Power washing, or pressure washing, is the application of a high-pressure water spray to surfaces that need cleaning.

• It is used on concrete to remove mold, gum, and dirt stains.
• It is used on wooden decks to return the wood’s vibrant color.
• It is used on houses to remove pollution, mildew, and other problematic signs of aging.

For the majority of surfaces, an annual power washing should suffice. Depending on the current condition of the surface, you may need to increase the frequency of power washings. High traffic areas may need more frequent cleanings.

PSI is the pounds per square inch. This is what delivers the punch during a power wash, forcing contaminants off the surface.

GPM is the gallons per minute. This flushes the contaminants pushed off by the PSI.

Both are very important. Some people do, however, prefer more PSI or more GPM depending on their needs. A farmer may want more GPM to flush contaminants away from the fresh soil; a business owner may want more PSI to get the grime off the exterior surface of his or her storefront.

While power washing can be viewed as a do-it-yourself project, there is a clear distinction between a DIY crew and professional services. This means you get greater capability of equipment and greater expertise by having trained power washing technicians do it for you. 

A do-it-yourself washer may set the pressure too high for the surface or hold the nozzle too close to it. This can result in chipped painting, damaged screens, and ruined siding. And though most power washing equipment you can rent has the same PSI as commercial-grade tools, it holds a minimal amount of water—making this project take days, not hours.