Flashing on a slate roof is crucial because it prevents water from seeping into vulnerable areas like valleys, chimneys, and vents. The best flashing details use durable metal, typically copper or lead, which ages well with slate and maintains flexibility. Flashing is installed in multiple layers, often with a step or counter-flashing technique, to direct water away from the roof structure. This layered approach helps avoid leaks caused by ice dams or heavy rain. A common reason flashing fails is due to poor installation or corrosion over time, which can lead to water damage even if the slate itself remains intact. For a simple DIY check, homeowners can look for signs like rust spots, cracked or lifted flashing, or water stains inside the attic or on ceilings. Running a water hose gently over the flashing while someone watches inside can also help spot leaks without risking walking on the roof.
If you’re unsure, it’s best to call a roofer experienced with slate roofs, since incorrect flashing repair can invalidate warranties and cause more harm. When speaking with a contractor, ask: “What type of metal flashing will you use and why?” and “How will you ensure the flashing integrates properly with the existing slate without damaging it?” These questions help confirm the roofer understands the delicate balance of durability and flexibility needed for long-lasting slate roof protection. A skilled roofer will also explain how their work complies with codes and warranty requirements, giving you peace of mind that your slate roof stays watertight for years to come.