Most unfinished basements have a concrete floor. In its raw state, this material is usually unsightly. Many unfinished basements sit idle because homeowners aren't sure what to do with the space, but there are ways to make an unfinished basement much more welcoming and useful. A simple application of floor paint can be a quick, easy, and cost-effective way to make the environment more suitable for living space—especially for informal uses, such as a recreation room, workshop, or exercise room. If the concrete slab is smooth enough, a well-painted floor covered with good area rugs can be quite suitable for any number of uses.
Choosing the Right Paint
The best material for painting a basement floor is a two-part epoxy paint, which consists of an epoxy resin and a hardener mixed together. The hardening action involves a chemical reaction rather than evaporation, and the resulting surface is an extremely durable and chemical-resistant finish.
Another advantage of employing quality concrete epoxy in a basement is that it can help to waterproof the floor. The paint creates a tight membrane that will not allow water to pass through it, except under severe flooding conditions.
True epoxy paints are somewhat tricky to use since they produce toxic fumes that can be difficult to dissipate in the confined space of a basement. If you are using two-part epoxy, open all available windows and use fans to create cross-ventilation through the basement. Read the paint label carefully, and follow all recommendations for using breathing filters.
Many epoxy paints, and standard paints that are oil-based, produce fumes that are flammable. Take care not to use space heaters that produce open flames when painting with these products. Even gas water heaters or furnaces can pose a danger when painting a basement with epoxy or oil-based paint. The best method is to turn off gas appliances while painting; if supplemental heating is necessary, use electric space heaters that do not have an exposed heating element to gently heat the space.
Because two-part epoxy paints are somewhat difficult to use, many people prefer to use other types of concrete paints or floor coatings. Although some of these products also are labeled as epoxy paints, they are not true epoxies unless they include two parts that are mixed together.
If you use a one-part floor coating or floor paint, make sure it is labeled for use on concrete floors. These will be considerably easier to apply than epoxy, but you can expect to repaint the floor every five years or so since concrete floor paint is not as durable as epoxy.
It really makes no sense to paint a basement floor where flooding is a likelihood. Evaluate the floor and take whatever steps are necessary to prevent flooding. This may include sloping the ground soil around the exterior of the foundation away from the structure and ensuring that the gutters are clear and the downspouts are pointed away from the walls. If the home has drain tile and a sump pump, make sure they are in good working order. If flooding has been an issue and your home has no sump pump system, consider investing in one before embarking on any floor painting in the basement.
Since they are situated below ground level, basements often have high levels of humidity due to condensation. If there is too much moisture in the air, it can slow the rate at which the paint dries, or cause it to cure incorrectly. Habitually humid basements can be prone to peeling paint, as well as mold and mildew growing on walls and in rugs. If your basement is humid, consider adding a dehumidifier, both to assist the paint in drying and for making the basement drier and more comfortable as a living space.
Equipment / Tools
- Grinder or power sander with coarse sandpaper
- Vacuum cleaner
- Dehumidifier or fan
- Detergent (for cleaning)
- Old towel
- Paint tray
- Painter's tape
- Paint roller
- Roller covers
- Breathing protection, such as a mask or respirator
- Paint roller handle (optional)
- Concrete patching compound
- Concrete primer
- Epoxy concrete paint or concrete floor paint
Prepare a Smooth Painting Surface
If there are any cracks in the concrete, fill them using a concrete repair compound or patch product. These products are available both in pre-mixed form or as dry powders that are mixed with water; trowel on the repair compound and allow it to dry.
After applying the patching material, grind or sand the edges until they are smooth. If there are any raised surfaces, those should also be sanded down. Cracks and damaged areas will be glaringly obvious once covered with paint, and they can become tripping hazards.
Clean the Floor
Sweep or vacuum the surface of the floor thoroughly. Make sure there is no loose dirt or debris that will get trapped in the drying paint.
After vacuuming, mop the floor with detergent and water, then rinse with clear water to remove fine dust. Dry any visible wet spots with a towel, then let the floor dry for a full 24 hours with a dehumidifier or fan running. The floor must be completely dry before painting.
Prime the Floor
Though some epoxy products or floor paint are an all-in-one solution, others require priming the floor before application.
To apply primer to the concrete, use paintbrushes and a paint roller. Start at the wall farthest from the door, and work your way back towards the exit so that you don’t paint yourself into a corner. Use long strokes as you go, and try to apply the primer as evenly as possible over the entire area. If bubbles or puddles form, roll over them with a mostly dry roller to smooth out the application.
When you are finished, wait a full 24 hours for the primer to dry before moving on to painting.
Apply Painter's Tape
Before painting, apply painter's tape along the walls wherever they touch the floor. This will keep the color from spreading to unwanted surfaces and make the painting process much quicker. Two-part epoxy paints have a limited window before they begin to harden, so the quicker you can apply the paint, the better.
Mix the Paint Thoroughly
Follow the manufacturer's directions for mixing the paint. With two-part epoxies, mix a limited amount so the paint will not harden before you finish the application. One-part floor paints should be thoroughly stirred or shaken to mix the pigments.
Epoxy paint can emit strong fumes. This is especially worrisome if you're in a basement that doesn't have good ventilation. Always take care to use breathing protection, such as a mask or respirator, while mixing and using epoxy paints.
Paint the Floor
Use a paintbrush to "cut in" the edges of the floor adjacent to the walls. Immediately after this is done, begin rolling the "field"—the expanse of the floor inside the edges. As you did with priming, start in the areas furthest from the exit. Make sure that the coat is as flat and seamless as possible.
Apply a Second Coat of Paint
Let the first coat dry thoroughly, as instructed by the label directions, then apply a second coat of paint.
Lee S, Kim I, Park D, Song J, Lee SG. A case of acute organic solvent poisoning during epoxy coating. Ann Occup Environ Med., vol. 18, no. 31, 2019. doi:10.35371/aoem.2019.31.e9
Paint Handling and Disposal. Pennsylvania State University Environmental Health and Safety.