Chalky Residue (Oxidation) On Siding
When I first started cleaning houses in the early 2000’s we would typically expect to see oxidation on all older houses with aluminum siding. Now it’s almost 20 years later and vinyl siding is much more common, we are seeing oxidation on these homes as well due to the age of the homes and the extreme seasonal weather and humidity we experience in our region. There’s a good chance if you wipe your hand on your siding you may see a chalky residue on your hand. Essentially Oxidation is the first step in the material breaking down, as nothing lasts forever.
Oxidation creates a chalky white substance on your vinyl siding and trim which occurs most often during damp or wet weather. This can leave a dull or uneven look to your home that can sometimes be more visible after a cleaning once all dust, mildew, pollen, etc. have been removed. In certain cases depending on the environment of the house (in the shade all day or exposed to the hot summer sun) certain areas of the home can be more oxidized than others and leave a slightly uneven look. Generally it is not that noticeable and sometimes can only be visible looking at the siding from certain angles.
During a low pressure soft wash cleaning we are mindful of this and do light rinsing as opposed to high pressure washing that can further damage the siding. The oxidation is not removed during this process as our washing is meant to remove mostly organic discoloration such as mold and mildew. This is purely a cosmetic issue and does not seem to affect the integrity of the siding itself.
For older homes that may still have aluminum siding this oxidation caused by weathering over the years may actually wear away the thin, colored finish and expose the aluminum color. In this case if replacing the siding isn’t an option it can be painted once it is cleaned to restore the color and a more uniform look.