As long as nighttime temperatures hover above 40 degrees, fall is the perfect time to paint your wooden porch floor.
Step 1: Prepare the floor surface by scraping away any loose paint. Fill large holes and cracks with an exterior-grade wood putty. If the existing surface is glossy, sand it thoroughly with 100-grit sandpaper. This will allow the fresh coat of paint to adhere properly.
Step 2: After the porch has been scraped, sanded and patched, clean it thoroughly with TSP (tri-sodium phosphate) cleaner and warm water. To protect vegetation around the porch, choose phosphate-free TSP to clean with.
Step 3: Select a floor and porch enamel made specifically for wood and concrete floors. Oil-base paints fortified with polyurethane will last up to four times longer than their latex counterparts. For outdoor areas, add a few drops of citronella oil to each gallon of paint before applying it to help discourage bugs from hanging around. For steps or slick surfaces, mix in a skid-resistant additive or a cup of silica sand to each gallon of paint to give the porch a slightly textured, slip-resistant finish. For extra traction on very slick areas, sprinkle silica sand directly onto painted areas before they dry.
Step 4: When there is no rain in the forecast and the porch is completely dry after cleaning it, use a thick, natural bristle brush to cut in the edges of the porch, around railing posts and along the wall areas. For bare areas on previously painted porches, spot-coat those areas with the floor and porch enamel before proceeding.
Step 5: Once the edges have been painted, roll or brush on the first coat of paint. Move from one end of the porch to the other, keeping the strokes straight and in alignment with the wood grain. Allow the paint to dry completely before applying a second coat in the same manner.
Avoid walking on the porch for at least 24 hours after you have applied the second coat of paint. Wait longer if temperatures are cooler or there is a fair amount of moisture in the air.