Step Flashing

What Is Step Flashing

Step flashing is a series of individual L-shaped metal pieces installed at the junction where a sloped roof meets a vertical wall, such as a dormer sidewall, a chimney side, or a second-story exterior wall. Each piece is typically 4 inches by 4 inches or 5 inches by 7 inches, bent at a 90-degree angle so one leg lies flat on the roof deck and the other leg turns up against the wall. The pieces are woven into the shingle courses one at a time, creating a stair-step pattern that channels water down and away from the wall at every shingle row. This method is far more reliable than a single continuous piece at a sidewall because each step independently redirects water onto the shingle surface below it.

Where Step Flashing Is Installed

Step flashing is required at every sidewall-to-roof intersection on a residential roof. This includes dormer cheek walls, chimney sides, second-story walls that bear on a lower roof, and any vertical surface that runs parallel to the roof slope. At the bottom of these intersections, a kickout flashing piece is installed to direct the last step of water into the gutter. At chimney sidewalls, counter flashing is typically installed over the step flashing to create a two-layer seal. The IRC requires flashing at all roof-to-wall intersections, and step flashing is the standard method for sidewalls on shingled roofs.

Common Step Flashing Problems

The most frequent step flashing failure is face-nailing, where the installer drives a nail through the exposed face of the step flashing rather than securing it under the shingle. This creates a penetration point that will eventually leak. Another common issue is insufficient overlap. Each piece should overlap the piece below by at least 2 inches; less than that allows wind-driven rain to get behind the assembly. Some contractors substitute a bead of roof sealant or caulk for step flashing entirely, which is a code violation and a guaranteed future leak. Debris accumulation in the corner where the wall meets the roof can also trap moisture against the metal, accelerating corrosion at the bend line.

Step Flashing and Insurance Claims

Step flashing is frequently damaged during wind and hail events. High winds can lift or displace individual pieces, particularly if they were face-nailed. Hail impacts can dent the metal and compromise its ability to shed water. When documenting step flashing damage for an insurance claim, photograph each damaged or displaced piece individually and note the linear footage affected. Xactimate uses line items priced per linear foot for step flashing removal and replacement. Pre-existing conditions such as corroded or caulked-over step flashing are typically excluded as wear and tear, so distinguishing storm damage from prior deterioration in photos and notes is essential for claim accuracy.