Limestone is one of the most commonly used stones in the building industry. When the stone creates exteriors such as the one on this home, it's not hard to see why.
Photo courtesy of Indiana Limestone Company

By K.K. Snyder

For hundreds of years, thousands of types of stone have been quarried around the world from beds formed over millions of years. Obviously, some types of natural stone are superior to others, especially when being considered as a product for building. When it comes to beauty, workability and structural integrity, limestone often is a favored material among architects, builders and owners.

A rock of sedimentary origin, limestone is composed of calcium carbonate or calcium and magnesium, or a combination of these. With natural characteristics such as fossils and shell formations, calcite streaks or spots, pit holes, open texture streaks, honeycomb formations, iron spots and others, limestone has a varied appearance and texture lending even more versatility as a building material.

Bonded through millions of years of heat and pressure, limestone varies in hardness and is commonly found in colors including black, grey, white, yellow and brown. Recrystalized, limestone becomes marble — another natural stone popular with building projects that normally is more costly than limestone. But it is pure limestone that often is chosen as an exterior commercial or residential building material for ornate features of grand — and not so grand — structures. Its virtually maintenance-free characteristic is a huge selling point for many builders.

Because it is virtually maintenance-free, limestone is a solid choice for exteriors near landscaping.
Photo courtesy of Indiana Limestone Company

Versatility Abounds
"Limestone is one of the [most common] stones used in the building industry. It has the ability to be worked very easily. It tools very, very well, so obviously you can make it very ornate," says Joe Vinci, owner of Vinci Stone in Maryland, where he started visiting at age 12 the company started by his father and his uncle.

Noting the high number of ornate limestone buildings in Washington, D.C., Vinci said the workability of the stone makes it a favorite in the industry. "They can be sawn easily and can be split on a hydraulic guillotine so it's not a real expensive product to produce. And because it's less abrasive than sandstone and the softer material when compared to granite, it's a good choice for making ornamental features."

Genuine limestone weathers naturally, without the use of sealers. Photo courtesy of Indiana Limestone Company

Limestone weathers naturally over time and its color mellows and blends into a pleasing, natural patina. With no artificial coloring agents to fade and no reinforcement rods to rust, the appearance of limestone actually improves with age, according to the Natural Stone Council (NSC).

"[Indiana limestone] tends to range in color, and with our stone the colors tend to mellow out over time," says Jim Owens, executive director of the Indiana Limestone Institute. He notes that moisture in the stone upon excavation causes variations in color, which change over time. "The stone tends to blend into a pleasing match, a more uniform match. Those varied colors will likely not be nearly as pronounced."

Coloring agents used in some building products have a tendency to fade over time, whereas limestone, with no coloring agents and strength enough to be used without reinforcement rods, does not. "Another positive of genuine stone is that it weathers naturally without the use of sealers," Owens adds.

In spite of limestone's affordability and ready supply, some people choose to purchase instead any number of cheaper, manmade cast products on the market manufactured to mimic limestone, adds Vinci, who operates three quarries, including one of the oldest, continuously operating quarries in the country.

Limestone exhibits no preferential direction of splitting and can be cut and carved in a wide variety of shapes and sizes. Thus, it can be sawed, planed, turned on a lathe or hand worked to match the requirements of demanding architectural designs, states the NSC's Web site. Limestone has proven its use from simple treads and pavers to landscaping structures and bridges, to soaring cathedrals over and over again.

Pavers, such as those surrounding this pool, are a popular way to incorporate limestone into a landscape plan.
Photo courtesy of Indiana Limestone Company

One benefit that has made limestone a choice product is the consistency of deposit. While subtle color and grain differences are present, limestone is extremely homogenous for a natural product. This is important, not only for the current project being built, but particularly when future expansions are contemplated.

When specifying building stone for structures that are expected to endure for generations, limestone is a great choice. Many colleges and universities across the country boast limestone buildings that are more than 100 years old. They continue using this venerable material in new construction, allowing them to match existing buildings and to maintain the context of their campuses.

