For this floor a 3/8" polymer modified overlay was installed over a wood subfloor and stained to resemble the look of marble.

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.

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.