What is step flashing?

Step flashing is a series of overlapping L-shaped metal pieces (usually aluminum or galvanized steel) installed where a pitched roof meets a vertical surface such as a wall, chimney, or dormer. Each piece is positioned to overlap the roof shingles below it while the vertical portion slides behind the wall material or sits against the chimney face. The pieces are staggered so that water flowing down the roof is guided outward and downward, preventing moisture from collecting at the junction.

The main difference between step flashing and continuous flashing is coverage and flexibility. Continuous flashing is one long metal sheet that runs the entire length of the junction, while step flashing uses individual segments that allow the roof and wall to move slightly without cracking the metal or breaking the seal. This flexibility matters in the Hartford Metro climate, where temperature swings and settling can stress rigid connections. Step flashing also works better on sloped roofs because each overlapping piece channels water down the slope naturally.

Proper installation is critical. Each step must be nailed and sealed correctly to prevent water from running behind the flashing and into the wall or attic. Over time, step flashing can pull away from the wall, allowing leaks to develop. When installing or replacing a roof replacement, contractors must ensure step flashing is present, correctly positioned, and free of rust or damage.