How to Secure Loose Roof Flashing

Roofing integrity begins and ends at the joints. Flashing is the metal barrier designed to protect the vulnerable gaps where your roof meets a vertical surface, such as a chimney or wall. When this metal begins to lift, it creates a direct path for rainwater to bypass your shingles and rot the wooden decking underneath. Catching this early is the difference between a simple afternoon repair and a structural nightmare. Working on a roof requires respect for the pitch and complete focus on your footing. You are not looking to build a new system here; you are looking to restore the mechanical seal that was lost over years of thermal expansion and contraction. Done well, your repair should be invisible, watertight, and flush against the masonry or siding.

  1. Clear Debris Thoroughly. Remove any loose debris, old dried caulk, or leaves wedged under the metal flashing using a stiff putty knife. Be careful not to pry the flashing away further than it already is, as you risk bending the metal permanently.
  2. Check Wood Soundness First. Check the condition of the wood framing behind the flashing with a screwdriver. If the wood is soft or feels spongy, the repair requires replacing the wood before securing the metal; if it is firm, proceed to sealing.
  3. Bed the Flashing Deep. Lift the edge of the flashing just enough to squeeze a bead of exterior-grade roofing cement beneath it. Press the metal firmly back down into the wet cement to create a primary moisture barrier.
  4. Anchor With Proper Spacing. Install roofing screws with pre-attached neoprene washers through the flashing and into the solid framing. Space your screws about 8 to 10 inches apart, ensuring you do not over-tighten and crush the rubber washer.
  5. Seal Every Fastener Head. Apply a small dab of roofing cement or an elastomeric sealant over the head of each new screw. This prevents water from weeping through the threads of the fastener over time.
  6. Inspect the Finished Seal. Check that the entire run of flashing sits flat against the surface. Wipe away any excess cement that squished out during the tightening process while it is still tacky.