Summer Project: Spruce up your Exterior Masonry
by Guy Randise, The DIY Guy
Do you want to bring new life to an old exterior wall? Want to improve the appearance of a concrete floor or car port? Consider a fresh coat of paint. But do it right; preparation is key.
Begin by power-washing the surface to remove old paint. If there’s mold on the surface, use the power washer with bleach. If you cannot use a power washer, or if you are working indoors, get rid of old, loose paint using a scraper and a wire brush. To ensure that your paint will stick well, use a scrub brush on the surface to remove any grease or oil or it will bleed through the paint, causing discolouration and possibly interfering with how long the paint lasts. Mix tri-sodium phosphate (TSP) in a bucket and scrub with the scrub brush.
Now would be a good time to repair any defects using a simple, ready-mix patch (see the manufacturer's recommendations on how long the patch should dry before being painted).
When choosing your paint, think ‘location’. Where will the paint be applied? Not only interior or exterior, but also because many manufacturers make specific masonry paints. Some are even designated as floor paints. There are now additives for your floor paint that provide a bit of texture or grip. This material is inexpensive and doesn't change the colour, but does prevent the slip that can occur when wet feet hit a slippery floor. Some kits come with decorative chips that are added as the paint is applied.
If using an oil-based paint and primer, don’t forget to buy mineral spirits or paint thinner to clean your brushes. While shopping, remember that most masonry surfaces need to be both sealed and primed before the paint is applied. The sealer keeps moisture from coming through the concrete. Choose a quality masonry sealer and a primer that complements it. Use the two-step process of sealing and priming to build a strong, water resistant foundation for your paint. Use a roller to do the bulk of the painting and a paint brush for cutting in along the walls if you’re painting a floor or drive. Make sure to read the manufacturer's recommendations as to what size nap to use. At least ¾-inch or 1-inch nap is recommended. Buy at least three covers, one each for the sealer, the primer and the paint.
Apply the sealer and primer coats first and, when they are completely dry, apply the paint. Use a paint brush to do detail work (around windows, trim or baseboards). Apply several thin coats, rather than trying to apply one very thick coat, as paint actually forms a harder surface when thin coats are laid on top of each other. One thick coat often results is a gummy or soft surface. This drying thoroughly is often called “curing.” It means that the paint has dried through all the layers down to the original surface. Paint dries to different thicknesses, depending on its sheen and makeup. The thicker the coat, the longer this process can take.
After your final coat of paint is applied, allow the paint to cure for the recommended time. If the paint is on the floor and you don't let it dry long enough, it may dry with footprints that will never go away.
Painting a masonry or concrete surface, be it walls or floors, inside or out, can give new life to your home. A space that may once have been dank and dirty can now look bright and clean.