I think it's the Youtubers who claim how easy it is and make claims of making hundreds of thousands of dollars a year doing it. Somehow those videos made it into my algorithm on YT. Everyday for several months I get at least one usually 3 or 4 pressure washing / house washing videos recommended. I'm sure many other people are also. Seems like there are 2 bigger companies spamming Youtube with how to get in the soft washing business and that birthed a number of people who vlog on yt about how great the business is.
Edit: It also has a low cost of entry to start a pressure washing or soft washing company. From what I've seen you can start one for under $500 in equipment and have seen videos of guys using their cars to haul around the equipment and chemicals. So anyone who wants to can get into the business. On a side note I doubt many of them are licensed or have liability insurance. The risk of property damage is super high when running a pressure washing or soft washing business.
Friend's son did it -bought a pressure washer and started cleaning the neighbor's driveways on the weekends. 30 minutes, 50 bucks, not bad for an after work job.
You use a lower pressure and higher GPM than pressure washing. There are different ways to do it some people use a 12 volt pump with a flow between 5 and 10 GPM along with either a downstream injector or a mixing valve and separate tanks to inject SH (Sodium Hydroxide) and a surfactant (soap) into the wash stream. Other people use gas engine driven pumps the same as a pressure washer but the nozzle at the end of the line takes down the pressure of the water emitted from the pump so you don't damage the house. This is the most non-destructive and really the only safe way to "pressure" wash a house or roof. You can also use it on sidewalks and driveways. The SH kills organic matter and the soap breaks up dirt and grime. It is applied to the house and sits for several minutes then washed off with a stream of water.
I guess I could maybe imagine paying for that once every other year. But I think people underestimate how damaging pressure washers can be. Lots of folks have torn up their decks thinking they’ve “cleaned” them. People spray pressure washers UP at their house’s siding despite the fact that it is specifically lapped to repel water that is falling DOWN. And while concrete can stand up to a pressure washing, it will begin to develop any cracks you have if you do it frequently.
Yeah pressure washing is a blunt instrument. I pressure washed my deck and it got all splintery. Any sort of surface imperfections will be made worse by pressure washing.
I had a chemistry teacher who would put a chemical formula on the chalkboard and say things like:
“This’ll clean your teeth really well. Once.”
Or
“This’ll make your car go really fast. Once.”
That’s how I think about pressure washing a deck. It looks amazingly clean at first but the damage is there. Maybe sanding after would help. But you can only do that so many times.