Sealing Concrete Patios

Will a Sealer Make Concrete Patios Slippery?

Film-forming, high-gloss sealers can really intensify the color of a concrete patio, but they may also make the surface more slippery, especially when wet. That’s usually not a concern with exposed aggregate or textured concrete patio surfaces, but smooth, untextured concrete may require the use of anti-skid additives to improve the traction. Most of these additives are simply mixed into the sealer at the time of application and are transparent, so they won’t alter the color or appearance (see Making Concrete Slip Resistant). Another option is to switch to a penetrating sealer that won’t form a surface film.

Can a Patio Sealer Be Colored?

Most clear water- and solvent-based sealers can be tinted, allowing you to add another layer of color to a decorative concrete finish. Some manufacturers offer pre-tinted sealers, while others provide tint concentrates that you can add to the sealer at the jobsite. A tinted sealer can also be used as a stand-alone, low-cost decorative finish if just a hint of color is desired. Get more advice on tinting sealers.

How Do I Prepare the Surface?

The answer to this question often depends on whether you’re applying sealer to a new of existing concrete patio. In order for a sealer to properly adhere to the concrete, the surface must be free of dirt, oil stains, existing coatings, and any other substance that might inhibit sealer penetration. Newly placed concrete patios typically require very little preparation, while existing surfaces may need to be power washed with soap and water and possibly acid etched.

The porosity of the concrete is also important and will determine how well the sealer will soak into the surface. If the sealer can't adhere, it won't be long before it peels off and flakes away. Because most patios are hand troweled, they are usually porous enough to accept a low-solids sealer without additional surface profiling. However, if the concrete is very tight or dense, you may need to open up the surface by light sanding or acid etching. For more guidance, see Preparing Surfaces for Sealer Application.

When Should I Seal My Concrete Patio?

When you apply a patio sealer is almost as important as good surface preparation in terms of long-term durability and performance. The biggest factors to consider are the age of the concrete, weather conditions, and dry times.

New concrete patios should be allowed to cure completely before sealer application (typically at least 28 days). Most sealers also must be applied to dry surfaces. With stamped concrete, it’s especially important to make sure the patio is free of moisture in low spots of the stamp pattern, where water may accumulate.

You should monitor the air temperature as well. As a general rule, wait to apply outdoor sealers when the temperature is between 50 to 90 degrees F both during and for at least 24 hours after application so the sealer will cure properly (see The Effects of Temperature on Sealer Reactivity).

Also make plans to apply sealer when the patio won’t be in use for a few days. Depending on the product you’re using, dry times for concrete sealers can range from one to three days before the surface can be exposed to a lot of backyard foot traffic.

Is it Better to Roll or Spray Patio Sealer?

Many sealers for concrete patios can be applied using simple tools, such as a paint roller or pump-up sprayer. As a general guide, solvent-based sealers are best applied by spray while water-based sealers are best applied by roller. If the patio is textured or stamped, be sure to use a roller with a fairly thick nap so you can work it into the depressions. One of the best application techniques when sealing stamped or textured patios is to combine spraying followed by back rolling to keep the sealer from settling in low spots.

Whether you are rolling or spray applying a sealer, always follow the manufacturer’s recommended application guidelines and coverage rates. Often you’ll get better results by applying patio sealer in two thin coats, which will ensure more uniform coverage. If you apply the sealer too thickly, it will just lie or puddle on the surface rather than penetrate.

For more application tips see:
How to Apply Concrete Sealer
Choosing the Best Applicator for Concrete Sealer

When Is It Time to Reseal a Concrete Patio?

Even when properly applied to a clean well-profiled surface, a sealer will wear away over time. The average service life is three to five years, depending on foot traffic, weather, and other exposure conditions. Resealing a concrete patio on a regular basis will help to preserve its color and resilience.

There are several ways you can tell when a patio needs a new coat of sealer. Has the surface lost its sheen? Does water soak in rather than bead up on top? Is the finish beginning to show signs of wear? If the answer to all of these questions is yes, it’s time to reseal.

Often all you need to do is to give the concrete patio a good soap and water cleaning, followed by a light reapplication of the same sealer used initially. However, if you are switching to a different brand or type of sealer, most manufacturers recommend removing all traces of previously used sealers because the products may not be compatible. Never apply a solvent-based sealer over a water-based product because the solvent can eat away or soften the existing water-based sealer. For more information, read our guide to cleaning and sealing exterior decorative concrete.

What If Blisters and Bubbles Form on the Sealer Surface?

Blistering or bubbling of a sealer is rare, but it can really detract from the beauty of a decorative concrete patio when it occurs. The problem is usually caused when air or gases are trapped by the sealer during the curing phase, and is more common with solvent-based products. If the sealer dries too rapidly or too slowly or the top dries before the bottom (due to climate conditions or the sealer being applied too thickly), the potential is there to trap gas and create blisters.

For advice on getting rid of blisters and bubbles in concrete sealers and other troubleshooting tips, see Fixing Common Sealer Problems.