The most common mistake on siding is turning the pressure up. It is also the most expensive one.
Advice · EKL Cleaning
This is the single biggest misunderstanding we run into on exterior work. People see a pressure washer take years of grime off a concrete driveway in one pass and assume the same tool does the same favour to the side of their house. It does not.
Vinyl siding is thin, it is fastened in overlapping courses, and there is a wall behind it. High pressure aimed at siding can crack panels, force the courses apart, and drive water up underneath where it has no way to dry out. The damage often does not show up the day you do it. It shows up as a stain on an interior wall a season later.
On the wet side of the mountains, what dulls siding is usually not dirt. It is algae, moss and mildew taking hold in a climate that stays damp most of the year, plus general surface staining from road grit and pollen. Those are living growths, which matters, because the way you remove them is to kill the growth and rinse it away.
That is the reason pressure is the wrong lever. Turning it up moves your siding around while the algae stays exactly where it is.
Soft washing uses low pressure and the right cleaning solution instead of force. The solution does the work of breaking down the growth, and a gentle rinse takes it off. The siding comes clean and the panels, the seals and the wall behind them stay exactly as they were.
When we quote a house wash, matching the method to the surface is most of the decision. Cedar, vinyl and painted surfaces get a soft wash. Concrete, pavers and a garage floor can take real pressure. The same crew does both on the same job, with different settings, because the surfaces are different.
Pressure is only half of it. Using the wrong cleaning product on siding can leave streaks that will not rinse off, strip finish from anything painted nearby, and kill the plants in the beds underneath. Anything you spray on a wall runs down into the garden, so what you use matters as much as how hard you push it.
Walk the wall first and look at what you actually have. Note where the growth is heaviest, usually the north-facing side and anywhere shaded by a tree. Check for cracked or loose panels, because water finds those. Look at what sits under the wall, since the runoff is going there.
Worth knowing: heavy staining is often worse than it looks from the ground. On one exterior job we found the built-up staining ran far deeper than the quote had assumed from a distance. We stopped, explained what we had found, adjusted the approach, and finished it properly rather than rushing it or handing over a surprise bill at the end. Anyone quoting your siding sight unseen is guessing.
Exterior washing takes longer than people expect, and the reason is the water. Everything you take off the wall ends up on the ground, and dealing with that runoff properly is part of the job. A bigger house can run into multiple days. Anyone promising your whole exterior in an afternoon is skipping something.
Do not point high pressure at vinyl siding. Use low pressure and a solution matched to the surface, check the wall before you start, and think about where the runoff goes. If the growth is heavy or the wall is high, this is the point where most people are better off handing it over.
