A concrete overlay covers up surface imperfections in your existing concrete floors. With a variety of decorative options, almost any concrete slab can be given a complete face-lift at a lower cost than removal and replacement.
See how you can add dazzle to your floors with a metallic coating.
Before you read any further, it's important to know that not all existing concrete floors can be resurfaced. The underlying base for an overlay must be sound. If your concrete has severe cracks or other damage, resurfacing will not solve your problems and pouring new concrete will be your best option. (See Is it worth fixing?)
Now, the real challenge is choosing from the many overlay types and the diverse array of decorative finishes possible. There are multiple options available for achieving any look imaginable with a concrete overlay.
CONCRETE FLOOR OVERLAY TYPES
Here's a primer of the various overlay types available and the decorative options with each. We also give you pointers on how to choose the best system for a particular application. With the many options available, you're sure to find at least one system that meets your requirements for durability, appearance, maintenance, and cost.
Although cement overlays have been around for decades, many of today's systems blend polymer resins with cement, sand, and other additives to improve performance, wear resistance, and aesthetic qualities. Polymer-modified overlays can be applied in layers as thin as a credit card or up to several inches thick without delamination or failure. They adhere well to existing concrete and resist damage from salt, chemicals, UV exposure, freeze-thaw conditions, and abrasion.
While most types of polymer-modified overlays offer similar performance benefits, each system has its own unique characteristics. Overlay manufacturers use different types of polymer resins, often blending them to produce proprietary products with distinct physical attributes. Many of today's decorative overlays use acrylics or acrylic blends because these resins provide excellent bond strength and UV resistance.
Consider these factors when selecting your overlay system:
What is the state of the existing floor?
Does the concrete have a lot of cracks or pitting? Is the surface out of level? If so, choose a higher-build material, such as an underlayment or self-leveling overlay, that can be applied at a thickness of 1/4 inch or greater.
Too much moisture in the concrete substrate can also be a problem for some overlay systems, especially products that restrict the ability of the concrete to breathe or release moisture vapor as needed. There are simple tests you can perform to check the moisture vapor emission rate of concrete. If it's too high, be sure to use a permeable overlay system that will permit the moisture vapor to escape. (Read more about reducing bond failures caused by moisture vapor transmission.)
What conditions will the overlay be exposed to?
Be sure the overlay system is tough enough to withstand all the conditions it will confront. Is it a floor surface in a high-traffic area or subject to chemical, grease and oil spills? Some systems are better suited than others for harsher exposure conditions. Ask the overlay manufacturer or installer to confirm that the material you plan to use will work for your purposes.
What look do you want to achieve?
Of course, the main reason to use a concrete overlay is to restore and beautify existing concrete. Determine the color, pattern and texture you want for your rejuvenated surface and then find a system that can achieve the look you desire. Consult with the overlay manufacturer and your installer for advice. Ask to see samples of various finishes and color selections as well as a portfolio of completed projects.
How easy is the product to mix and apply?
Ease of use may also influence overlay selection, especially if you're the installer. Some products come preblended like a cake mix, and all you need to add is water. Others require mixing the polymer additive and any pigmentation desired with the cement and other dry ingredients. Some overlays can go right over properly prepared surfaces; others require application of a primer or bonding agent before overlay placement. Pourable, self-leveling systems tend to cover floors faster with less finish work than trowel- or spray-applied products.
How much maintenance is required?
Most decorative overlays, when coated with a protective sealer, are very resistant to stains, dirt and grease. Still, they will need occasional cleaning to look their best. Floor overlays typically require routine sweeping to remove any abrasive particles and occasional wet mopping with a mild detergent, depending on how much traffic they receive. Ask to have all cleaning and maintenance procedures and life-time performance expectations put down in writing before committing to a particular care regimen.
CONCRETE OVERLAY BEFORE AND AFTER PICTURES
Envision Concrete in Escondido, Calif. (Before)
Concrete Canvas in San Marcos, TX (After)
Envision Concrete in Escondido, Calif. (Before)
Envision Concrete in Escondido, Calif. (After)
COMMON QUESTIONS ABOUT CONCRETE OVERLAYS
Is your existing concrete floor, sidewalk or driveway a good candidate for a decorative concrete overlay? To help you decide, here are answers to eight common questions about overlay application, appearance, performance, and maintenance.
Can a decorative overlay be applied to all existing concrete surfaces?
Not always. It depends on the condition of the existing concrete. The underlying base for an overlay must be sound. If your concrete is heaving, has severe cracks, is spalling due to damage from deicing salts and freeze-thaw cycles, or resting on unstable soil, an overlay will not fix your problems. If your concrete is simply discolored or has minor stains and cracks, then an overlay is an ideal way to cover up these surface imperfections and give your concrete a complete face lift. For more information, see When to Use a Polymer Overlay.
