The best Virginia retaining wall, in my opinion, is the smallest one you can build and still accomplish your goals. If you have to have a wall there are a lot of material options. Which one is right for you?
Wood
Pressure treated wood retaining walls are typically the least expensive way to go. The materials are fairly inexpensive, you don’t need to dig much of a footer, and once you get the bottom course or two in and leveled the wall goes up quickly. 6×6 pressure treated timbers are held together with either steel spikes or timberlok screws. At intervals you’ll extend timbers (called deadmen) perpendicular to the wall face into the hill. These act as a lever arm that helps keep the wall face from rotating forward. No one is ever going to gush over your beautiful wood wall, but it’s a reasonably attractive solution.
There are two big drawbacks to a wood wall. From a design perspective, you’re limited to straight lines. Timbers come in 8 ft lengths. While you could technically cut timbers into a bunch of smaller segments to make a curve, it wouldn’t be particularly strong and you still wouldn’t have a smooth curve,
The other drawback is longevity. Pressure treating delays rot. It doesn’t prevent it. As a general rule, we tell people to expect a 10-15 year lifespan for pressure treated wood wall. There are still wood walls from the 80s and 90s out there but back then, they used arsenic in the treatment process. Modern walls use copper, which is serviceable but doesn’t seem to hold up nearly as well. If you’re only going to be in the home 10 years, or you’re willing to create a potential project for Future You, a pressure treated wood wall can be a way to save a few dollars.
Segmental Retaining Walls
Segmental retaining wall blocks are typically made by paver manufacturers. They’re made of concrete and are designed to lock together as a system to hold back the grade. Lighter duty segmental retaining wall (SRW) blocks may be glued together with specialized adhesives. The ones that we use for serious walls interlock with pins and are tied into the ground behind the wall with geogrid. The geogrid is a critical part of SRWs because that is what prevents the wall from rotating forward under load.
Segmental retaining walls work well in a variety of situations. Unlike wood walls, you can integrate curves for greater design flexibility. Depending on the particular block and the site conditions, you can build a fairly tall wall (just be sure to work with a structural engineer!). SRW block options have come a long way since I started doing this. While they will never look exactly like stone, SRWs can actually make a great design statement on their own. I actually prefer the retaining walls that embrace the fact they are NOT real stone, like Techo-Bloc’s Graphix wall.
One drawback is cost. SRW block can get expensive, especially for the more decorative styles. An additional cost is engineering. In a lot of counties you can design and build your Virginia retaining wall based off their “Typical Retaining Wall Details” packet with wood or masonry walls. Because there are so many different segmental wall blocks out there, most counties don’t have a typical detail for the SRW system you want to use. This means any wall 3 ft or higher needs the services of a structural engineer.
The other disadvantage of segmental retaining walls is that you need enough room behind the wall for excavation to install the appropriate geogrid. The taller the wall, the farther back you’ll need to dig. This can present an issue if you’re building a wall along the property line or close to a structure.
Segmental Retaining Walls – Gravity Walls
For situations where we can’t excavate far enough for traditional SRWs, there are gravity walls. These wall blocks are massive, starting at 2 ft x 2 ft x 3 ft and going up from there. The idea is that the wall has enough mass on its own to resist the forces behind it. Gravity wall blocks are more expensive than traditional SRW blocks and require heavy equipment to install. However, you have less excavation and backfill to worry about so you do save on that.
Like traditional SRWs, segmental gravity walls have gotten a lot more attractive over the years. Manufacturers like Redi-Rock offer a wide range of options, and Techo-Bloc offers their Skyscraper block .
Drystacked Fieldstone
If you like the look of stone it’s hard to beat a drystacked fieldstone wall! You can create beautiful curves and integrate boulders and other items like millstones to create a one of a kind wall.
In terms of cost, we’re usually slightly more expensive than a comparable segmental retaining wall. The limiting factor with drystacked walls is height. At 3 ft or less, they’re a great and honestly cost effective solution.
Masonry Options for Virginia Retaining Walls
Masonry retaining walls are the most complicated to build. We dig down 2 ft and pour a frost footer with concrete and rebar, and then we either build up with concrete block (CMUs) or form and pour a concrete wall. The advantage to a masonry wall is that you can make it look like whatever you want. You can veneer it with stone, with brick, or even tile. You can create curves or you can build a straight wall.
As far as Virginia retaining wall options go, masonry walls are generally the most expensive option. They also require the most skill on the part of the wall builder.
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