Types of Concrete Overlays
A stamped overlay offers all the aesthetic benefits of conventional stamped concrete but is less time- and labor-intensive to install. The overlay mix is usually applied by a gauge rake (a tool with an adjustable depth gauge for achieving a uniform topping thickness) and then imprinted with stamping mats or texturizing skins. These semi-flexible stamping tools are available in dozens of patterns, allowing overlay installers to duplicate the beauty and texture of natural stone, brick, slate, wood planking, and other materials. Overlay thicknesses range from 1/4 to 3/4 inch, depending on the depth of the imprint.
Microtoppings and Skim Coats
These ultra-thin decorative toppings are applied by a trowel or squeegee in layers as thin as 20 mils, or a mere 0.02 inch. They can go on silky smooth and taken down to a featheredge. Or you can apply several coats to create a textured broomed or troweled finish. Some systems come pretinted in a wide range of colors while others can be custom tinted by mixing in the desired amount of liquid coloring agent. Interesting color variations can be achieved by applying layers of different hues.
These versatile systems offer a wide array of finish options. Usually they are sprayed evenly onto concrete with an air-powered hopper gun, but they can also be applied as a splatter coat to created a textured, slip-resistant surface or "knocked down" with a trowel to create a smoother finish. A popular decorative technique is to use paper or stencils to produce designs ranging from decorative borders and medallions to tile patterns to embossed or inlaid motifs.
These flowable polymer-modified toppings have the ability to self level without troweling, making them ideal for smoothing and leveling worn or uneven concrete surfaces. Installers simply pour or pump the material onto the surface and then use a spreader to distribute it evenly. The overlay can be left seamless (except at control joints) or used as a canvas for sawcut or engraved designs. Or you can incorporate decorative inlays, such as strips of wood or metal, by adhering them to the base concrete and then pouring the overlay to the level of the inlay. Self-leveling overlays can also be enhanced by staining or dying. In some applications, they serve a purely utilitarian purpose as an underlayment for tile, carpet, or other floor coverings.
Epoxy Terrazzo Toppings
This mosaic-like floor topping is known as thin-set epoxy terrazzo, a poured-in-place topping for concrete substrates that goes on at a thickness of only 1/4 to 3/8 inch. It is excellent for multi-colored patterns and designs because of the epoxy resin matrix. It can be pigmented, like paint, to achieve an unlimited spectrum of colors. It can also be colored with aggregates, including chips of marble or granite, recycled glass, mother of pearl, and various synthetic materials.