Concrete Bathrooms The importance of design

The bathroom is an intimate room, not a place for cold, hard edges. So why is concrete increasingly used in bathrooms? “Concrete can be sculpted and shaped to work ergonomically with the human body, which is important for a bathroom space. And concrete doesn't rot: it's durable, it's water resistant, and it holds up to mold,” says Fu-Tung Cheng, principal, Cheng Design, Berkeley, Calif. Combine concrete's beautiful forms with comfortable utility and concrete becomes an obvious material of choice.

Amplifying the natural attributes of concrete, Cheng's Natoma bath included a sculptural countertop with two integral sinks spanning 12 feet. The polished color-free concrete floor included troweled-in beach glass, turquoise, and mother-of pearl.

Photo: Matthew Millman Photography

Chris Becker is big on design. Becker, president of Becker Architectural Concrete, South St. Paul, Minn., collaborates with homeowners and designers, who come to him with their own design ideas, to determine the best way to build. Becker uses Auto-Cad and “Sketch Up,” software to create renderings that give the client multiple views. “They try on the installation to see how the design will fit,” says Becker. “The challenge is to thoroughly interview the client to determine what they are looking for.” He offers clients four different countertop choices using the branded name Creo Cast Concrete:

Mike McDaniel, an interior designer with Robb and Stuckey, Scottsdale, Ariz., combined Asian and Western influences to contrast raw timber and natural stone with stained and cast concrete. The main countertop was made with the Cheng mix finished in place, right side up, instead of the usual reverse-cast method. This permitted a burnished trowel finish to create the aged appearance the owner desired. The installation was epoxy sealed to protect against water and the unique Kohler Purist sinks and faucets completed the work.

Becker's center-island porcelain dual-sink bath won the Cheng Design Challenge for the Best Bath Countertop in 2007. “Self-consolidating concrete (SCC) is less pervious to water. It's more dense, casts easily, and when the ‘spread' is greater, casting can be bughole free. It's an excellent mix to use for countertops and integral sinks,” says Becker, who uses this as the base for his reverse-cast mix. An added bonus for Becker is the breadth of colors he can offer designers, which he says drives his countertop business. Becker finishes his self-consolidating-concrete countertops by diamond polishing at 100-, 800-, and 3000-grit levels and then applying polishing impregnators and wax.

For the Natoma project, a remodeling project in San Francisco, Cheng incorporated wood, concrete, and tile into an earthy color palette to create a gentle atmosphere. Cheng combined a curved ceiling architecture with a square bath plus integral double cylinder-shaped concrete sinks cast into a rectangular 12-foot-long countertop. The 2-inch-thick countertop was cast-in-place with Cheng's Pro-Formula mix; its two sinks include integral color and fiber reinforcement. Decorative fossils inserted into the form before casting are revealed when demolded. On previous projects, Cheng has buried shells, children's toys, and metal objects in showers and countertops—another way to soften the atmosphere and reflect a client's essence. The integral sinks and countertop are designed to receive a concrete insert that keys into the sink sections. The insert masks a center drain creating the illusion of one continuous large sink. The glassy finish characteristic of Cheng's work is finished with a sealer, then waxed and buffed. An I-beam that holds the three-section countertop together, and runs under the front edge of the counter, is part of the wall-mount system.

Most any decorative concrete floor can be used for bathrooms: stained and colored overlays, stencil applications, polished, or stamped. Interestingly, contractors report that homeowners are more concerned about a slippery floor than water and urine stains. Perhaps there is an assumption that the product is capable of withstanding stains so contractors and designers need to provide a dense, less stain-prone, and well-sealed nonslippery floor. For instance, Cheng's Natoma project included a polished floor with troweled in beach glass, turquoise, and mother-of-pearl. It was ground and diamond polished, then sealed with a penetrating sealer. The dense polished surface still reflects the beauty, but the shine is softened and the slipperiness reduced.

Becker's award-winning bath was a remodel with an uneven concrete floor that needed a ¾-inch elevation change. The design took advantage of the distressed floor and included a bed of natural stone that meandered through the floor and up the shower wall in a recessed pathway. Becker used self-leveling overlay material to even and lift the floor allowing for the recessed area, and followed with a troweled-on microtopping that was chemically stained with two concentrations of a dark tobacco color. The floor was sawcut into large squares and later grouted and sealed with a water-based epoxy. Six coats of water-based floor wax completed the floor.