The standard for a tough, good-looking surface on the garage floor is garage floor epoxy. Although it is common to hear people refer to “epoxy paint,” in reality epoxy and paint are different products, with different chemical compositions. And, while epoxy creates a tougher coating than paint, it is not without problems. Garage floor epoxy can yellow if it is regularly hit by sunlight. It is available in fewer colors than garage floor paint, and it is trickier to apply.
Application of garage floor epoxy can vary a little from product to product, so be sure to check the instructions on the product you choose. What follows are the standard preparation and application procedures for garage floor epoxy.
Inspect the Garage Floor
Garage floor paint is best applied to concrete that is clean, dry and free of serious cracks or damage. Cracks and small holes can be patched with concrete patch products before painting.
Moisture is a major cause of epoxy-coating failures. A concrete slab that has too much moisture content simply should not be covered with epoxy. There are two ways to check for moisture—one simple and semi-reliable, and the other a bit more complex and reliable. Before applying epoxy, I would recommend the latter. See Testing a Concrete Floor for Moisture for more information.
Clean and Degrease the Garage Floor
Use a broom and wet-dry vacuum to thoroughly clean debris from the floor.
Remove grease with a degreaser and stiff brush. Rinse the degreaser and allow the floor to dry. Heavy stains may require a pressure washer.
There are many manufacturers and dealers of garage floor epoxy, and there are different levels of quality to be considered.
Take a look at Choosing the Best Epoxy Floor Coating before you go shopping for your epoxy.
Etch, Acid Wash or Grind the Garage Floor
Epoxy bonds best if the garage floor surface has the texture of light sandpaper. Garage floors, however, are often troweled to a smooth surface. There are a couple of approaches to achieving a suitable texture.
The best way to prepare the floor is to scuff it up using a diamond grinder or a shotblaster. Both can be rented from home improvement or tool rental stores. The former uses diamond-coated sanding pads while the latter operates like a sandblaster. Both tools can prepare the concrete surface quickly and thoroughly. A less expensive but more time-consuming approach to the same end is to grind the surface with an angle grinder and masonry wheel.
The alternative to using one of these grinding machines is to etch, or acid wash, the concrete. Epoxy kits include etching formula, which should be used as directed. Pour the etching or acid mix on the floor, then work it in with a stiff broom or brush. It will foam and fizz, which tells you it is doing its job to abrade the surface.
Alternatively, you can mix one part of muriatic acid with ten parts of water.
Carefully pour the acid into the water, to minimize splashing. Wear eye protection and gloves when working with these liquids. After using muriatic acid, mix a generous amount of baking soda with water and pour it over the floor. This will neutralize the acid.
Once you’ve finished the whole floor, give it a thorough rinsing and allow to dry, preferably for several days.
Prepare the Room
Apply some wide painter’s tape along bottoms of walls. You may also want to tape some plastic sheeting to the bottom foot or two of walls. If it’s not too difficult, consider removing any baseboard, which would allow you to roll epoxy right next to the wall and eliminate the need to cut in the edges with a brush.
Mix the Garage Floor Epoxy
A two-part epoxy consists of a catalyst (or hardener) and a resin (the paint), which must be mixed together just prior to application.
Stir the paint a bit, then begin pouring the catalyst in while continuing to stir. Once the catalyst container has been emptied, stir for another two or three minutes until thoroughly mixed.
Put the lid back on the mixture and let it rest for the amount of time specified by the manufacturer, which will vary depending on the temperature. If you are using decorative color chips, do not add them to the mix.
Apply the Garage Floor Epoxy
As soon as the epoxy mix is ready, start applying it. For best results, wear spiked shoes. You will have no more than two hours to spread the epoxy, and even less time in hot weather. Keep the garage well ventilated.
Use a 3-inch paintbrush to cut in along the edges, then use a 9-in. roller with a 1/2-in. nap roller cover (with extension handle) to spread epoxy on the floor. Work in 10-ft. by 10-ft. sections. This work will go quicker if you have a helper handling the cut-in work. Maintain a wet edge by rolling over the edges of previously applied epoxy, and be sure to roll an even coating.
If you are using decorative color chips, apply them by hand over each section after you’ve spread the epoxy. Take a small number of chips in your hand and toss them up and out onto the floor. Again, a helper can speed this process up. For the second coat, wait at least 12 hours before application.
Apply the Top Coat
Some epoxy kit manufacturers claim that a single coat of epoxy is sufficient, but a second coat will provide longer service. Especially if you are using decorative color chips, adding a clear urethane top coat will produce better results.
Let the Garage Floor Dry
Don’t start walking on the new epoxy surface for at least 24 hours, and plan to wait at least several more days (and preferably a week) before pulling the car back into the garage.