When to Use Wall & Step Flashing

When a Roof and Wall Meet

• Not all homes have roofs that directly abut exterior walls. In some cases, the roof simply overhangs the walls with no point of contact other than the eaves. However, other roof designs have one or more locations where the horizontal pitched roof ends at a vertical wall. Step flashing uses a 90 degree bend in a sheet of thin aluminum to cover the joint between the two surfaces. Other types of flashing cover other joints and corners, but step flashing is necessary only where a roof meets a wall.

During Construction

• The easiest time to use wall and step flashing is during a home's initial construction or when you install a new roof. Step flashing can be installed after the fact, but the process requires removing shingles and siding from the home. This makes the entire process take longer and may force you to buy new shingles or siding if any material is damaged during removal. Installing step flashing during roof repairs ensures that you won't need to add it later when leaks become a problem.

Weaving Flashing and Shingles

• While installing a roof, you must add step flashing periodically as you lay shingles. Covering an entire joint with step flashing before any shingles are in place won't provide the best protection. Instead, install a single piece of step flashing and move on to adding the row of shingles that overlap that piece. Before adding shingles that extend beyond the flashing, add another piece of step flashing that overlaps the previous shingle. This is known as the weave method. It ensures that shingles and flashing alternate in layers and force water to run down the roof's pitch, away from the gap between the roof and the wall.

After Discovering Damage

• Use step flashing to protect problem areas of your roof where you observe water leaking into your attic or detect damaged flashing. When you install new siding on your home you'll expose existing step flashing. If the flashing is loose or damaged, replace it to avoid problems with leaks in the future. If water enters your home near the location of a joint between a roof and an exterior wall, use step flashing to add protection and prevent a perpetual leak.