Most of the work of building a retaining wall is in choosing the right stones.
Stone Primer (Storey Publishing, 2007), by Charles McRaven, presents basic techniques of stonework and dozens of projects for inspiration and practical guidance. Designs for the home include structural masonry and accents like fireplaces and countertops, while landscaping uses include retaining walls, stone bridges, and even stone sheds and water features. The following project is from chapter 4, “Drystone Walls.”
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A drystone retaining wall is cheaper and easier to build than a mortared wall, having no footing or mortared joints. It isn’t as strong as a mortared wall, but, when built properly, can support a slope. The drystone retaining wall is more natural-looking, especially when built of aged stones rather than those freshly quarried or dug from the ground. Also, moisture seeping from the soil bank held by the wall will allow lichens and mosses to grow better on the drystone wall.
1. Start the retaining wall with stones 12 inches deep, set against the earth bank. This layer, or course, can be any height but would typically be about 6 inches. Fit the stones so they’re tight at the face, and fill any spaces up against the bank with soil, tamping it firmly. This first course is a good place to use stones that have rough faces, since these can be turned down and the soil dug out to fit. Reset the layout string to keep the front faces of the stones even and straight.
2. The second and succeeding courses of stone should be level and the faces plumb. Use increasingly deeper stones for each level, so that each stone lies on the ones below, with some of it extending onto packed soil at the back. Avoid running joints.
In keeping the face of the wall plumb, you’re actually leaning the wall into the hill, holding it in place. Because each stone also slopes slightly into the bank, any frost-induced movement will be countered by gravity.
3. The top course — the capstones — should be the full 24 inches wide (front to back) for stability. Choose these carefully and use wedges of stone to seat these solidly, because they’ll get walked on. They can be any thickness, but being large, choose thin ones so you can handle the weight; 2–3 inches is about right.
Excerpted from: Stone Primer © Charles McRaven. Illustration by © Michael Gellatly. Used with permission of Storey Publishing. Buy this book from our store: Stone Primer.
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