Flashing a chimney on an EPDM roof involves creating a watertight seal where the chimney meets the rubber membrane, using both counter flashing and step flashing. Counter flashing is installed on the chimney itself and typically overlaps the step flashing, which is laid in a stepped pattern along the chimney base. This combination helps divert water away from the chimney and the roof. Because EPDM is a flexible rubber material, it’s important to use compatible adhesives and ensure the flashing pieces are sealed properly without damaging the membrane. The process often starts with cleaning the surfaces thoroughly, applying an EPDM-compatible primer, and then using specialized tape or adhesive to fix the flashing to the roof and chimney. This layered approach helps prevent water from seeping under the membrane or behind the flashing.
To check your chimney flashing safely, look for obvious cracks, gaps, or peeling in the flashing or adhesive tape and inspect the seal where the EPDM membrane meets the chimney. If the flashing feels loose or water stains appear inside near the chimney, these are signs the flashing may have failed. A simple DIY test is to gently lift the edge of the flashing to see if the membrane underneath remains firmly attached; however, avoid pulling or using sharp tools that could puncture the EPDM. If you notice damage or persistent leaks, it’s best to call a professional roofer experienced with EPDM systems. When consulting a contractor, ask specifically if they use EPDM-compatible flashing materials and adhesives, and how they ensure the flashing remains fully sealed during temperature changes that cause expansion and contraction. This helps protect your roof warranty and ensures a durable repair.