Are different finishes and textures possible with a concrete overlay?
There really is no limit to the finishes you can achieve with a decorative overlay, ranging from ultra-smooth to heavily textured. It all depends on the type of overlay system and the tools used to apply it. A knock-down texture is probably the most popular finish for spray-applied toppings. With microtoppings and skim coats, you can achieve a wide variety of decorative finishes by using tools such as hand trowels, floats, rollers, and rubber squeegees.
I love the look of stamped concrete. Can an overlay also be stamped and colored?
Absolutely! With stampable overlays, which are typically applied at a thickness of up to 3/4 inch, you can use the same stamping mats and texturing skins used for traditional stamped concrete to produce patterns and textures that mimic stone, brick, slate, and other materials. Texturing skins produce a seamless texture with no grout lines while mats produce a deeper pattern with well-defined lines. You can also add color using the same dry-shake color hardeners and antiquing releases used for typical stamped concrete.
How durable and long-lasting is a concrete overlay? Will it wear well under heavy traffic?
When an overlay is applied properly and well-protected by a sealer or coating, it should last indefinitely, even under heavy foot or vehicle traffic. On floors, the use of a floor wax or polish can provide extra protection in high-traffic areas. The key is to reapply the sealer or wax if it begins to show some wear. Otherwise, wear patterns may begin to show, especially in colored surfaces. For more information, see Concrete Overlay Maintenance.
For this floor a 3/8" polymer modified overlay was installed over a wood subfloor and stained to resemble the look of marble.
Can I apply a cement-based overlay over wood or tile surfaces
Many cement-based overlays can be placed over vinyl flooring, tile or wood if the surface is prepared properly. In fact, some overlay products are formulated specifically for this purpose. For more information, see Making the Switch to Concrete Floors.
Can an overlay be polished, like standard concrete?
Yes. Many overlay systems can be polished to a smooth, high-gloss finish. These systems are especially popular for people who want polished concrete but need to hide imperfections in an existing slab. Learn more: When to Use a Polishable Overlay.
Can an overlay crack or delaminate?
It can if it’s installed over an unsound surface. Because overlay materials are polymer modified, they are designed to go down thin and still remain strong and wear-resistant. But overlays are only as good as the subbase they are applied to. They are not intended to fix bad concrete. If you put an overlay directly over a cracked surface, the overlay is likely to crack as well. Delamination is caused by excessive moisture rising up through the subbase, a good contractor will test for excessive moisture vapor transmission and apply some type of a membrane between the existing surface and overlay if necessary.
How long does it take to install a concrete overlay?
One of the big benefits of a decorative overlay is that it can restore existing surfaces quickly with minimal downtime. Polymer overlays cure fast, and some systems can support foot traffic within a few hours. However, the total time for overlay installation will vary with each project depending on surface preparation requirements, the decorative treatments used, and curing conditions. Ask your overlay installer to explain what installation involves and the timeframe required to complete the job.
HOW TO INSTALL A CONCRETE FLOOR OVERLAY
A decorative concrete overlay or microtopping is a great solution for restoring and enhancing worn, damaged or discolored concrete floors. Overlays can also be placed over other flooring materials, such as vinyl tile or wood. The application tools and techniques for installing cement-based overlays will vary, depending on the type of system being applied, the size of the project, and the look you are trying to achieve. Always refer to the overlay manufacturer’s installation recommendations for their specific product.
The most critical step when installing any cement-based overlay system is surface preparation. You’ll need to clean the substrate, remove any existing coatings, and then profile, or roughen, the surface to ensure a good bond. There are several methods you can use to profile concrete, including acid etching, shotblasting, diamond grinding, scarifying, and sandblasting. For guidance, see Concrete Surface Preparation.
If there are cracks in the concrete, they also must be repaired before you can install the overlay so they won’t reform and mirror through to the topping. The type of repair method you use will depend on the nature of the cracks. See these concrete crack repair tips.
Watch These How-To Videos
Concrete Overlays over Vinyl or Linoleum
Time: 01:54 Video showing how you can install colorful and durable concrete floors over vinyl.
Installing a Concrete Floor Over a Wood Subfloor
Time: 01:10 Concrete floor video on how to install concrete over an existing wood subfloor.
Installing Concrete Floors over Tile
Time: 02:59 Get ideas for concrete floors and installation tips.
Concrete Floors Baseboards & Transitions
Time: 03:30 Concrete floor video on how to install baseboards
