Quiz ten facility managers about commercial power washing and commercial pressure washing power wash parking lot, and eight will say they're the same thing. They aren't. Close cousins, sure. Twins? No.
Force is the whole point of pressure washing. That's all it is. A pressure washer shoots cold water through a narrow nozzle at high PSI, and the stream itself does the scrubbing. Power washing adds heat. The water gets cranked up to roughly 200 degrees Fahrenheit, and suddenly grease, gum and oily grime give up without much of a fight.
Heat changes everything
Picture a greasy frying pan. Cold water just bounces off it. Hot water with a bit of soap? A whole other story. The same logic applies to a restaurant's back alley, a fast-food drive-thru lane, or the loading dock behind a grocery store. Oil soaks into concrete like coffee into a paper napkin. Heat breaks that bond. Cold pressure alone mostly shoves the mess from one corner to another.
When cold pressure wins
Heat isn't always the hero. Painted siding, wood decks, older brick, vinyl and some roofing materials can suffer under hot water. One contractor once told me it's like "cooking the surface," and frankly, he wasn't far off. Soft materials do better with lower PSI, cooler water and a patient hand. Wide fan tips. A good distance. Gentle passes. Rush it and you'll etch stripes into the surface that no amount of scrubbing will ever erase.
Picking the right method
Look at what you're actually fighting. Grease, oil, chewing gum, heavy mildew? Go hot. Dust, pollen, light algae, tire scuffs in a parking garage? Cold pressure is often plenty, and it costs less. Lots of properties need both, depending on the zone. A hospital entrance and its dumpster pad are two very different problems, so treat them that way.
Questions worth asking a contractor
Don't just ask for a price per square foot. Ask what PSI they'll use on your surface. Ask whether they run hot water units. Ask how they handle runoff, because in many cities you can't simply let dirty water flood the storm drain. Reputable crews use reclamation mats or vacuum recovery. Ask for proof of insurance too. One slipped wand through a glass storefront costs more than a whole year of cleaning.
A good crew will answer without squirming. A shaky one will say, "We just blast it." Walk away. Fast. Your building deserves better than a guy with a hose and big dreams.