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– James Thurber
How to Build a Stone Wall That Will Stand the Test of Time
by Charles McRaven
How to Build a Stone Wall That Will Stand the Test of Time
It's a matter of making gravity and friction work for you--and finding the right stones.
By Charles McRaven
Gathering scattered stones and shaping them into walls goes back as far as private property, as far as fields, as far as the time when man had his first urge to build. And the technique has never changed. Few human labors surpass a weathered dry-stone wall for eloquent simplicity, beauty, and timelessness.
The first considerations in building a dry-stone wall are its location and its purpose. Stone walls serve as fences to keep livestock in or out, as borders to demarcate property, as retaining walls to hold banks of soil, or simply as logical places to collect unwanted stone. And they can be built almost anywhere. I've seen walls across swamps and on slopes that required hand holds to climb.
I'll be discussing how to lay up a freestanding wall, as opposed to a retaining wall, because the former is less technical in function and construction. First, let's consider the fundamental make-up of a well-built wall.
The Basic Structure
Only gravity and friction hold your wall together against the ravages of frost, tree roots, and burrowing animals; therefore, choosing the right stones is essential. The wall that's simply thrown together from a pile of cast-off stones won't stand for long. A dry-stone wall should have at least a two-stone thickness, with each side sloping inward against the other. Ideally, all the stones should be flat or wedge-shaped, but the only places I've found this ideal stone were in the sandstone-ledge country of north-west Arkansas and the Kentucky bluestone region. More typically I've had to work with New England granite boulders, Virginia graystone shards, and corroded Missouri limestone. Rougher, rounder rocks require more ingenuity, but your wall can still stand if you keep gravity and friction in mind.
The minimum thickness of the wall will depend on its desired height. It can be as thick as you like, but should always be at least three fourths as thick as it is tall. Thus a 4-foot wall should be 3 feet or more thick. That means two 18-inch stones sloping into each other at the center.
Of course there's more to it than that. All your stones won't be 18 inches wide. Or sloped. Or flat, top and bottom. And even if they were, if you simply laid them up side by side, you'd have essentially two walls divided down the center instead of a unified structure To tie the wall together, you need long tiestones, ideally 3 feet in length, to reach all the way across. Tiestones should be placed across every three layers or so, at random spacings of around 4 feet.
Again, you won't have neat, 3-foot stones for ties, so you'll have to use a combination, say a 30-inch stone that reaches across the center gap, and a 6-inch one to fill out the remaining space. And since your shorter stones won't be an even 18 inches either, the center joint won't always be at the center; you must tie across it with whatever stones will bridge the joint. Fit each stone so that it's solidly seated, even if that means wedging. Don't leave any outside stones wobbly or sloping downward; they'll eventually fall out. Small or odd-shaped stones can go into the center of the wall to fill spaces left by outside stones that are less than 18 inches long. Using smaller stones will create several joints, all of which tie-stones should span.
You now have the basic structure of the wall, and you should adhere to this pattern as closely as possible given the shapes and sizes of your stones. You'll find you must compromise continually, and each time you do, it weakens the wall just that much. But the ideal is unattainable, and in dry-stone work you do have enough margin that you can lay up an enduring wall with imperfect stones and other limiting factors.
Building the Wall
The actual building should begin by your making sure the base course, or layer, of stones slopes inward. I do this by digging a shallow, V-shaped trench for the wall down to firm subsoil. A trench results in less settling and frost heaving. I step the trench down or up a slope so that the wall is started on a level surface. If your stones in the first layer are about 3 inches thick, step the trench in 3-inch steps--more if the stones are thicker, which will mean a deeper trench.
If you're in a creek bottom with 5 feet of topsoil, don't dig that deep. Normally 5 to 6 inches will get the base stones to firm footing. Going below frost line is not necessary, because water can seep between the stones and freeze anyway. (A mortared stone wall on the other hand, should always start below the frost line, since any shifting will crack it.)
Thanks to the V-shaped trench, your wall is off to a good start. If you've had to use several chunks of stone (they can even be round) for the first layer, tie these down with a layer of flat stones. I usually strive for as level a top surface on each layer as possible, wedging to even out irregularities. Whatever you do, keep all top surfaces sloped inward. Tie-stones will leave surfaces that are roughly horizontal, and you must re-establish the inward slope in the next layer.
The stones in your wall are never quite still, what with freezing and thawing, a hot summer sun, growing tree roots, and burrowing animals. You must lay up the stones so that gravity pulls them back tightly in place after each minute movement. Friction will let you fudge a little, but not much. Wedging is absolutely necessary and must be done properly. Stones used for wedging should be as large as possible to support the weight of upper stones. Little chips tend to get crushed and to work out more easily. Even large wedge stones must be placed with strict attention to the inward slope, or of course they'll come unwedged.
