Pressure washing can damage windows, window seals, vinyl siding, stucco. The first word after all is "pressure." Pressure washing can damage pretty much anything. That’s when people have to be careful where they’re using it. If your neighbor gets a new pressure washer and he does his driveway, the next day you will see the different light/dark spots that are left from his work. People have to be careful how much pressure, how close they get, what chemicals they use, etc.