Using Decorative Concrete Indoors
By: DEBRA WILLIAMS
Impressed by the marble flooring in a neighbor's house? Intrigued by the aged brick flooring in a newly constructed home? What about your in-law's kitchen tile that never stains or chips despite the abuse of five children?
Well, all of these homes could share a common secret: the use of architectural, or decorative, concrete as indoor flooring. The popular choice for inexpensive, durable and attractive walkways and patios is now appearing in more kitchens and dens.
"I rarely pick up a home decorating magazine without finding a picture of a colored cementitious floor or a stained concrete slab used as a design element. People are becoming more aware of the design flexibility, economic benefits and low maintenance provided by using concrete flooring indoors," says Rod Pedzinski, Western Division Manager for L.M. Scofield Co. Pedzinski was closely involved in the development of Scofield Overlay, a self-leveling colored cementitious topping that can be chemically stained.
The trend can be traced back to the recession of the early 90s when builders of upper-end homes found themselves facing excessive cost overruns.
"Instead of finishing with slate or marble, builders turned to concrete staining," explains Barbara Sargent, owner of Kemiko Concrete Products. When she first started in the business 29 years ago, Sargant says architectural concrete was almost exclusively used in commercial establishments like restaurants and shopping centers.
While its cost effectiveness continues to draw homeowners and contractors, a growing number are attracted by its low maintenance and artistic quality.
"When a family is home, they don't want to be bothered with the floor. If a child spills kool-aid on concrete, it's not a big deal," Sargent adds.
Pedzinski adds that decorative concrete can be used to achieve a contemporary look, an aged natural appearance, or something unique.
"Many homebuilders turn to decorative concrete as an inexpensive alternative to mimic the look of natural stone, like marble, granite or cobblestone. Not only is natural stone itself expensive, it's costly to ship, costly to install and has a negative ecological impact. Add to that the difficulties of matching a particular color to other materials and there's an increased potential for construction delays," he explains.
Using decorative brick indoors gives homebuilders and owners new options, ones that were previously unavailable because of cost or geography.
"Basically, whatever you see outdoors, you can recreate indoors," says Monica Stamper, owner of Concrete Packaging Inc., the Orlando-based manufacturer of Kover Krete.
Mark Donaldson, owner of Skookum Floor Concept Ltd., says one of the main advantages in working with decorative concrete is the ability to create curved lines, lending the authenticity of natural stone or adding geographic interest to a contemporary home.
"When you install a concrete floor, you can cut it into large slabs. You are not limited to 1' x 1' squares. Generally, you don't have that option with tile. Now that they have the option, homeowners often want to do something different."
Decorative concrete indoors can take a variety of forms, but usually stems from either staining the original concrete or applying an overlay.
Kemiko's stained products are a rarity in the industry: a product marketed to both contractors and do-it-yourselfers. Sargent estimates that homeowners apply 65-70 percent of Kemiko products sold.
"If the funds are available get a professional," she says. She adds that do-it-yourselfers with a lot of projects under their belt shouldn't be intimidated. "If you're someone on a limited budget with a smaller home, there's no reason you cannot successfully apply the stain."
The staining process begins by covering all walls with paper to prevent any stain splatter. Always begin with a small test preferably in an easily hidden area.
"No two floors are alike," Sargent says. "You can look at a color card and say that's the color I want, but it may not work on your floor. Test an area and make sure it's what you want before you do the entire floor."
For staining, surface preparation will depend on the condition of your floor and the product you will be using.
A brand new floor with a smooth surface may require little prep. But if you have an older home and you don't know what has been used on the floor, you'll need to check with the manufacturer of the stain you're planning to use for cleaning advice. Most will recommend specific cleaners for stains like rust or ink. Many manufacturers also make special treatments for use in surface prep.
Sargent recommends spraying Kemiko Stain using a plastic garden sprayer similar to those used for spraying insect repellents. Let the stain dry completely, then spray a second coat and let it dry overnight. When the stain is completely dry, remove any residue. Sargent says that this may require cleaning the floor several times. Once the floor is clean and dry, use a sealant or a wax. (Wax is only used on indoor flooring.)
Sargent emphasizes that the most important step in using stain is to read and follow the manufacturer's instructions to the letter.
For overlays, the process is much different. Overlays function as a completely new covering to existing concrete and are almost always applied by contractors. For overlays, the stain is mixed in the concrete mixer to give an even color.
For the process to work on concrete in remodeling projects, the concrete must be stable and structurally sound. If it's cracked, sections can be replaced although that's not always the most cost efficient route.
"Most problems can be fixed," says Craig Reed, Technical Services Manager at Bomanite, an architectural concrete manufacturer headquartered in Madera, Calif. "If the concrete has a lot of cracks, it may be just as inexpensive to put down new concrete."
For new home construction, Donaldson says crews usually choose not to work directly on the structural slab.
"Usually, at that point, you're looking at a few more months of construction and it could end up getting damaged. We like to come in during the finishing work, when most of the construction is done. A quick resurfacing treatment gives us a brand new floor to work with."
Donaldson says decorative concrete overlays are as strong and as durable as the original concrete slab with averages of about 7000 psi.
Decorative concrete overlays aren't just limited to use on concrete, though. That's a common misconception among designers and some homebuilders. New product innovations have made it appropriate for use on almost any base.
"It can be put over wood. It can be put over metal or linoleum tile," says Matt Casto, Bomanite's Vice-President and Director of Technical Services. Weight is not an issue, either. Decorative concrete can be used on second story floors just as it can in basements.
Donaldson, who recently installed decorative concrete at the Vancouver International Airport, always uses rollers or sprayers to apply a sealant to decorative concrete.
"Without it, it's just like having unfinished wood on the floor. If you spill anything, it soaks in and the stain will never come up. A sealant prevents that absorption and protects the color."
Designs or the appearance of natural stones are then stamped or cut into the overlay. Stamper says that a stamped tile appearance in a decorative concrete overlay costs $7-9 per square foot. In comparison, tile will cost $12-15 per square foot.
While most of his flooring jobs are uneventful, Donaldson does have some tips to pass along when working with radiant heating installed in the flooring. He advises that the heat not be used for 30 days after the concrete has been laid. Otherwise, the pipes can actually heat through the floor, leaving impressions of their lines. Applicators also need to make sure that the piping allows the depth needed to cut decorative lines.
Using architectural concrete indoors has one distinct advantage over its use outdoors. The elements — rain and cold temperatures — that can delay the application of decorative concrete outdoors are irrelevant indoors.
The only drawback to the use of decorative concrete overlays stems from one of its biggest attractions: permanence. Decorative concrete maintains its original color for decades with little maintenance. Generally, damp mopping and waxing as needed is all that's required.
This longevity can sometimes create a problem when homeowners want to change the flooring.
"You can remove an overlay, but it's not an easy thing to do," Donaldson says. "Generally, when you put a topping on, it's designed to bond. They're difficult to take out."
Stamper adds that the process can also be expensive.
Overlays are usually one-fourth of an inch thick, so a layer of carpeting or other floor covering can usually be added without too much concern for height. Staining adds no height to the flooring, so no option is ruled out for homes with stained concrete flooring.
"You can cover it with anything you want," Sargent says.