Synthetic shake roofing often attracts algae and moss due to moisture retention and shaded areas, especially in humid or forested climates. These growths thrive where sunlight is limited and water lingers on surfaces. Algae typically appear as dark streaks or spots, while moss forms a fuzzy green carpet. Both can degrade the aesthetic appeal of your roof and, over time, may contribute to moisture issues if left untreated. It’s important to understand that synthetic materials are generally more resistant to damage than natural wood shakes, but algae and moss can still cause discoloration and, in worst-case scenarios, trap moisture that leads to the deterioration of underlying layers. Diagnosing algae or moss is as simple as visually inspecting your roof, especially after damp seasons or in shaded areas. You can safely perform this check from the ground with binoculars or carefully from a ladder, being cautious not to damage the shingles or compromise your safety.
For a quick DIY fix, gently cleaning affected areas with a garden hose or a soft-bristled brush can help, but avoid pressure washing, which could damage the synthetic surface and void warranties. Some homeowners use a mild solution of water and bleach or specialized algae-killing products designed for roofs—always following product instructions and testing a small area first. If algae or moss persist or cover large areas, it’s time to call a roofing professional. When consulting a contractor, ask about the best algae-resistant treatments safe for synthetic shake and whether their recommended solution maintains your manufacturer’s warranty. Also, inquire about the roof’s ventilation and drainage, as improving these can prevent future growth. A good roofer will provide clear guidance on sustainable prevention strategies along with effective treatment options.