DIY Rock Wall Saves Money

Build functional rock walls with rocks you collect.

Backdrop for a dramatic planting

Rock walls provide backdrops for dramatic plantings.

Jerry Pavia

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Carl Dill grew up in the lumber business but fell in love with stone. For more than two decades he’s been turning granite, schist and bluestone into dry-stack rock walls around New Milford, Connecticut.

Instead of mortar, dry-stack building uses friction and gravity to hold stone structures in place. “It’s a hobby, a wonderful hobby,” says Dill, who recently retired from the building supply business. And if it’s something you might enjoy, too, Dill advises, “Get started. It’s not rocket science; it just takes practice.”

Dill’s “practice” began when he bought a stone house in need of repair. After fixing his home, he headed outdoors, where his first efforts at wall building proved less than stellar. Seeing the results, he figured, “Maybe I ought to do this the right way.”

Trial and error turned him into an expert. To date, he’s built about 25 walls for himself, his friends and his church that he feels confident will stand the test of time. Stone feels right, he says. “It just seems so permanent and reassuring.”

In New England, Dill notes a growing interest in preserving and constructing stone walls. As developers began bulldozing these historic structures, citizens rallied for the structures’ protection. At the same time, people began wanting walls of their own. Doing the work yourself brings satisfaction, says Dill. Plus, “having people build it is not cheap, about $100 a face foot.”

Wall-building classes that Dill teaches at the local college fill fast. Most students are middle aged, and about a third are women who typically want a garden wall.

Large projects or small dry-stack walls serve all sorts of needs. Historically, they marked boundaries or provided an artistic way to use excess stone. Landscape designer Darren Owen uses stone in abundance. “It’s beautiful; it’s durable.” And, he says, “It’s a more natural way to deal with the landscape.” For his own home in Lawrence, Kansas, he constructed a series of stone retaining walls, topping them with trees and plants to cut noise. Steps and pathways add movement.

When it comes to walls, Owen and Dill lean in different directions. Single walls work best with land that has topography to it, or where you want to create a terrace, Owen says. They can prevent erosion, enclose gardens and add privacy. He specializes in retaining walls.

Dill, on the other hand, enjoys freestanding walls; basically, two walls back to back, slanting slightly toward each other. 

Two Walls, Back to Back

A freestanding wall follows the same basic rules.

As Carl Dill notes, you are essentially building two walls back to back, slanting slightly toward each other, the inside filled with less desirable stones. For this structure, the standard slant (batter) is 1 inch for every 12 inches of height. This lean will tighten your wall as frost heaves it upward. Make sure that the top of every face and end stone tips slightly inward.

Dill adds:

Use a mason line held in place by short stakes to outline length and width. Dig this area 3 inches deep. Spread 2 inches of gravel in the trench and then start your wall. Rearrange the gravel to accommodate any odd configurations on the bottom so the stones set solidly in the trench fit tightly side by side.

Don’t build on frozen ground because, when it thaws, your stones will settle unevenly. Also, avoid building too close to trees so the roots don’t interfere with your wall.

Arrange stones into four groups. Group One, the largest stones, will form the base. Rearrange gravel to accommodate any odd configurations so that stones fit snugly side by side. Group Two, face stones, have desirable sides that will show. Group Three, the fill stones, go inside the wall. Hide Group Four from yourself so you won’t be tempted to use them in a pinch. You will need these large, flat, attractive stones for the ends and top.

As you build, obey the Cardinal Rule: “1 over 2 and 2 over 1,” meaning that any face, end or top stone must cover the joint of the stones below it. Eliminating vertical seams strengthens your wall.

Start building one end up a few courses, then move to the other end. Next, work toward the middle. Drive stakes about 6 feet apart along the outline of the wall. Connect them with a mason line at the proposed height of the wall and attach a line level. This will keep the wall straight and level.

To finish, arrange capstones, keeping seams as tight as possible and filling voids with smaller stones. Put small amounts of stone dust over the seams and brush it in. Pack the dust down. After the first rain, go back and refill where the stone dust has settled into the wall. This step prevents leaves, seeds and debris from working into the wall and forming soil where trees and brush will grow, their roots forcing the stones apart and collapsing the wall.

