How to Pressure Wash Your Home Exterior Before Painting

Dirt, dust, and microscopic mildew are the natural enemies of a lasting paint job. If you apply fresh paint over a dirty surface, you are essentially painting over a layer of grime that will eventually flake away, taking your hard work with it. A thorough pressure washing creates the clean, bare substrate necessary for primer and paint to grip effectively. Done well, this process is about precision rather than raw power. You aren't trying to strip the wood bare, but rather removing the debris and chalky oxidation that inhibits adhesion. By taking the time to wash properly now, you avoid the frustration of peeling paint two seasons down the road.

1. Lock Down the House. Close all windows and doors securely. Cover exterior electrical outlets and light fixtures with heavy-duty plastic sheeting and secure them firmly with painters tape.
2. Coat with Cleaner. Fill the pressure washer detergent tank with an exterior house wash concentrate. Spray the solution onto the siding from the bottom up, allowing it to dwell for 5-10 minutes without drying.
3. Pick the Right Nozzle. Choose a 25-degree or 40-degree nozzle for siding. Avoid red (0-degree) or yellow (15-degree) tips, as these are high-pressure focused streams that can gouge wood or break siding panels.
4. Blast Away Grime. Start at the top of the wall and work your way down in overlapping, horizontal strokes. Keep the nozzle moving constantly to prevent water streaks or damage to the substrate.
5. Strip Every Last Trace. Switch to a clean water setting and rinse the siding from the top down. Ensure all traces of detergent and loosened debris are washed away completely.
6. Wait for Complete Dryness. Leave the house to dry completely for at least 24 to 48 hours depending on the weather conditions. Do not begin painting until the surface moisture levels are back to normal.