Silicone roof coating is a popular choice for waterproofing flat or low-slope roofs because of its flexibility and strong resistance to UV rays and ponding water. However, leaks around chimney flashing can still occur, often because the flashing wasn’t properly sealed before applying the coating or the silicone has developed tiny cracks or gaps over time due to temperature changes and roof movement. Flashing is the metal or rubber barrier that seals the joint between the chimney and the roof, and if it becomes corroded, warped, or poorly attached, water can find its way underneath the silicone coating and cause leaks. A simple DIY check involves carefully inspecting the area where the roof coating meets the flashing; look for bubbles, cracks, or any separation in the silicone. Also, check the flashing itself for rust, bends, or loose nails. Using a soft brush and soapy water can help remove dirt and reveal hidden damage without risking harm to the coating.
If you suspect a leak but don't see obvious damage, a safe way to test is to gently spray water around the chimney area and look for signs of moisture inside your attic near the chimney collar or ceiling. When you notice discoloration, dampness, or mold, it’s time to call a roofer experienced with silicone coatings and chimney flashing. When consulting a contractor, ask if they will perform a thorough inspection of both the flashing integrity and the coating condition before recommending repairs. Also, inquire about how they will re-seal the flashing without compromising the existing warranty on your silicone roof. A knowledgeable roofer should use compatible sealants and ensure proper flashing installation to prevent further leaks and preserve the roof coating's performance.