How To Pressure Wash A House?
QUICK ANSWER
Cover plants and electrical outlets with plastic. Apply house wash detergent from bottom up. Let dwell 5 to 10 minutes (don't let dry). Rinse top down at low pressure (under 1500 PSI for siding). Use a 25 or 40-degree nozzle held 12+ inches from the surface. Work in sections.
Pressure washing the entire house exterior is one of the more satisfying home maintenance projects; years of dirt, mildew, and pollution wash away in hours. The work requires careful technique to avoid forcing water behind siding (causing wall damage), breaking windows, or stripping paint. The general approach: bottom-up application of detergent, top-down rinse at low pressure. Here is the method that gets professional results without DIY damage.
What do you need to prepare?
Equipment: pressure washer (1500 to 3000 PSI suitable for siding), 25 and 40-degree nozzles, soap nozzle, house wash detergent (mildewcide formulation for biological growth), garden hose, ladder if needed for upper portions, plastic sheeting, plants, eye protection, gloves. Preparation: cover all electrical outlets, light fixtures, and AC units with plastic sheeting taped down. Cover or wet plants near the foundation; soap can damage them. Close all windows and doors. Remove or move outdoor furniture and grills. Check that all vents are not pointed at the house. Note any cracks or damaged siding that need attention before washing.
What detergent should you use?
House wash detergents formulated for exterior cleaning work best: Krud Kutter House & Siding, Mold Armor House Wash, Karcher House Wash. For DIY: mix 1 cup TSP, 1 quart bleach, 1 gallon water in a 5-gallon bucket; this is the contractor mix used by many pros. For homes with mildew or algae: oxygen bleach (OxiClean Versatile) is gentler on plants than chlorine bleach. Apply detergent through the pressure washer's chemical injector with the soap nozzle attached. The soap nozzle reduces pressure to allow safe detergent application. Avoid: harsh degreasers, paint strippers, or undiluted bleach on vinyl siding which can discolor.
What is the right technique?
Start with the soap nozzle and apply detergent from the bottom of the wall up to the top in overlapping passes. Working bottom-up prevents dirty soap streaks from running down dry siding. Let the detergent dwell 5 to 10 minutes; don't let it dry on the siding (mist with water if drying). Switch to the 25 or 40-degree nozzle for rinsing. Rinse from the top down, keeping the wand 12 to 18 inches from the surface and angled slightly downward. Work in sections of about 10 feet wide. Rinse plants when finished. Work on a cloudy day or in shade if possible; sun dries soap before you can rinse.
What should you avoid?
Never point the wand upward under siding panels; water forces behind panels and damages wall sheathing. Never use a 15-degree or 0-degree nozzle on vinyl or aluminum siding. Don't spray windows directly. Stay away from light fixtures and AC units. Don't pressure wash older homes with potential lead paint. For multi-story homes, hire pros; ladder work with a pressure washer is dangerous due to recoil.
Pressure washing a house transforms appearance and removes years of buildup. Right detergent, bottom-up application, top-down rinse at low pressure, 25 or 40-degree nozzle, 12+ inches from the surface. Cover plants and electrical outlets. For multi-story homes or homes with potential lead paint, professional service (300 to 700 dollars) is safer than DIY. The investment in proper technique versus rushing prevents thousands in repair costs from water damage to siding and walls.
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