Materials, Methods, Values
An enduring legacy, quarried locally
TYPES OF STONE
Flagstone
Our flagstone comes from Crab Orchard, at the top of the Cumberland Plateau in Tennessee. This is a sedimentary sandstone, formed when the region was covered by a warm, shallow sea over three hundred million years ago, and the textures and colors of this stone are a visual record of that period. Most surfaces are fairly smooth, but others preserve ripple-marks or even fossilized plants and animals.
There are three varieties: grey, buff, and variegated. The first two have a moderate range of tones. Variegated Crab Orchard is the best known and, depending on the deposit being quarried, can be mottled or striated, with striking colors ranging from off-white and tan to pink, red, and dark brown.
Flagstone comes in a range of thicknesses. The thinnest is suitable only for mortared work, and the stones are typically smaller. All of our dry-laid patios and walkways use stones between two and three inches thick. The grey is a harder stone than variegated or buff, and yields pieces with the largest footprint. We use grey Crab Orchard most often.
Fieldstone and Boulders
We use three different types of fieldstone. Much of it is sandstone from the Valley and Ridge province of eastern Tennessee. These stones range from grey to grey-brown. It is a fairly easy stone to shape with hammer and chisel and lends itself to tighter joints and a neater look overall. There is a considerable range in size. The boulders from this region range from weathered, mossy giants to blocky specimens ideal for a primitive bench or a boulder wall and smaller ones for garden borders and the like.
Doggett Mountain, at the northern end of Leicester, yields a coarse-grained, predominantly grey granitic gneiss with brown tones. This stone is more difficult to shape with a hammer and chisel, so walls and other features using Doggett stone will have a more rustic look, with looser joints and a rougher texture.
Hoopers Creek, in Fletcher, is the source of another granitic stone, formed in layers which yield stones of fairly uniform dimensions. A pale green mineral appears on occasional faces. This stone lends itself to stacking for walls. Some use it for patios and walkways, but its surfaces are generally too uneven, in our opinion, for this application.
Western North Carolina is home to a type of schist used in many older walls. It is not much in favor for building because of its extreme irregularity; the texture which causes this irregularity also makes it notoriously hard to shape without causing hairline fractures and unanticipated breaks. But for restoration work on existing older walls, and for those who appreciate local flavor and a very rustic look, this stone is a great choice.
Gravel
We use sharp grey granite gravel underneath patios and as a supplement to the structural heartstone behind walls. It provides good drainage, and pea gravel in particular is an excellent leveling agent for very large pieces of flagstone. Decorative gravel, dredged from waterways in the region, includes a variety of colors and sizes, depending on the source, and is ideal for rock gardens and paths.
METHODS
Dry stonemasonry relies on a handful of inviolable, common-sense rules for structural integrity. Rain will run behind and under walls and patios, for example; the earth must be contoured to drain it away. The stones of any retaining wall have to slope back into the earth behind them, so that gravity strengthens rather than weakens, and the top of each stone must slope back as well. Dead men must anchor the wall, and there should be no running joints. Heartstone must be used. There are only a few others.
The practice is eons old and has been handed down from one generation of masons to the next for as long. It has also been studied by engineers since at least the 19th century, when John Burgoyne constructed four stone walls and chronicled the causes of failure or stability. Many other studies have been conducted since then, and under most circumstances the structural superiority of dry stone walls to mortared ones has been definitively established.
Dry stonework can be built to last well over a thousand years, like the so-called Cyclopean walls of the Mycenean world. Such a wall is not often called for within city limits, however. Many venerable stone walls and houses have been demolished to make way for new construction during Asheville’s boom.
But our work is built to last many generations. It adheres to the same principles used by British masons in the early 19th century whose walls have supported an ever-increasing weight load from trucks and cars on the roadways of rural Britain. The structures we build will be enjoyed for hundreds of years to come. And, if you want stonework surviving into the next millennium, we can build it.
First, we make sure that the subgrade supporting our work is good, clay-rich, dense soil which will shed water and not settle. We are accustomed to moving very large stones into a site without the aid of a machine, where there is a risk of damage to tree roots or excavator access is simply not possible, using sturdy wooden ramps, rollers made from PVC pipe or wooden dowels, and other primitive tech.
We shape and dress stones using hammers and chisels to ensure a maximum of surface contact between them. Heartstone is carefully fitted behind walls for drainage and added stability, and those walls batter (i.e. slope) gently back. We do not use landscape fabric or other plastics behind our stonework; such materials are unnecessary in a well-built wall. Flagstone for patios is carefully examined for irregularities and sloped to prevent standing water.
VALUES
Stones are so commonplace, and their uses across global industry and trade so countless, that they are easy to ignore. But they were forged in cataclysms of fire and water and intense pressure hundreds of millions of years in the past. When we scrape our knees on gravel, skip stones in a creek, shovel rip-rap into a ditch, or build a dry stone wall, we are touching the most ancient material on earth.
Roan Mountain, for example, at the northern edge of western North Carolina, is known for its hornblende gneiss and similar metamorphic stone. At one billion eight hundred million years of age, these stones were formed during the series of tectonic collisions that created Nuna, the planet’s first supercontinent. The air was methane then, the only life anaerobic bacteria. The stones of Roan Mountain were silent witnesses to the first mass extinction, when these bacteria killed themselves by releasing critical amounts of their own waste product, oxygen, into the atmosphere, and paved the way for new forms of life.
Roan Mountain is not quarried. Other gneisses, however, are sawed for stone cladding, or pulverized to create construction aggregate for asphalt pavement. We respect stone and we care about how it is used. Stonemasonry often involves chiseling or grinding stone into desired shapes. Shaping by hand, however, involves getting to know each and every stone—its form, texture, strengths and weak points—and preserves more of its character.
For these same reasons we rarely do mortared work. The kilns involved in cement production need a great deal of thermal energy, and the industry increasingly relies on “secondary fuels” such as used tires, spent solvents, waste oils, and plastics to boost the heat provided by coal, petroleum coke, natural gas, and oil. Retaining walls and similar structures made with mortar do not generally last as long as their competently dry-stacked equivalents anyway.
However, there are times when a client’s needs or the conditions on site require it, and in those cases we work carefully to make sure that our use of mortar adheres to best practices. Mortar is made with the minimum required amount of water for increased strength, and applied judiciously. We believe that right action matters, and we strive to act in concert with the world around us.