You should try for a relatively even outer surface to the wall, which makes stone selection harder. Finding an 18-inch-wide, flat stone with a taper and a good outside edge is rare. So you compromise, keeping in mind that stability is the first priority. If the wall is well laid, it will look good even if the outsides are rough.
Most dry-stone builders stretch strings to keep their walls straight. You should certainly use a level, particularly if building on a hillside. I rarely use either, because I don't want wall building to be too much of a geometric exercise. I do, however, spend a lot of time standing back to sight along the wall as I go.
If your wall goes uphill or down you will have stepped the trench, and you should try to keep all the layers level lengthwise, which mean stepping the top of the wall, as well. In order to help shed water--which can get inside a wall, freeze, and push the stones apart--I like to use flat tie-stones on top, leaving each one shingle-fashion over the one next to it. On level ground you won't do this, but do try to butt the top stones as closely as possible to reduce the amount of rainwater that runs down into the wall. Another tip is to slope the flat top stones to one side just a little. Ideally, the top stones should have a taper so that they can sit as flat as the other tie-stones yet still shed water to the side. But, of course, flat, straight-edged, long, tapered top stones don't exist in quantity, except in fantasy.
You often begin and end a wall against something--a building, a stone ledge, or a bank of soil. Avoid trees, because their movement and growth will push the wall too much. Butt the wall against any vertical or sloped surface, again giving careful attention to stability. If the wall doesn't begin or end against anything else but is a freestanding structure, you'll need good square-ended stones to achieve a vertical face. That will mean you need stones with two sides or edges, at least, to form a 90-degree corner, and tie-stones with three such edges. Also, the lengths of end stones should vary so that you aren't left with a vertical crack after you begin the wall. A header over a stretcher is ideal, to use masonry terms. That means one end stone ties across; the next extends down the wall. When constructing a corner, make sure the two runs of wall interlock, again by using headers and stretchers. Take the time necessary to find the right stones here; they must fit tightly for the wall end or corner to be stable.
The same goes for the vertical ends where gates are mounted. Hanging a gate in a dry-stone wall is a challenge, because the weight and constant opening and closing tend to pull things apart. You might try wedging a long, flat hinge pintle between stones in the end of the wall, but that will work only if the pintle is pinned or bent behind stones vertically to hold it from pulling out. A better way to hang a gate is to use a star drill or masonry bit to drill holes in large, stable end stones, and then anchor eye bolts as half your hinge. Use lead anchors, since the plastic ones tend to disintegrate over time. The latch hardware can also be anchored in place, again to a large, solid stone. I prefer forged iron for gates, but rot-resistant wood (locust, cedar, cypress, redwood) or wood treated with a preservative will also serve.
I've talked a lot about properly shaped stones and their importance if your wall is to endure. Finding good stones will be difficult, time consuming, and perhaps expensive. You may shape stones to any degree, from chipping off offending corners to finished sculpture, but your wall loses some of its natural appearance with each visible fresh cut or break. I try to keep shaping to a minimum, and if possible I try to keep it hidden.
Tools for shaping are simple, having changed little in thousands of years. Most helpful will be a mason's hammer, also called a bricklayer's hammer, with a curved chisel edge opposite the flat striking face. Use it to chip edges, knock off corners, even break thin stones. A stone chisel is a wider version of the cold chisel, sometimes with a beveled edge, used where greater accuracy or force is necessary than the mason's hammer affords. Use a 2- to 4-pound striking hammer with the stone chisel to score a groove for breaking or to chip and break stones. A stone point is used for fine dressing, and you won't need it for most dry-stone-wall work. It's used for reducing a hump by striking right into it to remove stone a bit at a time. A stone point is the tool that leaves regular little pit marks in dressed stonework.
A large stone hammer is a sledgehammer with a blunt edge parallel to the handle, like a dull splitting maul. It can weigh as much as 30 pounds and is used to make several small stones out of one big one. Occasionally you may give up on placing a round stone in your wall and resort to bashing it into more accommodating pieces.
To chip edges, use a technique of chipping down and outward to lessen possible breaking elsewhere. Lay the stone in a bed of sand or wood shavings to cushion it while you work. To break a large stone in two, cushion it and start a line with the striking hammer and chisel, going over the stone with harder blows at each pass until it breaks. Or use the large stone hammer lightly in a line of blows, then harder. Always wear safety glasses when shaping stone. You'll find that a lot of chips will hit you in the shins, but that's not as dangerous as taking one in the eye.
