Painting a Cinderblock Home
Cinderblock walls tend to look "unfinished" until they are properly painted, stuccoed, or covered with Elastomeric. Should you decide to paint your cinderblock walls, whether interior or exterior, there are several specific steps which need to be followed to ensure they finish beautifully. As with any painting, no matter the surface, it's absolutely necessary to properly prepare the surface prior to applying paint, and a cinderblock home is no different. Prep work is vital to the finished product, so don't be tempted to skip a step. Even if you have brand-new cinderblock walls which have never been painted, they will need to have the loose mortar washed away prior to sealing and priming. Painted interior walls will need to have the loose or peeling paint thoroughly scraped and brushed with a stiff wire brush. If your interior walls have any grease or oil on the surface, you will need to clean them with a trisodium phosphate solution, then apply primer which blocks any stains. For exterior walls, you will need to power wash the surface with a pressure washer which offers at least a 2000 psi. Any oil-based paint which was previously applied will need to be removed before new primer and paint can be put onto the surface.
Applying a Sealant
If you see lots of flaking paint on the interior cinderblock walls, it could be a sign of water seepage and damage, so your first order of business will be to determine where the water is coming in from or if it is simply seeping in through the pores of the cinderblocks. You will then need to make sure the area of leakage is repaired and sealed, or the concrete blocks themselves are all sealed with an appropriate concrete sealer prior to priming and painting. Before sealing your walls, patch any holes in the cinderblock walls with a hydraulic cement product which will harden within 24 hours. You will apply your waterproof sealer next, which is typically like a thin stain, and dries relatively quickly.
After applying your sealer to the cinderblock walls, and allowing it to dry, you will be ready to prime the walls, both interior or exterior. Make sure you have chosen a primer that is specially designed for concrete or masonry use, and if you are unsure, ask your paint department employee what they would recommend for cinderblock wall primer. While most primers are white, if you want to achieve a much more consistent color that has added depth, have your primer tinted the same color as the paint you intend to use, and allow your primer to dry thoroughly prior to jumping into the painting stage. Depending on the state of your cinderblock, you may need to apply two coats of primer to ensure full coverage.
There are many good brands of cinderblock paint such as DryLok or Sundry, and you will apply this product with a brush, as it is much thicker than your regular wall paint. Your first coat of sealant will need to dry for a minimum of twelve hours. Choose a special masonry paint brush rather than a standard paint brush, and rather than paint in a standard up and down pattern, use multi-directional strokes. Your first coat of paint will need a full twelve hours to cure. You will need to cover your cinderblock walls with a second coat, and possibly a third coat as well, allowing each coat to dry completely. The second and third coats can be applied with a thick nap roller, and you should paint the surface, whether interior or exterior, until you no longer see the brick pigmentation through the paint.
You also have the option to use an elastomeric product which is a kind of rubberized paint, and is generally sprayed on with an airless paint sprayer, although it can be rolled on as well. Typically, Elastomeric will have the consistency of thick sour cream, and if applied well, it will give you years and years of beauty as well as a waterproof surface which wears and weathers well. Elastomeric is fairly expensive, however, and you may want to have a professional apply it. Whether you paint or apply Elastomeric, your cinderblock walls can look new and fresh in merely a few short days.