Concrete Micro-Toppings
Thin Is In: Micro-toppings Offer Beauty and Versatility
by Denise Wendt
are as versatile as they are beautiful.
Defined by their thickness — or lack of it — they are generally between 1/32-inch and 1/8-inch thick. They are typically applied with a trowel or squeegee but can also be broom finished.
By contrast, self-levelers generally require at least 1/4-inch material and are poured into place. Micro-toppings do not have the flow characteristics or sufficient mass of material to flow and so are not considered self-leveling.
This paper-thin concrete mixture is easy to install and bonds to almost any properly prepared existing surface, including concrete, other overlays, wood, metal, plastic, terrazzo, ceramic tile, marble and asphalt. They should not be used over gypcrete, vinyl or rubber.
Micro-toppings can be used on interior and exterior surfaces, residential and office walls and floors, lobbies, retail walls and floors, decks, patios, ceilings, countertops, showers, masonry, bleachers, food concession areas, waterparks, sidewalks and driveways. “The more flexible the micro-topping is, the more versatile it is with regards to what substrates it can be used on top of,” says Lee Tizard of Floric Polytech in Rancho Cucamonga, Calif.
Ron Borum of Miracote in Rancho Dominguez, Calif., stresses that these various substrates do need to be in good condition before a micro-topping is applied. “Micro-toppings are not necessarily a solution to resurface distressed concrete,” says Borum.
Gary Anderson of Tri-Co Floors in San Diego, Calif., agrees. “Micro-toppings can do some flexing, but over time they will crack,” says Anderson. “So you need to start with a stable floor.”
Anderson estimates that micro-toppings can save up to 25 percent compared with using other types of overlayments. Tizard agrees. “Without sealers, micro-toppings can start as low as 45 cents per square foot of material,” he says. “Self-levelers start at $1.50 and go to $3.00 per square foot.” Borum adds that wax and maintenance should be figured into the final cost of the system.
Micro-toppings can be more cost-effective from a materials standpoint, but they’re not always more cost-effective from a labor standpoint, says Tizard. “That really depends on what the profile of the job is and how good the contractor is,” he says.
As with other architectural concrete products, you’re limited only by your imagination. “We do a lot of things with micro-toppings that other people don’t do,” says Anderson, who recently installed 23,000 square feet of micro-topping on the concession area floors at the Las Vegas Convention Center.
“Micro-toppings offer infinite design, texture and color possibilities,” says Borum. And sealer selection affords multipurpose uses, slip resistance, chemical resistance, easy maintenance and cleaning, a variety of gloss levels, and protection.
“When used in combination with repair mortars, you can take any existing space and resurface it to make it look like a brand new canvas,” says Tizard. “You can incorporate thin-gauge stainless steel inlays into the micro-topping using Mylar stencils to create patterns. You can overlay the micro-topping with metal and seal it with epoxy to give the effect of terrazzo strips. Sandblasting is often used to achieve the look of a stencil. Micro-toppings can be used on top of self-levelers to enhance features and details of self-levelers. You can achieve a more random look with a slop trowel application method.”
One of the advantages of micro-toppings over self-levelers has to do with water. “Because micro-toppings don’t require the amount of water that self-levelers do, there are fewer inherent shrinkage issues and subsequently fewer problems with shrinkage cracks,” explains Tizard.
Most micro-toppings also have a higher percentage of polymer solids than self-levelers, which adds flexibility to the product. “If you have a really cracked up slab, you can incorporate micro-toppings with fracture-resistant membranes to create a monolithic slab without the effects of cracking,” says Tizard.
Our experts generally agree that curling is not an issue with this product. As long as the products are well formulated, curling is not a problem, says Borum, who adds that “some micro-toppings are more ridged than others and can be problematic if the substrate moves, expands, contracts or otherwise deforms beyond the micro-topping’s ability to withstand the stress.”
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