Building with Native Stone

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Dimensions

T he more width you build into your wall per unit of height, the bigger its footprint, and the more stable it will be. So dig your trench a good bit wider than the base of the wall and make it as deep as you can manage. I plan the footing base of my own walls to be about one and a half times their width at ground level, with a gradual upward slope from base to grade (the bottom of the trench to the top). I try to build each face sloping inward at about a 15-degree angle, called batter, from base to top (see Fig. 2).

The batter lets gravity pull the wall in on itself as well as straight down on each individual stone. No wall builder sticks to a single, strict height-to-width ratio, of course, and often as not, the availability of rock and the use to be made of the wall will determine your dimensions. Few rocks, and the need for a high screen, make for a thin, well-thought-out wall; lots of rock, and no need at all, produce nothing but a rock pile. Most of the massive New England stone walls that surround our place were raised mainly as somewhere orderly to stash an oversupply of glacial erratics—which were jutting out of the hayfield, just waiting to chip a scythe blade at mowing time—so they're good and wide. They also defined property lines. Many real estate deeds contain such language as ". . . 20-1/3 chains running 67.5 degrees along a stone wall from a large Chestnut, thence 62 feet to a blighted Elm, thence 115 yards 57.3 degrees along a loose stone fence . . .", and so forth. Today, only the stone walls remain, sad to say.

Laying Out

N ext, find a length of twine and some stakes, and lay out your wall. Be sure to line the stakes straight and don't skimp on them. Too few stakes and a high wind can bow out your string, and you'll end up with an unwanted curve in your wall (see Fig. 3).

If you plan a wall more than a few feet high, you may want to make genuine batter boards, lengths of lumber fixed to a ground-level board at the desired angle of batter Use them repeatedly, much as a carpenter uses the square, to check the angle of what's being built. A mason's level is sometimes helpful in setting individual stones, particularly at the top course and when leveling out stone tables, benches, and such wall furniture as gates and steps.

Always keep your guide string perfectly horizontal (use a hardware store line level —shown in Fig. 3—for this), because you'll use it to align the layers or courses of rock in your wall, raising the line as you build. Level courses are not essential on flat ground, and are hard to maintain precisely on any terrain if you're working with a lot of irregular stones. In Fig 4, for instance, oddball, giant, and partly buried boulders made flat courses almost impossible . . . but it's a good wall nonetheless.

Still, you will want to try to keep your layers horizontal ( straight ), particularly on rolling ground, just to keep gravity pulling straight down (see Fig. 5). If you slope the courses going over a rise, in time the wall will sag downhill.

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