Roofing: How to Install Step Flashing

Updated: Feb. 10, 2023

Why step flashing works and how to install roof flashing against a wall

FH11SEP_STEFLA_01-2Family Handyman
Continuous flashing is sometimes seen where a roof meets a sidewall, but in the long run step flashing will do a better job of preventing water leaks.

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Best roof protection

How to Install Roof Flashing Against a Wall: Step flashing

Step flashing redirects the water back onto the shingle. Even if one piece of step flashing fails, the flashing and shingle below it start the process over again.

Prevent Ice Dams

Continuous flashing against a sidewall is one way to install a roof, but it’s not the correct way. It may seem as if a single piece of flashing would offer more protection than many pieces of step flashing. But it doesn’t work that way. Once even a small section of roofing cement fails, you’ll have a leak. Each additional rain adds more water, and before you know it, you’ve got rotted wood.

Step flashing offers far better protection from leaks, because even if a single piece of step flashing fails, the water just hits the next lower piece. That flashing directs the water onto the shingle and the water drains down the roof.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Hammer
  • Tin snips
You’ll also need leather gloves

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Roofing nails
  • Step flashing