Trees and bushes produce airborne sugars that drift through the wind and stick to vinyl siding. This nearly invisible layer of sugar is a food source for mold and some algae. Dust and dirt can also stick to the vertical sides of vinyl siding, and these are also food sources for some mildews and algae.
The best way to clean vinyl siding is to rinse it down with a regular garden hose equipped with a nozzle. Set the nozzle to a medium misting spray. Never use a forceful direct stream of water, as it can penetrate behind the vinyl siding. There are many homes covered with vinyl siding that do not have waterproof membranes that cover the frame walls. The wood sheathing and framing lumber can get wet easily if you direct water at the edges of vinyl siding, seams where two pieces of siding overlap, at inside and outside corners and next to windows and doors.
Vinyl siding is designed to shed water falling from the sky, not water that is shot up from the ground. Always rinse off the siding pointing the hose down towards the ground. Never aim a hose up at vinyl siding as it can cause massive amounts of water to seep behind the siding.
Regular dishwashing soap will do a fantastic job of cleaning vinyl siding. Squeeze a generous amount in a bucket, and add warm water to make a frothy mix of soapy water. I like to pour this water into a hand-pump garden sprayer to apply it onto the vinyl siding once it has been rinsed with clear water. Always work on a section of siding from bottom to top, and always work in the shade. You never want the soapy water to dry on the siding before it can be rinsed off. I prefer to clean an area about six to seven feet wide at a time.
Purchase a soft brush from a recreational vehicle (RV) dealership. They sell special brushes used on long poles to clean the sides of RVs. These brushes are superb tools to use on dirty vinyl siding. Once the vinyl siding has been coated with soapy water, dip the brush in the soapy water and use side-to-side motions to remove dirt.
Start cleaning from the bottom and go up as far as you can reach. Immediately rinse the area you cleaned. Proceed up the wall until you get to the top alternately washing and rinsing. As you get higher, always make sure you rinse all dirt all the way down the siding to the ground.
Never use chlorine bleach as an additive to your soapy water solution. Chlorine bleach is a deadly toxin for any and all vegetation around your home. The chlorine ions soak into the ground and kill the roots of the plants, grass, trees and bushes.
If you feel compelled to use a bleach to help kill the mildew, use oxygen bleach. Oxygen bleach is non-toxic, has no odor and it injects oxygen into the soil.
