Pressure Washing a Home Before Painting

Painting a house is a significant undertaking, but the finished result can be quite rewarding. After any remaining paint has been stored and the work is finished, it is satisfying to know that the property will not require another coat for many years. 

However, if pressure washing is not performed prior to painting, the results can be disappointing. Foregoing this step leaves behind a residue that prevents the paint from fully adhering to the surface. When chalky residues and dirt that were not removed begin to loosen, they often take the overlying paint with them. 

High-Pressure Rinse to Remove Debris 

Before the deep cleaning process begins, any large, loose debris should be sprayed off and the entire surface wet. A moderately high-pressure tip should be used—one strong enough to break up dirt and debris without damaging the siding. 

In most cases, a green (25-degree fan) tip or a yellow (15-degree fan) tip is appropriate. Red tips (0-degree) are extremely concentrated and should not be used for siding, as they can cause severe damage. 

To ensure safety, the operator should use a yellow or green tip and start at about 10 feet, moving in closer as needed for greater impact. Because pressure decreases the farther it travels from the spray gun, the operator can find an adequate balance of force and distance to use again in later steps. All areas intended for painting should be covered thoroughly to ensure no spots are missed. 

Low-Pressure Application of Appropriate Detergents 

Using a low-pressure tip, such as a 4.0 size (typically black) or a 40-degree white tip, detergent should be applied using a detergent tank or a separate bucket. 

Some pressure washers include a tip specifically designed for detergents, often labeled "soap." Using this tip, the detergent-and-water mixture should be sprayed evenly in an upward, sweeping motion to ensure even distribution. 

An eco-friendly, neutral-pH detergent is recommended to minimize damage to siding and surrounding plants. If the weather is mild and there is no direct sunlight, the detergent solution can be left to settle for approximately 10 minutes. If it is especially hot or the area is in direct sunlight, the solution may dry too quickly and should be reapplied after a few minutes or rinsed sooner. 

High-Pressure Rinse to Remove Tough Stains 

Once large debris has been removed and the detergent has had time to loosen deep-down dirt, the surface is ready for a final rinse. The previously used high-pressure settings should be used to safely remove stuck-on grime. Starting from the point where the detergent was first applied, the operator should work through the same pattern using an upward sweeping motion. 

Rinsing should continue until all detergent and dirt appear to be gone. Spot-checking the surface for any stubborn residue is recommended. Once the siding is completely clean, nothing will remain to prevent the paint from adhering properly. 

Let It Dry Completely Before Painting 

All sides of the house must dry completely before painting begins. While this may seem obvious, certain types of siding dry faster than others. Wood siding, for example, takes significantly longer to dry than vinyl or aluminum. 

Bare wood should feel completely dry to the touch, and wood siding specifically should be left for at least 24 hours to ensure no moisture is trapped under the paint. Once dry, the painting process can begin. Cleaning and drying the home properly ensures the paint job lasts much longer; while painting without pressure washing may only last 2–3 years, painting after a thorough cleaning can last up to 7 years.