Over time, the elements can take it toll on your exterior siding, causing it to fade and discolor. Your siding is under constant attack from the sun's ultraviolet rays, airborne pollutants, rain, snow, and the extreme yearly hot/cold cycle we see here in the Rochester MN area. The finish can chalk, fades and becomes porous which can allow dirt to penetrate the surface. Mildew can form in areas where the siding is damp or does not get much for sunlight, causing staining and discoloration.
You can make your siding look new and shiny with a little cleaning. Siding can be cleaned with a mixture of laundry detergent and bleach. The detergent will wash away the dirt, grime and chalking. The bleach will remove the mildew stains. A thorough inspection of you siding will help you determine the extent of cleaning you will need. There are commercially available siding cleaners that you can pick up at your local hardware store, or you can use a Spic and Span type product. Products like Spic and Span, 409, and Fantastic will work on both aluminum and vinyl siding. These products also rinse well.
Whatever detergent product you use, scrub the siding with a soft brush or sponge and rinse well. Do not allow the detergent to dry on the surface. To prevent stains on your siding, wash from the bottom up. Wet the siding with your hose and apply the detergent either with a brush or a garden sprayer. I like to use an automotive brush on a 6 foot handle. This allows you to work a larger area with less effort. You may have to let the detergent solution sit on the siding for a short period to help eliminate the more stubborn stains. Again, remember to not let the solution dry on the surface.
In areas of heavy mildew, you can try a concentrated mildew and mold remover called Jomax. Mix I pint of Jomax with 3 pints of laundry bleach and 2 gallons of water. Apply the solution with a garden sprayer and let it sit for 5 minutes. Scrub the area with your brush to remove any remaining debris.
Always make sure to follow any and all safety precautions for the cleaners you use. Avoid walking on the roof as it may become slippery as a result of the cleaners you are using.
A good cleaning can restore the beauty and natural colors of your vinyl or aluminum siding. You can also apply a product like Armorall or Penetrol if you would like to restore your siding's original gloss.