Many cedar/redwood shakes roof homeowners were never told they need to maintain their roof to reach the potential natural life span of anywhere from 40 to 60 years. Normally after a 10-year period of not cleaning, a homeowner will notice the green moss or mold, the lichen or the dark brown to black coloration of fungi.
Read more on How To Maintain Your Cedar Shake Roof, by Bruce Sullivan, as an expert on Angie’s List.