Building a Rock Wall | Ask the Expert
In the middle of the 19th century, when America was still a farming nation, more than 250,000 miles of stone walls coursed through New England and New York. Over the last 40 years, starting with his family’s business and now on his own, Kevin Gardner has rebuilt some of that old fencing. “For me,” he says, “the old walls are connected to an explicit former world that looked, felt, and operated very differently from our own.” The work isn’t easy, of course, but if you’ve got the patience, a strong back, and a few key tools (a spade and a couple of iron bars), Gardner says, it’s doable.
The Right Stuff
Good material isn’t cheap; a pallet of weathered granite can cost as much as $800. But there’s another option: Owners of woods where old crumbling walls reside, out of sight, might be willing to sell the stone. (Keep in mind that we’re not advocating stripping existing walls that are sturdy.) “Speak to your local road agent,” Gardner suggests. “He generally knows what the landscape is like,” and can tell you whom to talk to. Another option: Purchase cheaper granite riprap (about $15 a ton) for the interior of the wall, and expensive stuff for the facing.
Good Ground Game
Prepare the ground by digging a hole with the spade. If you’re rock-free, keep digging to create a trench to run under the length of your eventual wall. Make it 1.5 feet deep and fill it with crushed granite. This will give your wall a sturdy base. “An enemy of walls is their own weight,” Gardner explains. “It compresses the ground beneath relentlessly over time.” If the ground is already strewn with rocks, skip the trench. “The ground won’t compress that much,” Gardner notes.
A wall’s stability comes from its first layer of stone. Gardner says a good rule to follow is one in which the width of the retainer is three-quarters the height of the wall. If the structure is 6 feet tall, for example, the bottom layer of rock should extend out 4 feet. “I once worked on an old carriage house where the foundation walls were 8 feet high but their ‘footprint’ at the base was 12 feet wide,” Gardner says.
The Right Fit