If you own a home in the Portland area, roof moss is not a rare problem. It is part of living in the Pacific Northwest. Long wet seasons, shade, fir needles, maple leaves, oak leaves, and organic roof debris all create the perfect environment for moss, algae, mildew, and lichen to grow. The confusion starts when homeowners try to figure out what to do about it. Some companies recommend brushing the moss off. Some recommend zinc sulfate. Some recommend roof soft washing. Some