A green roof is a living roof system where plants are grown over a waterproof membrane, providing benefits like improved insulation, stormwater management, and extended roof lifespan. However, UV degradation can occur when the sun’s ultraviolet rays break down the materials used in the roof’s waterproofing layer, such as bitumen or synthetic membranes. This degradation causes the roof to become brittle, crack, or peel over time, potentially leading to leaks and damage to the plants above. The causes of UV degradation on green roofs often relate to poor initial installation, absence of a proper UV-resistant layer, or damage to the protective cover, sometimes exacerbated by extreme weather conditions. Homeowners might notice signs like dry, cracked membranes, pooling water, or the appearance of dead or unhealthy patches on the planted surface.
You can perform some safe DIY checks to spot early signs of UV damage without disturbing the roof too much. Start by inspecting the edges of your green roof for cracks or exposed membrane and look for any color fading or chalky residue on the surface materials. Check the condition of the drainage system to ensure water isn’t pooling, which can accelerate membrane breakdown. If you see irregular plant growth or dead spots, this could also indicate underlying membrane issues. While routine observation and gentle cleaning are safe for most homeowners, stepping on the roof is best avoided to prevent plant and membrane damage. If you suspect your waterproof membrane is compromised or the issue has progressed, call a professional roofer experienced in green roof systems. When consulting them, ask if the waterproofing membrane has a UV-resistant layer and what warranty covers UV-related damage, along with recommendations for repairs that won’t harm the plants or void your warranty.