The only real difference is heat - power washing uses hot water, pressure washing does not. Which one a Wilmington home actually needs, surface by surface.
The only real difference is heat. A power washer heats its water, usually to somewhere around 150-200 degrees; a pressure washer puts out the same pressure at whatever temperature comes out of the spigot. Everything else - the pump, the hose, the tips, the PSI - is the same machine. On the Cape Fear coast the honest answer for most homes is that neither one belongs on your siding or your roof. Those surfaces need soft washing. Heat and high pressure earn their keep on flatwork and grease.
Hot water breaks down anything oil-based, and that is the whole story. Grease on a restaurant dumpster pad, motor oil soaked into a garage apron, chewing gum flattened onto a sidewalk, wax and road film on concrete - hot water dissolves those in a way cold water simply will not, no matter how long you stand there. For organic growth, which is what almost every Wilmington exterior problem actually is, heat adds very little. Algae, mildew, and the black roof streaks are living organisms, and they are killed by the cleaning solution, not by temperature.
For the overwhelming majority of residential work here, a cold-water machine with the right chemistry and the right tip. The salt haze, the green film on the north side, the slick porch boards, the streaked roof - that is all biological growth fed by coastal humidity, and it comes off with a soft wash at 100-500 PSI plus a proper cleanser. Heat is worth paying for when the problem is oil or grease: an oil-stained driveway, a garage floor, a commercial pad. If a company quotes you hot water for washing vinyl siding, ask what the heat is doing, because on that surface the answer is mostly nothing - and hot water plus close-range pressure is one of the ways vinyl panels warp.
Yes, modestly. Hot-water rigs cost more to buy, burn diesel or kerosene while they run, and need more maintenance, so a contractor running one prices it in. In practice you rarely see it as a separate line item on a house wash - it shows up on commercial degreasing work and on stubborn concrete, where the surcharge over a standard cleaning is usually in the range of 20 to 40 percent. You can see how the surfaces price against each other on our Wilmington pressure washing services page.
Constantly, and that is worth knowing before you shop. Most homeowners say "power washing" when they mean any exterior cleaning, and plenty of contractors advertise both words on the same truck without owning a heated unit. The term on the ad tells you very little. The useful questions are what PSI they will use on your specific surface, what cleaning solution they apply, and whether they soft wash siding and roofs. Those three answers separate a careful operator from a risky one far better than the word on the sign does.
Flatwork is the one residential surface where the extra power is genuinely useful. Concrete tolerates 3,000 PSI through a surface cleaner, and that is how you get an even finish instead of the striped zebra pattern a hand-held wand leaves. Heat helps here specifically when oil, rust, or tire marks are in the mix. Pollen, algae, and general grey are cold-water jobs. Either way the work is the same visit for us under driveway and concrete cleaning.
Is power washing bad for concrete? Not when it is done right. Sound, cured concrete handles high pressure through a surface cleaner without trouble. Damage comes from holding a narrow zero-degree tip close to one spot, which etches the surface and leaves permanent wand marks.
Do I need hot water to remove black streaks from my roof? No, and you should not use pressure on a roof at all. Roof streaks are gloeocapsa magma, an algae, and they are killed chemically at very low pressure. Heat and pressure on shingles strips granules and shortens the roof's life.
Can I rent a power washer and do it myself? Most rental units are cold-water pressure washers, not heated ones - true hot-water rigs are largely commercial equipment. A rental is reasonable for a small patch of concrete. It is the wrong tool for siding, roofs, and second-story work, where the risk is both damage to the house and a fall.
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