How to Paint an Exterior Foundation

Clean the foundation surface thoroughly, removing any dirt or debris that might interfere with the adherence of the paint. Use a pressure washer to wash off the foundation, using as high a water pressure as possible without causing damage to the concrete. Wash the surface using a brush and a TSP cleaning agent. Sprinkle TSP onto the concrete, allow it to soak for 30 minutes, then scrub it away with a stiff brush. Remove any white crystalline efflorescence stains by scrubbing at the substance with a cleaner created from mixing equal parts white wine vinegar and warm water, using a wire scrub brush. Wash the surface a second time with the pressure washer, then wait 24 hours for the foundation to dry.

Place masking tape along surfaces adjacent to the foundation to avoid painting mishaps, including any driveway or sidewalk running alongside the foundation. Drape a drop cloth along the ground at the base of the foundation as well.

Prime the foundation surface with an acrylic block fill. Cut in the primer from the edges using a paintbrush to apply a strip about 3 inches in thickness. Fill in the rest of the surface of the foundation once you've completed the edges, using a thick-nap paint roller. Use multiple layers of primer to get a solid covering if necessary, then wait overnight for the primer to dry.

Apply your top coat of paint over the primer using vinyl enamel for good adherence to the concrete and to create a hard paint surface. Cut in the edges of the foundation with the paintbrush, then fill in the rest of the surface using the paint roller as you did with the primer. Apply two coats for even coverage, waiting two hours between coats.

Remove the masking tape and take up the drop cloths. Allow the final coat of paint to dry completely, according to the manufacturer recommended waiting times, before touching the painted foundation.