Dry Stack Retaining Wall
The Garden Home Retreat sits on a hill that slopes toward the Arkansas River. This feature of the landscape offers a breathtaking view, but also creates a challenge of controlling soil erosion when designing a garden.
When looking for a solution to this dilemma I simply followed the advice of English poet Alexander Pope and consulted the "genius of place."
Between the mid-19th and mid-20th centuries the land had been used as a farm and traces of the terraces built back then can still be seen today. These lines etched into the landscape gave me a series of contours to follow for building a series of dry stack retaining walls. This terracing creates broad sweeps of level ground, an elegant solution for gardening on a hillside.
I chose to use dry stack stone walls for their historic appeal and for a few practical reasons as well. Dry stack walls are built without mortar, the stones are stacked one on top of the other. This makes them naturally draining, which is important when using a wall to retain soil. There is no need to build a foundation below the frost line because the loose stones can shift slightly to accommodate frost heave. This flexibility also means the wall is not subject to frost damage. And best of all, the dry stack method is less expensive than mortar-based walls, which appeals to my frugal nature.
I chose Course Doctors out of Flat Rock, North Carolina to install the dry stack walls at the Garden Home Retreat. I had come into contact with this company while working on a local landscaping project. I got to know their team of experts first hand and was very pleased with their stone work. Their specialty is golf course construction and renovation, so I knew that the 425 feet of wall that I needed would be right up their alley.
Of course not all dry stack wall projects are this extensive. For smaller constructions the process is straightforward enough to do on your own, but there are a few things you should know before you get started.
- Dry stacked stone walls are usually constructed against a hillside. Though, freestanding walls are stable up to about 3 feet in height.
- Stone is sold by the ton on wooden pallets. The stone yard will offer delivery service if needed.
- When you order the stacking stone also purchase crushed stone for leveling your foundation trench and for filling in gaps. This material is also called stone screenings, stone dust or fines.
- There are 3 basic shapes of stone: round field stone, relatively flat stacking stones and uniformly cut dressed stone. Each shape will give you a different looking wall. Try to match the style of the stone with the style of your home and garden. For instance, a dressed stone wall is very formal and would be out of place in a rustic setting.
- Essential tools for the project: level, string, wooden stakes, long handled shovel, hammer, chisel, wheel barrow or garden cart, level, gloves.
- Useful tools to have on hand: back brace, knee pads, sledge hammer for large stones, tiller.
- Each layer of a dry stack wall is called a course.
- When putting your wall together mix the stone sizes throughout the wall rather than using only large stones at the bottom and small toward the top.
Here are the basic steps involved in building a dry stack stone wall.
- Draw the wall to scale and measure the length and height. Most stone walls are about 1 foot wide so when making your calculations you can assume this measurement. This step will help you calculate the amount of stone you will need.
- Visit a stone yard, select and order your stone.
- Measure and outline the wall using wooden stakes and string.
- Dig a trench of anywhere from 6 inches to 1 foot deep and 2 to 3 inches wider than the base of the wall.
- Fill the trench with crushed stone up to the soil line to create a level foundation.
- Lay one course at a time, fitting the stones closely together. Offset each course so that there are no large vertical spaces in the wall. Fill in gaps with crushed stone or dirt.
- Reserve an amount of large, very flat stones to use as capstones to top off the wall.
Good to Know: The Course Doctor's Expert Advice on Constructing a Dry Stack Wall.
- The choice of rock is very important. Angular, flat, stacking stones are much easier to work with than round field stones.
- For the long term stability cut your foundation trench into native soil rather than loose bedding soil. The native soil is less likely to move around or settle.
- For walls that are above 3 feet tall you want to create a 3 to 4 inch lean back into the soil. Do this by stacking each progressive layer about 1/2 an inch back. This will prevent the soil pressure behind the wall from pushing the stones out over time.