For more details, visit the website at www.Stonewall.UConn.edu/BuildBuilding.htm. 

Selecting your stone

For either project, one of your biggest decisions will be selecting stone.

Granite and mica schist abound in New England while limestone dominates Kentucky and the Midwest. There’s agate, shale, quartz, sandstone, slate and granite. Some come basically flat; some come chunky or rounded.

Dill loves granite. “It’s hard to work with, but it’s beautiful,” he says. With his walls, he likes to mix things up. “People often want their stretch of wall to all look the same. To me, that’s not really interesting.” Listening to lively Irish music, he blends stone and color with easy abandon.

Owen works primarily with local limestone. Pick the hardest you can find or you’ll face problems with flaking and breaking, he says.

Natural rock from your own land is an obvious first choice. When buying, find where the product comes from and don’t purchase strip-mined stone, says Robert Thorson, director of The Stone Wall Initiative in Storrs, Connecticut.

One option is purchasing fresh stone from an active quarry. Excavation in bedrock or glacial soils can provide materials for a stone wall, too, Thorson says. The Big Dig in Boston, for example, produced boulders that were later used for walls. To find a local quarry, check the yellow pages in the phone book or search the Internet for your town’s name and “quarry.”

Regional stone blends with its surroundings and is typically less expensive. To determine how much you’ll need, multiply height by length by depth of your proposed project – then round up for good measure. 

Basic principles

Experts differ in their opinions on building dry-stack walls, but they agree on the basics. If you want your wall to last, build it no taller than 4 feet. If your slope is too large for this size of retaining wall, consider building more than one wall.

Check with local zoning and land-use regulations before getting started.

For supplies, you’ll need a brick hammer to knock off edges and tap stones solidly in place; a stone hammer and chisel to break larger stones; a shovel, rake and hoe; a garden hose or mason line; line level; and stakes. In addition to wall stones, you will need washed gravel and stone dust.

Before you start, consider these guiding principles:

Don’t be in a hurry. This is something you want to last.

Stay safe. Wear hard-toe boots, eye protection, leather gloves and a lifting belt. Lift with legs bent and back straight.

For best results, mix sizes of stones throughout your wall.

Get a feel for your medium. Natural fieldstone has some undulation to it; use a hammer to knock off sharp points. If you need to break a stone, score a line where you want the stone to break with hammer and chisel. Hit the chisel with moderate force and repeat several times until the stone breaks.

Step back frequently to see the big picture, Owen says. “You have to see where you are and where you want to be.” If you note a problem, fix it, even if it means redoing an entire course (row of stone).

Remain patient. Remember, you are working on a puzzle that revels in imperfection. 

Roll up your sleeves

A retaining wall is a good starting project.

● Lay out your stone in plain view, grouped by size and shape.

● Mark the outline of your wall. For a curved wall, Owen recommends a garden hose or spray paint. For a straight wall, use wood stakes and mason string.

● Dig a trench about 8 inches deep and about 3 inches wider than the base of your wall. (Base usually runs at least half as wide as height.)

● Fill the trench with crushed stone (Owen uses AB3, a compacting gravel) to about 4 inches from the top.

● Compact the gravel with a hand tamper or vibrating plate, adding a little water as you go. Make this base nice and level.

● Begin laying your courses. For the first course, select your heaviest stones, saving your best wide, flat stones for the top.

● As you build, the stone above should overlap with the stones below (like you would lay bricks). Place any long stones perpendicular to the face of the wall to anchor it to the bank.

● Fit stones snugly, tapping lightly with a hammer. Occasionally, you may need to break stones into wedge-shaped shims to fill gaps, or use crushed rock to level uneven stones.

● Backfill with gravel, tamping it down after completing each course.

● Set each course back about 1/2-inch, creating a continuous back-leaning face. As each stone tilts down toward the middle, gravity pulls the structure together.

● Taper ends back into the hill.

● Lay larger flat stones (capstones) on top to hold your wall in place and provide a finished look.

● Plant the soil being retained. This adds beauty and helps anchor your wall.

Carol Crupper is a writer from Lawrence, Kansas.