Under the heading of "children don't try this at home," washing large surfaces either by pressure or power washing is highly effective, but can also be deadly and destructive if not done right.
What is the difference between power and pressure washing, you ask? Or maybe you didn't. You might not have even known there was a difference. But there is and it can be summed up in one word: heat.
Power washing has a heating element which makes it ideal for large and extremely dirty areas since heat dissolves grease and kills mold better than cold due to its higher kinetic energy. (I know, you thought this post wasn't going to require an understanding of molecular physics.) Pressure washing is ideal when you have softer surfaces that can erode or degrade from the heat of power washing.
In fact, power washing, while brilliant at removing chewing gum and killing off mold, fungi, mildew and weeds, can also dissolve sandstone and cedar, cause brick, concrete, and masonry to crumble, ruin a good paint job, destroy asphalt roofing, and remove stain from wood. The heat and pressure is terrible for anything old, regardless of material, and can create holes if applied with too much force.
Speaking of force, both power and pressure washing involve at least 2000 lbs of force exploding out of the nozzle which can be deadly if not dangerous. NEVER aim the nozzle at any living thing. NEVER. That level of force can kill people, plants, and animals. Power and pressure washing equipment require extreme caution when handling, which is why we started this post with "children don't try this at home."
However, if you do choose to try your hand at this, proceed carefully and slowly. Start by making sure you have the correct nozzle. Always wear safety goggles. Add soap, detergent, disinfectants, or other cleaning chemicals and let the area soak first (making sure you have the right soap for the material you are washing) and then rinse, staying five to six feet away from the surface and starting at the top so that the dirt above doesn't wash over the areas below.
While it's possible to do it yourself with a home system, this is one kind of job where having a professional is usually the smartest and safest call. If you need power or pressure washing for your business or home, Paige Blu Industries offers this as stand-alone or add-on service.