Please tell me what can be done to keep the green buildup off siding! What causes this? Can anything be put on the siding to deter it? Does insulation in the building have anything to do with it?
The green buildup is most likely algae that tend to grow in shady areas, particularly on the north side of structures. To grow on vinyl siding, besides moisture, the algae needs a food source such as dust, dirt or the sap and sugars from trees and shrubs near the home. Algae can also feed off some fertilizers used to treat lawns.
If you have a sprinkler system, check to see if it impacts the siding, because it can provide additional moisture that can accelerate algae growth.
When it comes to cleaning, there are specialized products designed for the treatment of algae on vinyl siding. Simple Green seems to be the choice for many homeowners, although a Tide mix or an oxygen bleach mix works well. If you want to use a home remedy, try mixing a solution of half water and half oxygen bleach with a small amount of trisodium phosphate to hand wash the siding. My friend Danny Lipford of todayshomeowner.com suggests using “1 gallon water, 1/3 cup powered laundry detergent and 2/3 cup TSP (trisodium phosphate) cleaner.”
Many reports I have read say the TSP helps to keep the algae off the siding for up to five years. When working with cleaners and chemicals, make sure to wear protective attire such as a long-sleeved shirt, long pants, gloves and eye protection. When using any chemical or cleaner near grass and plants, make sure to water the area affected both before and after cleaning. To protect any warranty that was provided with the siding products, contact the siding manufacturer for information on cleaning and maintaining its product.