Painting a concrete retaining can be challenging. If some thought and planning is exercised before the project begins, the project will be a success.
The level of challenge of painting a concrete retaining wall is proportional to the height and length of the wall. Retaining walls, after a while, will attract dirt and grime and can be the target of taggers. If the wall has an untreated metal fence above it, the wall may suffer the wrath of rust washing off the fence, staining the wall. If taggers see the wall as their own personal canvas, the result is an ugly wall.
Painting supplies necessary for the job are rollers and handles, 2 or 3 inch wide paint brushes, paint trays and half gallon paint buckets, drop cloths and wipe cloths, wire brush, putty knife, paint can opener and mixing sticks. Be sure to have a one gallon bucket filled with clear water in case it is necessary to rinse off a paint brush or roller.
It will be necessary to wash the retaining wall before painting. If it is a fairly new wall, a wash down with the garden hose may be sufficient, but if the wall has been up for a while, the water will need some power behind it. Power washing will remove grime, grease and rust stains as well as loose particles or concrete scaling.
If detergent is used in the power washing process, be sure the product used is bio-degradable; otherwise, it may be necessary to provide secondary containment to catch the wash water for alternate disposal. Depending on the size and complexity of the job, hiring a power washing specialist might be preferable to renting a power washer and doing it yourself.
After the wall is washed, let it dry for several days. Concrete is porous, and the surface will hold water for a short time. If the wall has cracks or gouges and holes, fill in the cracks and gouges and holes with cement or masonry patching material. Smooth the patch work with a trowel or putty knife as much as possible to avoid “lumps” in the wall.
If the wall has been the victim of graffiti, power washing may not remove the paint entirely. Paint those areas with a paint sealer such as Kilz that prevents the paint from bleeding through the final coat of paint. It might be a good idea to paint the entire wall with primer to seal the pin holes in the concrete surface. If a primer is not used, it may be necessary to apply at least 2 coats of paint.
It Is Time To Paint
After the wall has dried sufficiently, pick a day to paint that will have a few dry days following. That will give the paint a chance to dry. Choose a quality latex exterior paint. Latex will stand up to harsh weather conditions better than a non latex paint. Always use drop cloths when painting and have a wipe cloth handy to wipe up any spills or drips.
The best way to paint a retaining wall is with a roller. Use an extension handle to reach areas above the comfortable reach of the painter. Use a 2 or 3 inch wide brush to fill in areas around the perimeter or places where a roller might not fit. If the concrete is scored, a brush can be used to paint the scores. A safety step ladder will help you paint smoothly the details at the ceil or the corner of the walls.
Paint the scores the same color as the rest of the wall or pick a lighter or darker color for the scores to provide contrast in the wall, if desired. Apply the paint in the same direction to avoid a patchy look. If the wall is large in area, a paint sprayer may be more efficient. After the paint has had time to dry, usually for a day or two, it may be necessary to fill in areas that might have been missed or received a scant coat of paint.
When Painting Is Complete
Clean the brushes, rollers and handles, paint trays and buckets in warm soapy water to remove excess paint before putting them away. If the paint dries before washing the items, it may require a special solvent to clean the paint off them. Let drop cloths and wipe cloths dry thoroughly before folding them up for storage. If paint is left over when the project is complete, secure the lids to prevent the paint from drying out