- Always prepare a concrete block home before painting. Preparation ensures that your paint adheres to the concrete block and prevents water from entering and affecting the integrity of the block. Start by pressure washing your block home. Pressure washing clears the blocks' surface of dirt, dust and paint that otherwise would jeopardize the quality of your paint job. Apply the same preparation application for exterior and interior concrete block walls.
- Efflorescence is the white chalk buildup that sometimes develops on concrete blocks. It generally occurs in areas where paint is cracking and peeling, allowing moisture to get inside the block. You can remove efflorescence deposits with a pressure washer. Fill the water tank with masonry cleaner, and apply to the blocks. Then use a scrub brush to loosen deposits that remain, and power wash the blocks again.
- Use a commercial pressure washer that provides at a minimum 2500 pounds per square inch, or PSI, of water force for a wall that has been previously painted. A pressure washer with this level of force is sufficient for removing paint. Hold the tip of the hose about 12 inches away from the surface at a 15-degree angle, according to House Painting Info. Move the hose in a back-and-forth motion to clean the block. Do not attempt to repair loose mortar or cracks until the pressure washing is complete and the surface is dry.
- Rent or purchase a commercial power washer that offers up to 2000 psi. A power washer with 1500 to 2000 psi usually supplies enough pressure to get rid of dirt and dust on a new and unpainted concrete block home. Begin at the top of the home near the roof line. Move the hose in a horizontal fashion, and work down the wall until the blocks are free of debris. The spray tip should be about 12 inches from the wall and at a 15-degree angle to avoid damaging the concrete blocks while cleaning.
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