By Kath4 from CT
The north side of any structure whether out in the forest or at home gets the mold, mildew and moss. The north side of anything gets the least amount of sunlight. I don't think you can prevent this as it's the sun that kills and prevents it from growing in the first place. Noella is right, that mold and mildew tells you where north is.
Drive around and you'll notice that happens with most buildings' north sides. Especially those that don't seem to have several hundred feet between them and the next building or fence. I've heard that out in the forest, that's how you can tell which way is north - by the fungus that grows on the north side of the trees. I'm glad to hear about the No-Rinse. I'm going to check it out for our garage.
I had this problem. I sprayed it with bleach in a spray bottle every week till it stopped coming back,good luck.
You can buy this at Home Depot, you won't be disapointed! You put it in a garden sprayer & spray it on once a year... then each time it rains, it binds with the rain to work. It's not harsh or bad for the enviorment. It's $40 for enought to cover 1000 feet. You dilute it 5 to 1.
Here's what they say:
Our revolutionary patent-pending, "No Rinse" concentrated cleaner that removes green and black algae, mildew, fungus, and lichen stains from roofs, siding, decks, brick, stucco, and other exterior surfaces. Spray & Forget is an eco-friendly, biodegradable, non-corrosive product that does not require damaging power washing and/or brushing techniques. In fact, no rinsing is required and your landscaping will not be compromised. Also an excellent preventative.
I searched the EPA website and couldn't find anything that specifically talked about mold on siding, but they do have a page where you can ask questions. Might be worth a try:
http://iaq.custhelp.com/cgi-bin/iaq ... XJjaF90ZXh0PWV4dGVyaW9y&p_srch=1
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