Remove all items from the garage floor. It must be clean and free of loose paint, cement particles or any other foreign matter, before you paint. Place items outside temporarily so you have access to all corners, nooks and crannies of the garage. Use a wire brush and a solution of trisodium phosphate (TSP) to scrub the floor clean and remove any foreign matter on the surface of the concrete. If the floor is already painted, you will need to use a scraper to take off any loose paint and any stubborn surface matter. Vacuum the scraped-off paint and spray the floor with a pressure washer or hard spray from a hose, and then mop. Allow the floor to dry, and then thoroughly sweep the entire floor surface with a broom for good measure.
Always wear protective clothing when working with TSP. Follow manufacturer’s instructions carefully.
If you scrape, sand or remove any old paint, you may release lead dust. Lead is toxic. Exposure to lead dust can cause serious illness, such as brain damage, especially in children. Expectant mothers should also avoid exposure. Wear a National Institute for Occupational Safety and Health (NIOSH)-approved respirator to control lead exposure. Clean up carefully with a HEPA vacuum and a wet mop. Before you start, find out how to protect yourself by contacting the National Lead Hotline at 1-800-424-LEAD or log on to www.epa.gov/lead.
Remove any oil or grease on the floor with a degreaser. Apply the degreaser and scrub the stain with a stiff-bristle brush, and then wipe with clean rags. This is so the stains won’t cause discoloration or other problems with your paint job. Once you’ve finished cleaning, make any needed repairs to the floor.
Fix any cracks or holes in the masonry with a concrete patch or a hydraulic cement. Your local True Value associate can help you choose which product is best for your garage. Follow the manufacturer’s directions when applying the concrete patch or hydraulic cement.
Any moisture problems need to be taken care of before you can paint, so it’s a good idea to seal your masonry. Even if you don’t see any actual wet spots on your floor or walls, you may still have moisture hidden in the concrete. This could cause problems when you paint. Tape a few pieces of plastic kitchen wrap to different areas of the floor, making them as airtight as possible. Leave them overnight. If any condensation appears on the plastic wrap, you’ll have to seal the concrete. See Step 3 for tips on how to seal your concrete surfaces.