What is window flashing?

Window flashing consists of metal or adhesive-backed tape installed around the edges of a window opening to channel water away from the frame, sill, and wall assembly. Proper flashing is essential for preventing water infiltration that can lead to rot, mold, and structural damage.

Flashing is typically applied in four locations around a window: the head (top), jambs (sides), and sill (bottom). Head flashing sits above the window frame, directing water down and outward. Jamb flashing lines the sides and works with the head flashing to shed water to the exterior. Sill pan flashing, the most critical component, slopes downward and outward at the bottom to ensure water runs off the building face rather than pooling or backing up into the wall.

Installation methods vary. Traditional metal flashing, often zinc or galvanized steel, is mechanically fastened and overlapped to create a water-shedding plane. Self-adhesive flashing tape, applied directly to the window frame or rough opening, offers easier installation and relies on the tape's seal to block moisture. Many Connecticut window installers use combination approaches, layering tape or metal flashing with proper slope and overlap to achieve redundant water management.

When installing new windows or replacing existing ones, correct flashing installation is as important as the window frame itself. Without it, water can bypass the window entirely and damage the surrounding structure.