Many people wonder if it is possible to paint the concrete foundation or stucco. Masonry surfaces are different from the wood or drywall in that they are more porous, they breathe, expand and contract, and they transfer moisture. These qualities make them a little trickier to paint, but they certainly do not make concrete unpaintable. You can paint a house foundation, basement walls, stucco walls, and even concrete floors.
The painting of the interior masonry surfaces is a little different from painting of the exterior ones. When deciding to paint the exterior of a foundation or exterior masonry walls, keep in mind the unique qualities of the concrete and follow the tips below. One more point: you might want to trim the grass and line the ground around the concrete surface with a drop cloth or something of the sort to protect the surface from picking up various particles.
Surface preparation before painting
As all good exterior painting contractors know, the quality of surface preparation will determine the quality and the lifespan of the exterior painting job. It is very important to clean the concrete of dirt, algae, mold or mildew, weeds, etc. The power washing will help you accomplish that. Of course, if the exterior surface to be painted has cracks, they need to be repaired first. Primer and paint will fill hair-like cracks. However, more significant ones should be patched with a concrete repairing filler first. If the surface has old paint, make sure no old cracking areas remain after power washing.
If the surface is very smooth, application of an etching product is advisable. Some acids, like phosphoric acid, are used for that. Be extremely careful and protect yourself when applying them.
Painting concrete walls
If the surface is damp after cleaning, let it dry completely. Depending on the weather and the surface location, it might take some time. For example, house foundation wall on the northern side of the house will remain moist longer, especially during the cold or humid conditions.
It is not necessary to apply a sealer when painting the exterior concrete. However, it is advisable to apply a concrete primer (also called a block primer) that fills the pores and evens the surface. It usually dries within a few hours. But it is better not to rush and wait for around 8 hours before painting.
Professional exterior painting contractors prefer to use exterior paint formulated specifically for concrete applications. It is thicker than the regular paint and has better expansion/contraction qualities to accommodate specifics of the masonry surfaces. However, the regular exterior latex paint should also do the job.
Apply a thin coat. Wait for the paint to dry (around 24 hours) and then apply a second coat if needed. Do not try to get it done with one thick coat as besides creating the pools and drips, it will affect the hardiness and protective qualities of the paint.
Because concrete is porous, you will need a thick brush and a longer nap roller (3/4″) to apply the primer and paint.
Exterior painting jobs on concrete walls freshen up a house exterior. Slightly different approach is required for the inside masonry surfaces, especially floors. Remember to apply some effort towards preparing the surface before painting and follow our advice. You will be pleased with the results.