These tips will help you successfully clean and/or paint your siding to make it look like new.
Wash it. Washing the siding by hand with warm water and car-washing detergent will do the job, but power washing is faster and more convenient. Power washers, much like the sprayers found at do-it-yourself car washes, can be rented from home centers or rental shops. High-pressure sprayers that can be connected to garden hoses are available at hardware stores and home centers.
Remove the oxide. Aluminum surfaces may require some extra work. With aluminum, the coating can begin to erode and chalk; if the metal becomes exposed, it can oxidize. If aluminum siding has oxidized, you will need to remove the white residue carefully with steel wool or sandpaper, then give the surface a thorough cleaning. Do not try this with vinyl siding because it will cause deep, irreparable scratches.
Kill the mildew. Mildew is a common problem under porch ceilings, eaves, or soffits. To kill it, apply a diluted bleach solution, then rinse until it is clean.
Pick the right paint. To get the best results, spend a little extra money for superior paint. You'll get a durable and long-lasting finish from a top-quality acrylic latex paint. It's designed to adhere steadfastly to any factory-finished siding, preventing such common paint problems as peeling, blistering, and flaking. The flexibility of acrylic latex allows it to expand or contract with the siding as it heats or cools during daily and seasonal temperature changes. Quality paint may cost as much as $25 per gallon.
Many paints also contain additives that resist mildew and ensure uniform coats, allowing you to reproduce the appearance of the original siding.
If aluminum siding is dented, use a flat finish to help hide the damage.
If you have vinyl siding, don't choose a dark paint color. Dark colors absorb more heat from the sun and can cause vinyl siding panels to buckle.