How to Do a Knockdown Textured Wall

Scrub down your smooth walls with a detergent that contains trisodium phosphate, or TSP. Use a soft sponge and a bucket of water to remove all traces of surface stains, grease and soap. Let the wall surfaces dry while you prepare your room for the texture. Spread drop cloths over your floor, remove switch plate covers, lighting fixtures and electrical outlet plate. Tape over any windowsills or other permanent fixtures.

Mix joint compound, according to the instructions on the package. Pour the water and joint compound into a 5-gallon bucket. Blend the two ingredients into a smooth mixture with a large drill mixer bit that attaches to your power drill.

Connect the drywall texture spray gun to the hopper and compressor, according to the manufacturer’s directions. Scoop out enough of the moist joint compound to fill the hopper to the fill line. Set the spray nozzle on the spray gun and experiment with the pattern by spraying the texture over a scrap piece of lumber or large section of cardboard. Thin the mixture with enough water to provide a smooth and consistent spray.

Spray the wall with texture by starting at the top of the wall and moving the nozzle in a back-and-forth motion over the surface, creating an even spray across the entire wall.

Knock down the surface of the sprayed peaks while the texture is still slightly sticky, but not freshly wet. This generally takes between 10 and 30 minutes. Hold a large drywall knife at a sharp angle, almost laying the side of the broad blade against the wall. Pull the knife over the tips of the peaks to flatten them out. Avoid smearing the texture by wiping the blade off on a clean rag every few swipes. Complete the knockdown texture over your entire wall in this manner. Let the surface dry completely before you prime and paint the textured wall.