How to Paint a Basement Floor

Painted Basement Floor

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Most unfinished basements have a concrete floor/subfloor that forms the slab between the foundation walls. In its raw state, this material is usually unsightly, but a simple application floor paint can be a quick, easy, and cost-effective way to make the environment 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.

Floor-Painting Basics

The best material for painting a basement floor is a two-part epoxy paint, which consists of an epoxy resin and a hardener that are mixed together. The hardening action involves a chemical reaction rather than evaporation, and the resulting surface is extremely durable and chemical-resistant finish. Another advantage to employing a 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.

Safety Considerations

True epoxy paints are somewhat tricky to use, since they produce fumes that can be difficult to dissipate in the confined space of a basement. If you are using a two-part epoxy, make sure to 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 electrical space heaters to gently heat the space without open flames. This problem will not exist if you are using a water-based (latex) paint. But make sure to follow all label directions when using any paint.

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 "epoxy, " 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.

Tools and Supplies You Will Need

  • Concrete patching compound
  • Trowel
  • Grinder, or power sander and coarse sandpaper
  • Vacuum cleaner
  • Mop and bucket
  • Dehumidifier or fan
  • Concrete primer
  • Epoxy concrete paint or concrete floor paint
  • Paint tray
  • Paintbrushes
  • Painter's tape
  • Painter roller and roller covers

Instructions

The process for painting a concrete slab basement floor can be divided into broad categories of preparation, priming, and painting.

Preparation: Address the Potential for Flooding

It really makes no sense to paint a basement floor where flooding is a likelihood. Evaluate the floor and take whatever steps 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 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, you may want to consider investing in one before even considering floor treatments for the basement.

Preparation: Manage Humidity

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 dehumidifer, both to assist the paint in drying and for making the basement drier and more comfortable as a living space.

Preparation: Repair the Floor

If there are any cracks in the concrete, they should be filled in 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 patching material, make sure to grind or sand the edges smooth. Likewise, if there are any raised surfaces, those should be sanded or ground down. Cracks and damaged areas will be glaringly obvious once covered with paint, and they can become tripping hazards.

Preparation: Clean the Floor

Sweep or vacuum the surface of the floor thoroughly. Make sure that there is no loose dirt or debris that will get be trapped in the drying paint. Next, damp-mop the floor with detergent and water, then rinse with clear water to remove fine dust. Towel-dry any visible wet spots, then let the floor air-dry for a full 24 hours with a dehumidifier or fan running. The floor must be completely dry before painting.

Preparation: Manage the Temperature

Before beginning the painting job, adjust the temperature of the room so it is between 50 and 90 degrees Fahrenheit, which is optimal for drying time for epoxy paint. Consult the paint labels for precise information on the ideal working temperature.

Priming the Floor

If recommended by the epoxy product or floor paint, apply primer to the concrete. Primer provides the perfect surface for the paint to bond, and it is applied in the same fashion as standard paint—with paintbrushes and a paint roller. A long handle attached to a roller makes this work much easier. 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 completely before moving on to painting.

Painting: Apply Painter's Tape

Start by adhering painter's tape along the walls everywhere 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.

Painting: Mix the Paint

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 application. One-part floor paints should be thoroughly stirred or shaken to mix the pigments.

Painting: Apply Paint

Use a paintbrush to "cut in" the edges of the floor adjacent to the walls. Immediately after this is done, you can begin rolling the "field"—the expanse of floor inside the edges. As you did with priming, make sure you start in the areas furthest from the exit, so that you don't paint yourself into a corner. Make sure that the coat is as flat and seamless as possible.

Recoat the Floor

Let the first coat dry thoroughly, as instructed by the label directions, then apply a second coat of paint. Most paints require a full 12 to 24 hours to dry between coats, and this time may need to be increased if the humidity is high or adequate ventilation is not possible.