How to Apply an Epoxy Coating to a Basement Floor
Epoxy coatings–or epoxy paint–are some of the toughest and best-looking floor finishes available. Learning how to apply epoxy to a basement floor is a time-consuming but gratifying DIY project. Depending on the state of your floor, the entire process can take 3 – 6 days.
How to Apply Epoxy to a Basement Floor: Step by Step
Epoxy application is a project that requires significant prep work to ensure success.
Step # 1 – Test Floor Suitability
An Epoxy application does not work if you find one of two situations – excess moisture or an existing concrete sealer. Here’s how to test for each.
Test For Moisture
To test if there is moisture present on your floor, place three or four pieces of plastic (about 18” x 18”) on the floor in various locations. Seal all four sides to the floor with painter’s tape and leave it undisturbed for 24 hours. After 24 hours have passed, pull the plastic up gently. If no moisture has accumulated on the underside, move on to the next step.
Epoxy is a hard plastic finish that prevents water from coming through the floor–once applied and dry. It will not adhere to moist surfaces.
Test For Concrete Sealer
Pour a couple of cups of water on the floor. If it beads up, you have sealer on the floor and cannot use epoxy. The two products are incompatible. You will have to use another floor covering.
Note: Newly poured concrete floors should not have a sealer on them. Do not apply epoxy for at least 30 days while the floor cures.
Step # 2 – Clean the Floor
A clean floor makes for a successful epoxy application. Spend as much time as necessary cleaning your floor. Any dust and debris remaining on the floor when applying the epoxy will cause bubbles and imperfections in your finish.
Remove any polyurethane or latex paint with a pressure washer and sodium bicarbonate. Let the floor dry and vacuum up any residue.
- Note: If you have drywall on the walls, tape poly over the bottom two feet to keep it dry.
Remove Oil and Grease
Degreasing the floor is more critical in a garage, but some basement floors may have grease build-up due to food spills. Most solvent-based cleaners will do a good job of cleaning.
If your family and friends are clumsy, mop the entire floor. Use a commercial degreaser if necessary. Let dry–then recheck the floor. Spot clean any tenacious areas.
If you find the remains of rubber furniture feet or rubber skid marks, sand them off using 180-grit sandpaper. Then, vacuum the entire floor again.
At this point, you are ready for the next step. If you are as anal as I am, mop the entire area again with clean water to ensure all the dust is gone.
- Note: To keep peace in the house and to do the best possible job, use a wet/dry shop vac. Not your wife’s vacuum.
Step # 3 – Etch the Concrete
Use a mop to dampen the floor with clean water. Do not leave puddles or overly wet spots. The floor has to remain damp during the etching process – dividing the floor into smaller sections works best.
In a pail, mix muriatic acid with water – ten parts water with one part acid. Pour the mixture into a plastic garden sprinkling can. A quarter gallon of acid mixed with water will etch 50 – 70 square feet.
Sprinkle the mixture on the floor and let it sit until it stops bubbling–about 10 – 12 minutes. Then, rinse the floor thoroughly with clean water. Leave overnight or until dry.
Note: Some muriatic acids require an application of baking soda and water to neutralize the acid. Read the directions.
Safety Notes: Muriatic acid–also known as hydrochloric acid–is dangerous. It can cause severe damage to the eyes, skin, nose, throat, and lungs. Put on the following protective gear before you open the container:
- Wear hazmat-type coveralls.
- Use a respirator.
- Wear safety glasses or goggles.
- Wear gloves.
- When mixing, pour the acid into the water. Not the other way around.
- Read and follow all directions.
Step # 4 – Fill the Cracks
Fill any cracks in the floor over a quarter inch wide with epoxy filler or hydraulic cement. You can address any smaller cracks with epoxy filler or window and door caulking. (Not silicone based.) Use a putty knife to work the products deep into the cracks and leave a smooth surface. Let dry completely (approximately 6 hours).
Note: Epoxy fillers and hydraulic cement only have a working window of about 30 minutes. Be quick. Both products also adhere to the surrounding concrete to prevent moisture penetration.
Step # 5 – Apply the Epoxy
Your floor must be 55 degrees F. or warmer for the epoxy to adhere – not the air temperature but the concrete temperature. Get this measurement with a non-contact infrared thermometer (not for human temperatures).
Turn off all gas and power. Wear gloves, eye protection, a respirator, rubber boots, and a hazmat-type coverall (if you prefer). Mix only enough epoxy as you can apply in 30 minutes since epoxy is only workable for 30 – 40 minutes.
Open all the windows to speed drying and get the odor out. You can also use a 20” box fan on high to help move air. (Run an extension cord to the main floor.)
Have your family leave the house for the day–especially if someone has asthma or is sensitive to strong odors.) Solvent-based epoxy off-gasses vile odors.
Applying the Epoxy
Before rolling out the floor, use a four-inch brush to apply epoxy at the walls and around any other immovable objects like your furnace.
Note: If you have baseboards on the walls, you can remove them to get epoxy tight to the drywall. Reinstall them after the floor is dry.
Use a ¾” nap roller with an extension handle. Start in the farthest corner and work back towards the door. Roll the epoxy out quickly but don’t be sloppy. Keep the roller wet. Mix up more epoxy as needed and continue working until the entire area is done.
After the epoxy coat application, let the epoxy dry for 24 hours. Then, perform another inspection for cracks, high spots, or low spots. Use sandpaper to knock down high spots and epoxy filler to fill cracks and low spots. Let the filler dry for at least 12 hours, sand smooth, vacuum, and damp mop clean.
Consider adding a commercial non-skid product to the second coat (3 – 4 oz. per gallon of epoxy). If you leave your epoxy untreated, it will be slick when wet. Apply the second coat of epoxy in the same manner as the first.
Let the second coat dry for 24 hours. Then wait another day for it to cure before walking on it. Don’t move furniture back on the floor until the epoxy has had enough time to cure.
Follow all of the directions on cans and packages. Make sure that safety considerations are first and foremost. Here are a few extra things to consider.
- Water-Based vs. Solvent-Based Epoxy. Both types are available in multiple colors. Water-based epoxy does not smell very much and cleans up with water. Solvent-based epoxy–once the preferred product–is falling out of favor as water-based gets better. Solvent-based product has a vile odor and is not as environmentally friendly.
- Colors. Epoxy is available in a wide variety of colors. You can also buy colored flakes to toss onto the drying floor.
- Epoxy Primer. Not every brand of epoxy requires a primer. Primer is best on chalky, porous, flakey, or rough floors to improve durability and bonding.
- Coverage. For each coat, it will take 2 – 3 gallons of epoxy to cover 450 square feet of concrete.