Long before resilient flooring or carpet, natural stone flooring was the surface of choice — for a lot of obvious reasons. This natural flooring is making a comeback — this time as a design statement.

“Sales are up,” says Frederick Hueston, director of the National Training Center for Stone and Masonry Trades, Asheville, N.C. “Stone flooring has probably grown 100 percent in the past couple of years.”

Stone and “stone”
There are two basic types of stone floors — natural and man-made. Natural stone includes marble, granite, slate, limestone and sandstone. Porcelain, ceramic, poured concrete and terrazzo are examples of man-made “stone.”

Perhaps the most popular natural stone for flooring is granite. It is the hardest and most durable. Limestone is also growing in popularity for commercial applications.

“The possibilities are endless,” says Steve Williams, vice president of Williams Tile, St. Louis, Mo. “Staying ahead of that game is impossible for me. [People] are always finding new variations of the stones at different quarries.”

Stone should not be installed where it could be easily scratched, like in an office with moving furniture. Similarly, less-attractive concrete might not be the best choice for a highly visible hotel lobby. Stone floors are not popular among such high-traffic areas as schools, warehouses, and department stores. But stone floors are popular design elements in hotels, banks, office buildings, and homes.

“Flooring takes both image and functionality in mind,” says Dave Barela, West Region training manager and certified hard-surface flooring inspector for Magee Industries, a division of JohnsonDiversey, Racine, Wis. “A prestigious hotel may select polished granite and marble because they produce an excellent visual appeal and luxurious look. While a fast-food restaurant may select quarry tile because it is low maintenance, durable, and easier to clean.”

Stone floors often cost more — sometimes substantially more — than conventional flooring. A premium is paid up front, but floor-care experts say the costs are offset by lower maintenance costs.

Stone-cleaning words to the wise
Stone is among the most challenging type of floors to maintain — in part because it is an unfamiliar surface for many cleaning crews. The first consideration in developing a stone floor-care plan should be to obtain maintenance guidelines from manufacturers and distributors. Most floor-covering manufacturers offer care instructions on their Web sites. Incorporate these guidelines into written floor-care procedures and into employee training.

Reduce cleaning by using mats or area rugs, especially inside and outside of entranceways. This will help minimize sand, dirt, and grit that can scratch the floor. Be sure the underside of the mat or rug is a non-slip surface. It is also wise to use mats under planters, desks, or other objects that might scratch the floors.

“The most important thing anyone can do to a stone floor is to keep the dust and grit off of it,” says Hueston. “If you don’t have grit, it won’t scratch.”

Routine cleaning of stone floors, however, is well within the learning curve of an in-house cleaning crew. There are some guidelines to remember, however, to prevent costly mistakes:

  • Dust-mop the floors frequently (at least two or three times a day in high-traffic areas) using a clean, non-treated rayon mop. Also, wet mop with a mop and bucket or a walk-behind scrubber once a day. Be sure to change rinse water frequently.

    “Using dirty water will trash a floor,” says Williams.
  • Be careful when using chemicals. Choose a neutral cleaner designed for stone or a stone soap (other cleaners can leave a film on the surface). Scouring powders and acid cleaners, including those with citrus, will do more harm than good to a stone floor.

    “I’ve seen nightmares where someone used a pink-colored sweeping compound and they ended up with big red stains,” says Hueston.
  • Cleaning crews often worry about grout, which is porous and likely to soak up dirt and grime.

    “Grout is notoriously difficult for most maintenance workers to keep in like-new condition,” says James Peduto, president of Matrix Integrated Facility Management, Johnson City, N.Y.

With properly installed stone floors, however, grout should not be a cleaning nightmare. Certain stone floors, including designer concrete and terrazzo, can be installed without grout lines. With proper sealing, grout in other types of stone floors should not be an issue.

The only potential problem comes with sanded grout. The sand can come loose from the grout and then scratch the floors. Before beginning a cleaning program, have a stone-floor professional evaluate the floors and, if you have sanded grout, ask about appropriate sealers or seek professional help with cleaning.

Stone sealers a must
Thanks to their porosity, stone floors need a sealer, which allows them to breathe and protects them from spills. This is important for both natural and manmade stones.

Crews should apply a small amount of a silicone-based impregnator to the surface, including grout, and let it set for 10 minutes. If it soaks in too quickly, apply more. Remove remaining impregnator left after 10 minutes with a clean cloth and buff the floor with a white buffing pad. Impregnators and sealers should be applied only after the floor is thoroughly cleaned, rinsed and dry.

“Sealers are a really good idea,” says Williams. “It’s not a 100 percent guarantee, but they work really well. We recommend [sealers] for all stone floors.”

It may be worth the cost to invest in professional floor sealing. In recent years, there has been an influx of stone-care chemicals and product lines that appear to be so user friendly that anyone can restore his or her own stone surfaces. That’s not the case. Inadequate or incorrect cleaners and sealers for stone have become so common that stone professionals often say the majority of their business is dedicated to correcting the problems caused by these cleaners and sealers.

One area that is most certainly best left to the experts is restorative work, including sanding and re-polishing.

When a shiny stone floor starts losing its gloss it can be polished using a standard 175-rpm, weighted (145 pounds) floor machine using a hog’s-hair pad, and either an acidic or non-acidic polishing powder. The powder is applied to the floor in a small section, worked into a slurry, and the process continues until the desired look is achieved. Sounds easy, but getting it wrong can be costly.

“A lot of people screw up stone because they don’t know what they are doing,” says Dave Frank, an industry consultant. “Once you screw it up it’s tough to get it back to what it used to be.”

High-traffic areas may need to be re-polished once a week. Other areas can be polished a few times a year.

It is also possible to repair scratched, rutted, or otherwise-damaged stone. This work is also best left to specialists who have the equipment and experience.

“It’s difficult to ruin a stone floor. There’s little you can do to destroy it short of taking a jackhammer to it,” says Hueston. “Mistakes can always be repaired but it may require the services of an expensive restoration crew.”

Becky Mollenkamp is a free-lance writer based in Des Moines, Iowa.