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.