Of course, you can build the entire wall without shaping a single stone if you can find the right stones. Most of the time spent in building with stones is in searching for the right rock, and it's worth every minute. Now that you know what goes into the building of a dry-stone wall, you're better prepared to go after the proper stones.
Finding and Hauling Stones
If the stones you need are close by, you can use a wheelbarrow to move them to the site. Use a good contractor's wheelbarrow, preferably one with a shallow pan to keep the center of gravity low. And load it with good bit of the weight back on the handles (contrary to what many newcomers to physical labor will tell you), so that you'll have control of the load. Putting the weight forward will bog down the wheel, and you'll have to work harder to push than if you're lifting part of the load. Garden carts aren't much good with stone. If one were sturdy enough for this work, it would weigh a ton when loaded.
If your stones are too far away to wheel home, consider a stoneboat. It can be of almost any design, but should be low, so that you don't ever have to lift the stones much, on or off. I roll stones onto a platform of 1-inch oak boards set on 2- by 6-inch oak runners on edge. I shoe each runner with 1/4- by 2-inch steel, attached with countersunk screws so that the shoe slides easier and lasts longer. This crude sled can be pulled by horse, tractor, or four-wheel-drive vehicle. The stoneboat I'm using now is only about 3 by 5 feet, but I carry as much stone as I want on it. It has no sides, but a 1-inch strip at each edge keeps the stones sloped inward just as they are in the dry-stone wall, and they ride easily.
If you have to go far afield for stones, you'll need a heavy trailer or a truck. I use a two-wheeled trailer built on an automotive rear axle, with six-ply tires and a heavy frame. I pull it with my Land Rover to get into places most pickup trucks can't go. The trailer also dumps, which eliminates one round of handling the stones.
A pickup truck will haul moderate quantities of stone. One layer covering a 6- by 8-foot truck bed can easily weigh a ton, so don't overload. Getting the load moving is often not as difficult as getting it stopped. I recommend a 3/4-ton as opposed to a 1/2-ton or lightweight pickup for stone, because bearings, axles, springs, and brakes are heavier on the larger truck. If you're hauling stone in hilly country, use a standard shift to gear down on hills, or you may fade your brakes out. That has happened to me.
You can have stone hauled via dump truck for a fee and save yourself a lot of work, but you'll still want to hand pick each stone, and it's better to hand load to cut down on breakage. Trying to build anything with stones chosen by someone else means a huge pile of leftovers that won't fit anywhere.
When you prospect for stones, take along a pry bar. A straight steel bar, say 3 feet long, with a chisel tip is fine. Pry the stones up to get a good look. Wear gloves, and watch for wasps and snakes.
Try to stick with stones you can handle yourself or with a helper. Always lift with legs bent and back straight, or your wall-building career will end suddenly. Anything more than 100 pounds should be handled with equipment. I use the lift bucket on my tractor for big stones, placing them onto the wall by sliding them out when the bucket is at the correct level, then using a pry bar to move the stones into place.
You may rig a lifting tripod of three strong 2-by-4s and a comealong to load heavy stones or to place them in your wall. Make sure a chain is securely around each stone before lifting, and keep your feet clear. Steel-toed boots are a must.
If you must buy stone, it's worth whatever you want to pay. I have never bought a rock in thirty-five years of dry-stone work, except for recycled cut stone. A quarry near our home here in central Virginia charges $55 a ton for fieldstone (you haul), which covers about 5 by 7 feet, one 6-inch layer thick. Farmers will often haul loads of fieldstone for around that price, too.
Most often that same farmer will be glad to let you pick rocks out of his pasture or woods for free, hoping you'll take them all. Or you can recycle a stone chimney or foundation. I avoid other stone walls and fences, because the quality of the stones usually isn't as good. Or if it is, the wall is probably in good shape right where it is, a tribute to some other craftsman's skill. Chimneys and foundations from fallen or burned houses, on the other hand, are good sources of stones.
Be sure to take all the time necessary to build your wall. Don't invite a hernia. Those stones will be there a long time, looking more beautiful as they age. Finally, keep in mind that building a dry-stone wall--lichened testimony to the toil that cleared the fields--will admit you to an ancient brotherhood of craftsmen whose work may last as long as anything in this world.
Charles McRaven is a writer, builder, and teacher. He builds and restores hewn-log houses. He has worked with stone for more than thirty years and is the author of several books including, Buiding with Stone, Building and Restoring the Hewn Log House, and Country Blacksmithing. Mr. McRaven can be reached at 804-973-4859.
This article originally appeared in the Country Journal. Reprinted with permission. For subscriptions call 800-829-3340.