How to Epoxy a Garage Floor: Steps, Kits and Cure Times

Plan around the weather as well as the weekend. The coating sheet our calculator uses says to apply the product only when the air, the coating and the slab are all between 55 and 90°F, the slab is at least 5°F warmer than the dew point, and the relative humidity is no higher than 85%. Check the forecast for the cure days too, not only the day you roll.

You need a two-part epoxy floor kit, a degreasing cleaner, a concrete etch or a floor grinder, a concrete crack filler, a stiff scrub brush, a 9 inch roller frame with a 3/8 inch nap synthetic cover, a brush for the edges, a drill with a mixing paddle, a clean 5 gallon pail and painter’s tape. Add decorative chips if you want a flecked finish. For safety you need chemical-resistant gloves, eye protection and the respirator the product’s safety data sheet calls for.

The table shows what our epoxy calculator lists for its editable 1, 2 and 3-car presets, which assume 250 sq ft per car. Measure your own floor first, because garages vary. Primer is only for a floor that was sealed or coated before. The chip column is extra bags for a heavy broadcast, on top of the one bag in each kit. Two coats on the 2-car preset take 4 kits instead of 2.

Empty the garage, sweep it and scrape off anything stuck to the floor. Then remove oil spots, grease and spills and wash the whole floor with a degreasing cleaner, rinsing it well, as the coating sheet asks. Go over stubborn stains again. A coating cannot grip concrete that still has oil in it.

New concrete needs time before any coating. The coating sheet says to let new concrete cure for at least 28 days first. If your slab was poured recently, wait.

Sprinkle a little water on the bare concrete. If the drops soak in, there is probably no sealer. If they bead up, there is a sealer or curing agent on the floor. The coating sheet says it must come off by another method, such as sanding or grinding, before you coat.

Water rising through the slab can push a coating off. The coating sheet says the product is not for floors with a moisture problem. A quick screening check is the plastic sheet method (ASTM D4263): tape a square of clear plastic tightly to the floor and check under it the next day for damp or a dark patch. A dry result does not prove the slab is dry enough. A sheet for a fast-cure floor coating sets a measured limit of 3 lb of moisture per 1,000 sq ft over 24 hours by the calcium chloride test (ASTM F1869). If you see damp, have the slab tested before you buy a kit.

If the floor was painted before, wire-brush off loose or peeling paint and scuff-sand the rest so the new coat can grip. The EPA says homes built before 1978 are more likely to have lead-based paint, and it advises against removing lead-based paint yourself. Have old paint in an older home tested before you sand it.

Bare concrete needs a slightly rough, open surface for the coating to bond. The coating sheet behind our calculator calls for etching the bare floor with a concrete etch, then rinsing it and letting it dry. Follow the etch maker’s mixing, scrubbing and rinsing steps exactly, and wear gloves and eye protection.

Diamond grinding is the other route. The fast-cure coating sheet above prefers grinding to an 80 to 120 grit finish, a light profile called CSP 2 on the International Concrete Repair Institute scale. Grinding also removes sealers and old coatings that an etch cannot, but it makes fine dust, so use dust extraction and a respirator.

Fill cracks and holes with a concrete repair product and let it cure for the time on its label. Sweep and vacuum the floor, then let it dry fully before you open the epoxy.

The coating behind our calculator is solvent-based, and its sheet says all pilot lights and open flames must be out during the work and for at least 24 hours after. Open the garage door for air. OSHA notes that uncured epoxy can irritate skin and that people can become sensitized to it, so cover your skin and wash off splashes at once.

Stir each part, pour all of the activator into the base in the clean pail and mix for 2 to 5 minutes, ideally with the drill paddle. Do not stir the chips in. Let the mix stand for the time on the label, which changes with temperature, then stir again. The sheet lists a pot life of 2 hours at 70 to 80°F and 50% relative humidity, and says the usable time depends on temperature, so mix only when you are ready to roll.

Brush along the walls first. Then roll an even coat, working in sections about 4 by 4 feet so you can throw chips onto each wet section. Toss the chips up and away from you so they land flat. Keep a wet edge and make the last pass in each section in the same direction. For this product, the sheet says one coat is enough in most cases.

At 70 to 80°F and 50% relative humidity, the coating sheet lists light foot traffic after 16 hours, heavy foot traffic after 24 hours and vehicles after 4 days. Times at other conditions can differ, so follow the label for the kit you buy.

If you add a clear topcoat, follow its own instructions for when to apply it and how long it needs, which can add time before you park. Our calculator counts clear coat kits at 500 sq ft per kit for the product it cites.

Treat prep, drying, coating and curing as separate stages. With a 4-day wait before vehicles, the garage can be out of use for most of a week, so plan where the cars will go.

Before you buy, measure the floor and read the label, technical sheet and safety data sheet of the kit you plan to use. Check its coverage, how many coats it needs, whether chips come in the box and its temperature range. If it differs from the coating our calculator uses, work the kit count out again with that kit’s coverage.

Stop and ask a coating contractor if the moisture check shows damp, the slab has a sealer you cannot remove or old paint is peeling across the floor. Coating over those problems can waste the kit and the weekend.