Outdoors Cleaning Tips, Guides & How To's

Green streaks and black spotting running down the shady side of a house are not dirt. They are algae and mildew feeding on a surface that stays damp because the sun never reaches it, which is why the same wall darkens every year while the south face stays clean.

That changes what to buy. A cleaner built to kill growth works differently from a detergent that lifts soil, and older vinyl carries a third problem, the chalky oxidation that comes off on your hand and needs a product meant for it.

The practical questions are whether a formula is safe over foundation plantings, whether it needs rinsing or is left to weather off, and whether a hose end concentrate is worth it against a ready mixed jug once you measure the wall you actually have to cover.

Technique decides the rest. Wash from the bottom up and rinse from the top down so streaks do not set, keep a pressure washer low and angled slightly downward so water is not driven up behind the panels, and take down webs and dirt dauber nests under the eaves first, or they end up smeared across clean siding.