We created the 44-in.-wide steps by placing two blocks facing forward and one block turned sideways to make the width of the steps.
The front edge of each course is set back 11 in. from the previous course. Each course of blocks is secured using concrete adhesive. Brush the tops of the block clean before applying the adhesive and placing blocks on top. Even a tiny pebble left under a block can prevent a good fit and cause the next block to rock.
The left side of the steps is partially exposed. The blocks for the left side are turned sideways to expose the front cut face of the block. The front block of the exposed side must be cut in half so that there is a rough face that matches the other front-face blocks – similar to an outside wall corner.
We capped the steps with bullnose pavers. You could also use wall cap blocks, but we preferred the round face of the pavers. We secured the caps with concrete adhesive and aligned them with a straightedge.
The landing and path at the top of the steps are made with pavers. The process is the same as building a patio. A gravel base is leveled and compacted and topped with a 1-in.-deep layer of leveled sand or other fine material so that the top of the pavers is flush with the top of the top step.
Though it was a lot of work, the finished project adds curb appeal and function that will last for many years – certainly worth a few days of heavy lifting.