Stains on vinyl siding

Algae

Stains on vinyl siding comes in many colors, with green, black, brown, grey any orange being the most common. Most of these stains are caused by algae.

Algae can be found on any type of siding, but we will concentrate on vinyl siding for this discussion.

You’re probably wondering how algae can survive on plastic or vinyl siding. The algae is feeding on sugars, dust, dirt or other things that are attached to the siding.  Many people are unaware that trees, both evergreen and deciduous, often broadcast ultrafine aerosols of sugars at different times of years. Park your car under certain trees and you’ll discover thousands of tiny droplets of sap or sugar on the painted finish and glass. Mix in dirt and dust that is blown around by the wind, and a smorgasbord has been set up for the algae.

Most of the stains on vinyl siding caused by algae will be on the north or east side of buildings or behind bushes. This is because these areas are shaded most of the day and stay damp longer. Great growing conditions for algae.

 Cleaning the stains off vinyl siding.

The good news is that algae can be washed off vinyl siding. We have cleaned stains from vinyl siding that comes off easily and some that need some scrubbing with a soft brush. One thing we have noticed is that home owners that have their homes pressure washed need to have them cleaned more often. Why this is may be that people using pressure washers may not be using detergents, just pressure to blast off the stain. This does not do a good job of cleaning off all the dirt and food for the algae that is embedded in the siding.

Our soft wash way of cleaning vinyl siding relies on the proper detergents to break the bond that dirt, algae and other contaminants have on the siding. Then we can safely rinse all the stains away with a low pressure rinse.

Algae is not the only culprit that stains siding. We will discuss some of the other causes in future blogs.