Supply and Demand
In addition to its beauty and versatility, limestone remains an affordable building product because of the vast amounts available in the United States, particularly the northeastern region and states such as Indiana, Minnesota, Kansas and Wisconsin, says Ranier Devido, who started Ranier Devido Stone Company in New Castle, Pa., 52 years ago.

	Due to its plentiful supply, architects and builders often choose limestone for simple residential projects or ornate commercial jobs such as Washington's National Cathedral. Photo courtesy of Indiana Limestone Company

Devido says the supply in the United States is plentiful as long as new roads or other government actions don't block access to potential new quarries. "We need to live on our natural resources," Devido says, citing concern about a threat 10 to 15 years ago in which the government was considering taking quarry property to construct a new highway. And while there is no shortage of limestone in the United States, the natural stone often is imported from Europe, Mexico and Canada, giving buyers an even wider array of colors and densities from which to choose, Devido adds.

Duffie Elkins, of Indiana Limestone Company in Bedford, Ind., quarries more than one million cubic feet of limestone each year. The company exports raw material to countries such as England, Italy, China and Japan. Operating one of the largest limestone quarries in the country, and fabricating what they excavate, Elkins says in spite of increased demand, he isn't concerned about limestone reserves in the state.

"Everybody in the construction industry would be a [potential] customer of ours. I think overall sales of limestone are up. The industry has broadened our product line and appeal," through an increase in demand for the types of products crafted from limestone, he shares. "But we have probably 50 to 100 proven reserves. We've done core drilling and investigated where we might go."

Across the construction industry, the most significant development to come down the line in the past 10 years is the move toward green, sustainable building. The Leadership in Energy and Environmental Design (LEED) Green Building Rating System (from the U.S. Green Building Council [USGBC]) has defined standards for building environmentally responsible structures. Using regional stone (regional stone is extracted, processed and fabricated within a 500 mile radius of the job site) or using salvaged or reclaimed stone in construction of a new commercial building are the two most common ways natural stone, such as limestone, contributes to LEED standards.

Ranier Devido Stone Company in Pennsylvania fabricates Indiana limestone products.
Photo courtesy of Jane Bennett, Champlain Stone Ltd.

The natural stone industry as a whole is aware of the need to have a reclamation plan, and most quarries are trying to be as environmentally friendly as possible, cognizant of the need to fill in holes and plant trees, Elkins says.

"It's tough for us to prove that taking the stone out of the ground is environmentally sound," he admits, noting many in the industry who also are ahead of the pack when it comes to environmental awareness and proactive efforts. "But we try to reclaim twice what we quarry in a year."

While quarrying for limestone is not as destructive to the land as quarrying for aggregates, Indiana Limestone chooses to fill in with stone and dirt the 40- to 50-foot holes on the two to four acres they quarry each year, even though that effort is not required. Once the site is filled, the company plants and then "lets nature do the rest." The company occasionally chooses to create a lake from a quarried site to serve as a recreational spot for employees, Elkins adds.

Indiana limestone is recognizable by its creamy buff color.
Photo courtesy of Indiana Limestone Company

A source for limestone also exists in Canada, namely Owen Sound Ledgerock in Ontario. Operating on the Niagara Peninsula for 50 years, the company quarries dolomite limestone, high in magnesium and dolomite, which makes it a very dense natural stone, says Steve McCallum. Like his U.S. peers, McCallum says supply is sound for 75 years and beyond at many of his company's quarries.

"We're limited and tightly monitored by the government here in Canada," he says. "We have extractions of about 60,000 tons per year, so we're fortunate that we have unique stone so we can niche market competitively." McCallum says the unique dolomite limestone is in the mid-high price range. The company has exported the material for projects in Dubai, Italy and the Canadian Embassy in Berlin among other projects in Canada and the states, including the University of Michigan, Middlebury College in Vermont, custom architectural details for Yale University, large residential projects in Connecticut and the St. Regis Hotel lobby in San Francisco, Calif.

