Dry-Laid Retaining Walls: What They Are and Why We Use Them

The Greater Cincinnati area is full of hills, valleys, and other changes in topography, and Our Land Organics frequently utilizes retaining walls in our Design/Build work to maximize usable space in our clients’ yards and gardens. Retaining walls are an excellent way to transform a treacherous slope into a flat area that can be used for vegetable production, patio space, or even a driveway.

Each year manufacturers offer new concrete products for retaining wall construction, but we love building retaining walls using natural stone and dry-laid construction practices. In this blog post, we’ll share some of the reasons we love dry-laid retaining walls and answer some of the questions we get about these types of retaining walls.

A dry-laid retaining wall installation in progress. (Our Land Organics design and installation)

What Is a Dry-Laid Retaining Wall?

Put simply, dry-laid construction is a time-tested method of building stone fences, walls, and even houses without the use of mortar. When done properly, dry-laid construction utilizes gravity and friction to create durable and long-lasting structures.

Dry-laid construction is an ancient building method that requires a high level of skill to install. It’s waned in popularity as more and more landscape companies utilize modular concrete blocks, but we believe in the enduring value of craftsmanship.

Dry-laid construction is still heavily employed in regions like the UK, Scotland, Ireland, and certain areas of Kentucky where farmers build dry-laid fences out of fieldstone to keep livestock contained.

In addition to their beauty and cultural richness, dry-laid retaining walls have a few distinct advantages over their mortared/modular counterparts:

Water Drainage
Mortared walls and modular walls prevent water from flowing through them, creating an incredible amount of hydrostatic pressure behind the walls that can contribute to failure if their complex drainage systems do not function properly.

Dry-laid walls, on the other hand, allow water to drain through them via natural weep holes and crevices between the stones. This makes them much less susceptible to failure due to hydrostatic pressure.

Adaptability
Because dry-laid walls get their strength from stone-on-stone contact and gravity, they can withstand slight foundation settling or disturbance. These walls are designed to “bend so as not to break” and have even been observed to survive minor earthquakes.

Ease of Repair
Other than a handful of stone-shaping tools, a knowledgeable stonemason does not need specialized equipment or material to build or repair dry-laid walls. This, coupled with the availability of natural stone, makes construction and repair of dry-laid walls a cost-effective undertaking compared to their more engineered counterparts.

Ecology
Dry-laid walls create homes for a vast array of beneficial insects, reptiles, and plant life. Because of their ability to reflect sunlight and store water in their natural crevices, dry-laid walls are a favored spot for many ecologically valuable salamanders, lizards, and snakes.

Sustainability
The process of creating and transporting concrete products contributes massive amounts of carbon to the atmosphere. One study showed that each pound of concrete releases nearly one pound of carbon dioxide into the atmosphere. Comparatively, natural stone is ubiquitous, often available on site or mined locally without the use of carbon-pumping kilns.

What Makes Dry-Laid Walls Strong?

For those unfamiliar with dry-laid construction, it can be difficult to understand where their strength and durability comes from. There are, however, a couple key factors of design and construction that contribute to the strength and longevity of a dry-laid retaining wall. We’ll go into a few of nitty-gritty details here.

Foundation Course
Our dry-laid walls feature a wide foundation course that is wider than the rest of the wall, dispersing the weight of the wall and minimizing the risk of foundation settlement.

Batter
If you’ve ever seen a crumbled dry-laid wall, you’ve probably seen it tumble forward, seemingly pushed over by the hillside. Our dry-laid walls are built with a calculated batter or slope into the hillside. For every 6 inches up we build, we slope 1 inch into the hillside, bracing the wall against lateral pressure created by the freeze-thaw cycle and minimizing the risk of failure.

Tie Stones
At regular intervals, we place tie stones that span the entire width of the wall and extend into the hillside itself. These tie stones bind the wall together and create extra stability throughout.

Friction
During the construction process, each stone is placed so as to maximize surface contact with the stones above and below it. This surface tension, combined with gravity and the weight of the wall, is an incredibly strong binding force that prevents sections of the wall from slipping, settling, or failing.

Dry-laid construction is an ancient and endlessly rewarding practice. It’s an exercise in patience, craftsmanship, and problem solving. When done correctly, it creates results that are remarkably durable and resistant to a host of natural pressures. If you’re considering incorporating a retaining wall into your landscape, consider reaching out to us to learn more about our dry-laid retaining walls.