Building a better retaining wall can be the difference between a beautiful and safe landscape space and a hazardous eyesore.
Retaining walls offer many benefits when carefully planned and well-constructed. For the gardener, they provide easy access to a place to plant flowers, shrubs, or vegetables. For people who live in an uneven landscape, the wall acts as a barrier against soil overwhelming their patios, driveways, or play areas. They also prevent soil erosion, limit flooding, and—when done right—beautify the landscape.
But when older or poorly built retaining walls fail, the resulting mess is not only an eyesore, but presents safety hazards as well. When homeowners in the St. Louis area come to us with this problem, we are happy to help.
Needing a Better Retaining Wall
Last fall, a man with a failing wood tie retaining wall contacted us. He wanted a new wall that would accentuate the beauty of his home and protect his outdoor living area. We visited the site and talked with him about what he wanted. Once we were sure we understood his requests, we provided a free estimate and detailed drawings. We also pointed out that we’d have to dig up part of his patio in order to do the job correctly. Our plans and estimate impressed him, and he agreed that a new patio would look great next to his new retaining wall.
Once we were sure he was happy with the plans, we got the required permits and went to work!
Choosing the Block and the Pavers
The homeowner chose a segmented wall made of weathered standard, 6-inch concrete Romanstone Versa-lok with matching 4-inch caps. This is an excellent choice, and not just because it’s attractive. Segmented walls make a better retaining wall because they are dry stacked, mortarless, and interlock with pins. They don’t require frost footings, which means we don’t have to excavate below the frostline in order to keep them from shifting when the soil freezes and expands. When correctly constructed, a segmented wall will stand for many years with minimal maintenance.
For the patio, they selected Romanstone Chatham multi-piece pavers and a 4×8 slate Holland stone border. This is also an excellent choice. We specialize in green paver installations because it benefits both the homeowner and the environment. And Chathams are beautiful, earth-friendly, permeable pavers that handle water run-off like champs.
Clearing the Way
We began by removing the vegetation and soil from behind the old retaining wall and disposing of the old wooden ties. This gave us a clean slate to work with.
Then we excavated a wide 125-foot-long trench, digging down a few inches below where we wanted the base of our wall to be. Then we ran a piece of machinery called a vibrating plate compactor back and forth through our trench until it compressed the soil. This provided a solid foundation that will not shift beneath our structure or the supporting gravel substrate.
Protecting the Investment through Better Drainage
Water is both a blessing and a curse for landscapers. A blessing because it gives us a lovely landscape. A curse because it can be hard on structures like retaining walls, hardscaped paths, and patios.
Effective drainage is important. When building retaining walls, Big Bend Landscaping combines compacted, crushed rock as backfill with a length of socked, perforated SDR 35, PVC to create a French drain. This prevents hydrostatic stress. That is, it prevents water-logged soil from pressing against the width and depth of the wall. Over time, this can cause the wall to lean or bulge and eventually become unstable.
We set our first layer of blocks on a base of compacted gravel, and added the PVC drain plate to the trench behind it, taking care to make sure the ends were clear of the substrate to ensure easy drainage. We surrounded the pipe with a layer of gravel, compacted it, and added the first length of geogrid. Using Versa-lok pins, we anchored the blocks and moved on to the first visible row.
Building the Retaining Wall
Part of the beauty of working with Versa-lok blocks is how easy it is to secure them against the wear and tear of time, weather, and shifting soil. Each row of blocks is affixed with pins that are driven through pre-drilled holes into the holes in the blocks below.
Versa-lok blocks are also designed to work with geogrid, a geosynthetic material that looks a bit like a fishing net, but is much heavier. We place one end between each row of blocks while securing the other with metal rods that are driven into the soil behind the compressed rock. Geogrid reinforces each layer of substrate and supports the structure of the wall. In brief, Versa-lok makes full use of the benefits of gravity.
Except for the length of PVC, we repeated each action, applying layers of compacted rock between lengths of geogrid. Along the way, we secured each row of blocks with Versa-lok pins. When the wall reached the desired height, we backfilled the top row with a high-quality top soil and secured the caps.
The finished result—a better retaining wall—is impressive. And that wall will be there for many years.
Building the Patio
We began the patio by excavating the yard, making sure to level and compress the work area in order to achieve the best results.
Afterward, we added the compacted rock base. The rock base provides a porous space that helps with drainage and a stable foundation. After we poured the rock, we used a plate compactor to level and compact the foundation.
After the rock was properly compacted, we added a few inches of sand. This keeps the pavers from shifting around once put in place. To make sure it was level, we used screed guides. And as the last step before adding the pavers, we placed stable edge restraints around the outer edges to prevent any lateral movement.
We then installed the pavers. Multi-piece Chatham pavers look great, whether laid in a random design or a pattern. This large patio lends itself well to a random design.
After finishing the pavers, we added the 4 x 8 border. Borders serve as both a frame for the pavers and as a definitive border against which homeowners can landscape or plant foliage.
As a final step, we sprinkled a thin layer of sand and went back over the patio with a vibrating plate compactor to aid in settling the pavers into place.
The Final Results
The finished results pleased everyone; us and—most importantly—the homeowner. They now have a nice 125-foot-long wall with 325 square feet of block, backed by 30 tons of back-fill. It’s complimented by a 700 square foot patio resting on 22 tons of compacted rock. Both of which they will enjoy for many years to come.
Conclusion
Big Bend Landscaping has been delivering premium landscaping services to the St. Louis area for over twenty-five years. We build: firepits, retaining walls, hardscaped paths, outdoor living areas, and outdoor kitchens. When you combine your vision with our know-how, there are no limits to what we can do!
Big Bend Landscaping has a Level 1 Certification from the National Concrete and Masonry Association. This means we’ve received extensive training in how best to provide you with quality installations and materials.
We offer a one-year warranty on everything we do, and this includes the materials and labor. While we expect our work to remain solidly beautiful for many years, if there is a problem, all you have to do is reach out to us.
Live in or near St. Louis and are ready for that outdoor living space you’ve always wanted? Give us a call – 636) 349-2946 – or contact us for an online estimate! Let us help you design the outdoor space you’ve been dreaming of!