When you think concrete countertops do you image a piece of sidewalk resting on top of the cabinets in your kitchen? If you do, you wouldn’t be the first person. In reality, concrete for your countertops is a highly design-oriented and skilled trade with each top being completely unique from the next. The following article will outline some basic information on fabricating concrete for those fabricators deciding whether or not to add concrete to their offerings.
Why Concrete? Each new countertop material offers new possibilities to the designer and the consumer, giving the fabricator a broader palette to offer with ensuing profit opportunity. Concrete for countertops produces beautiful, honed surfaces that are wonderful to touch and complement other natural materials. With basic care, concrete countertops grow in beauty throughout the years. One of the advantages of concrete is that it is infinitely formable in an infinite number of colors; therefore, the only limitation in design is the imagination of the designer.
Business matters. Each concrete countertop is a custom job and can be profitable. Building tops for a typical kitchen takes a few hours a day over a five day period. Material costs are low, and with typical prices for a finished concrete countertop start around $75 per sq. ft. for a basic slab, there’s a nice profit margin to be enjoyed. While some approaches to fabrication can require more specialized tools, such as vibrating tables and other devices, expensive tools are not required.
Templating and moldmaking. While concrete tops can be poured in place, an experienced fabricator will generally bring the template back to the shop. Molds, as one-offs, are mostly made by hand, although some fabricators have begun digitizing templates and cutting molds out of Styrofoam on CNC machines. This may not work for complex molds such as molds involving integral returns or backsplashes, drainboards, built in trivets, custom edges, an integral concrete sink or a very creative shape. The mold must have openings or allowances for sinks, ranges, faucets, drains or overflows. Mold making is key to the fabrication process and it must be completely accurate. While some minor adjustments can be done at installation, concrete is HARD and it’s much easier to make it right to begin with!
Casting. Once the mold is built against a non-porous surface such as melamine, there are three basic techniques for casting: hand-packing, wet casting (with or without vibration) and spray. Casting can be done upside down or right side up, depending on the desired look for the top. Concrete countertop fabricators can make their own concrete mix or use a specialized bagged mix. Hand-packing mixes can produce natural looking veined, ground or troweled surfaces while wet casting or vibrating mixes can yield a fine, even surface. Spray application of a face coat, coupled with GFRC reinforcement techniques, produces an extremely smooth, machined looking surface that often doesn’t need polishing. One can add additional aggregate, such as rocks, glass, seashells or nearly anything to the concrete to make it ‘greener’ or for design reasons. You can inlay almost anything into tops during casting or cast in gaps to insert items later, like a favorite tile or a metal trivet.