	Limestone Densities Dimension limestone is divided into three sub-classifications that describe their densities in approximate ranges, as follows: LOW DENSITY — Limestone having a density ranging from 110 to 135 lb/ft3 (1,760 through 2,160 kg/m3). MEDIUM DENSITY — Limestone having a density ranging from 135 to 160 lb/ft3 (2,160 through 2,560 kg/m3). HIGH DENSITY — Limestone having a density greater than 160 lb/ft3 (2,560 kg/m3). Source: www.natural-stone.com

Though they've not joined as USGBC members, Owen Sound does frequently supply LEED projects. "The exciting thing about this whole industry is that, even on a local scene, we might have once been seen as the scourge of the earth. People don't get warm and fuzzy about extracting stone. ... However, within the past 10 years, because of the green building and key words coming out like sustainable building, the perception of our industry has changed."

McCallum says more awareness by the general public of the non-invasive process of de-bedding stone, coupled with the knowledge that buildings constructed with natural stone can withstand centuries, thus reducing the cost and energy consumption of rebuilds, has contributed to a more positive attitude toward the industry.

Best Uses
Elkins says much of the limestone he sells is landscape products, as well as veneer products for residential use. Other mainstream uses for limestone are countertops, tile, fountains, pools, walls, walkways and fireplaces. Of late, people tend to want as thin a limestone veneer panel as they can get, either because of weight limitations on the building project or when under a time constraint that won't allow for a masonry set project, he says, but overall, today's use of limestone for building is consistent with its uses in the past.

"Indiana Limestone is a class two medium density stone, which means it has a creamy buff color," Elkins says. "People choose it because it's a complementary color that goes well with a lot of other exterior facades."

Easily fabricated, limestone will last for years.
Photo courtesy of Indiana Limestone Company

As a building product, limestone is a good choice because it's easily fabricated and though it's soft, it lasts for years. One downside is the way the stone reacts to acid rain and acid environment, adds Vinci.

"The only disadvantage that I see is that salt deteriorates the stone; it's one of the main enemies of limestone," Devido says, noting the practice in colder climates of salting roads and sidewalks to melt ice. "When limestone is used properly, it's a very good building material."

Structurally sound, limestone is a solid choice for new construction.
Photo courtesy of Indiana Limestone Company

A unique characteristic of certain limestone is the fossils and seashells often found embedded in the surface, adding an organic element. Some limestone is very porous, offering a more rustic or aged appearance, but also a better chance for staining and scratching if used for countertops. An acrylic-based sealer is recommended to protect the stone, which adds sheen to its appearance.

"There are definitely some instances in which limestone shouldn't be the first choice," Elkins says. "Like on the base of a building that will see a lot of splash or be in contact with dirt. You might want to use granite or [a stone] more impenetrable than limestone."

The Empire State Building is one of the most widely recognized examples of a limestone structure. Photo courtesy of Indiana Limestone Company

Throughout the industry, limestone is used today as it has been for centuries, for exteriors, architectural accents and fireplaces. But Devido sees one method changing. "They used to make [limestone] walls very thick; now they're thinning it down because they have better insulation and you can do that," he says. "And it works fine because limestone was always structurally strong."

Devido adds that the fire safety aspect of using limestone as a building material also has been recognized. Following big fires in Chicago (1871) and Boston (1872), the government mandated that all newly constructed governmental buildings be built using limestone.

"You'll find post offices in almost every state are made out of limestone," Devido adds.

At the end of the day, limestone offers a reasonably priced, flexible and esthetically appealing option for commercial and residential construction.

"The flexibility of limestone is the biggest element of its widespread use," Elkins says.

Karen Snyder is a freelance writer.

Resources
Duffie Elkins
Indiana Limestone Company Inc.
812-275-3341
delkins@indianalimestonecompany.com
www.indianalimestonecompany.com

Jim Owens
Indiana Limestone Institute
800-210-4863
ili@genuinestone.com
www.iliai.com

Steve McCallum
Owen Sound Ledgerock
519-376-0366
steve@ledgerrock.com
www.ledgerrock.com

Ranier Devido
Ranier Devido Stone Company
724-658-8518
rdevidostone@aol.com
www.devidostone.com

Joe Vinci
Vinci Stone
410-442-1460
stoneman@vincistone.com
www.vincistone.com

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