Common household products make for some of the best liquid cleaners for routine vinyl siding maintenance. As with any cleaning of siding, test the cleaner on a small, inconspicuous section first to make sure adverse reactions do not occur with the specific variety.
All cleaners should be applied with a soft-bristled brush and rinsed clean with a hose. It is best to clean from bottom to top in sections 4 feet wide by 4 rows high. Rinse as the cleaning progresses upward and across the house.
Fantastik or Windex
These household cleaners are great at removing tough, but common problems that come from owning a home or having a family. This would include problems like bubble gum, oil-based caulking, felt marker stains, grass stains, car grease, rust, or topsoil are all best cleaned with Fantastik or Windex.
The grease-cutting powers, along with color-stay and non-bleaching properties make them ideal for washing irritating stains off small sections of vinyl siding. These cleaners can also be used for extremely small spots of mold or mildew. Often mold and mildew are a larger problem before they are discovered, rendering these cleaners better used for stain fighting.
Vinegar is an amazing cleaner that is astringent enough to cut through tough grime, acidic enough to kill mold or mildew, yet environmentally friendly enough not to harm children or pets. Using 30% vinegar and 70% water solutions you can clean large sections of vinyl siding of mold, mildew, or stuck on grease and gunk.
Vinegar's acidic nature is highly harmful to plants, however. The acidic nature kills plants but is often filtered through the soil. You should be concerned about vinegar water touching plants or leaves, but not just entering the soils around the house.
Make your own mixture by combining 1/3 cup powdered laundry soap, 2/3 powdered household cleaner (Spic-n-Span, Comet, etc), 1 quart of liquid bleach, and 1 gallon of warm water in a large bucket. Mix until all ingredients have dissolved. This multi-purpose cleaner is ideal for both grit and greasy accumulations, general stain-fighting, as well as mold and mildew.
The homemade solution is a great general-purpose cleaner once spot treatments for specific problems have been addressed. Though this cleaner will not adversely affect windows too terribly, try to minimize contact.
Trisodium Phosphate (TSP)
In a bucket mix 1/3 cup liquid laundry soap with 2/3 tablespoon and 1 gallon of warm water. This solution will clean just about anything off of the vinyl siding. It should be used with extremely tough rust, extensive mold and mildew, or extreme water discoloration.
Trisodium phosphate is an excellent household cleaner, however, it is incredibly poisonous. If using TSP make sure absolutely no contact is made with the skin, eyes, mouth, lungs, or just about anywhere else. Using an extending mop along with rubber gloves can help minimize any dripping of the TSP solution down hands or arms to the body. Keep children, pets, and plants away from any TSP solution and be sure to cover all glass windows as residue can cause permanent etch marks.