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What Is Step Flashing on a Roof and Why Does It Leak?

Last updated October 31, 2026

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The short answer

How Step Flashing Works

Step flashing protects the most vulnerable spot on your roof: the joint where a sloped roof meets a vertical wall. Each piece is tucked under the shingle above and bent up against the wall, creating a shingle-like overlap that sheds water downhill. The next flashing piece overlaps the one below, so water never hits a bare seam.

Without this interlocking pattern, rain runs down the wall and behind the shingles, soaking the roof deck and wall framing. Properly installed step flashing is a simple but critical barrier that keeps water out of the building envelope, especially during heavy rain or wind-driven storms.

Why Step Flashing Leaks

The most common cause of a step flashing leak is poor installation. If the flashing is nailed too high, too low, or not overlapped correctly, water can slip past. Over time, corrosion or damage from hail and debris can create holes or gaps that let moisture through.

Another frequent issue is missing counter-flashing on chimneys or walls. Counter-flashing is the piece that covers the top of the step flashing, and when it's absent or loose, water can enter from above. Roof movement from settling or thermal expansion can also pull flashing apart, opening small gaps that grow into leaks.

In regions with hot, humid summers and a hurricane season, roofs face intense sun, heavy rain, and high winds. These conditions accelerate wear on flashing and make proper installation even more important.

  • Check for rust or corrosion on visible flashing
  • Look for gaps between flashing and the wall
  • Inspect after severe storms or high winds
  • Watch for water stains on interior walls or ceilings
  • Ensure shingles overlap flashing properly
  • Have a roofer examine flashing during roof repairs

Signs of a Step Flashing Leak

A step flashing leak often shows up as a water stain on the ceiling or wall just below the roofline. You might also notice damp insulation, peeling paint, or a musty odor in the attic. In some cases, water travels along rafters and appears far from the actual leak point.

Act quickly if you spot any of these signs. Water that sits in wall cavities or on ceiling drywall can lead to mold growth and structural damage. The longer moisture lingers, the more extensive the cleanup and repair work becomes.

What to Do About a Leaky Step Flashing

Start by containing the water inside your home. This prevents the ceiling from collapsing and limits water spread.

Then, have a roofer inspect the flashing and surrounding shingles. They can re-seat or replace damaged pieces and add counter-flashing where needed. If water has already soaked into your walls or ceilings, you may also need water damage cleanup to dry materials and prevent mold.

Preventing Future Step Flashing Leaks

Regular roof inspections help catch flashing problems early. Have a roofer check the flashing whenever you have other roof work done, like after a storm or before hurricane season. Keeping gutters clear also reduces water backup that can stress roof edges.

If you're replacing a roof, make sure the contract includes new step flashing. Reusing old flashing is a common cause of leaks in otherwise new roofs. Proper installation now saves you from dealing with water damage later.

  • Schedule roof inspections after major storms
  • Ask about flashing replacement during roof work
  • Keep gutters and downspouts clear of debris
  • Trim tree branches that can scrape the roof
  • Check attic for signs of moisture or stains

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Frequently asked questions

Can I fix step flashing myself?

Fixing step flashing is tricky because it requires removing shingles and bending metal precisely. A mistake can make the leak worse. Unless you have roofing experience, it's safer to hire a roofer to inspect and repair the flashing properly.

How long does step flashing last?

Step flashing is typically made of galvanized steel, aluminum, or copper, and can last decades if installed correctly. However, corrosion, storm damage, or poor workmanship can shorten its life. Regular inspections help you replace worn flashing before it leaks.

Does insurance cover step flashing leaks?

Policies vary, and your insurer decides what is covered. Sudden storm damage may be covered, but gradual wear or poor installation often isn't. Check your policy and talk to your insurance company to understand your coverage. Keep records of repairs and maintenance.

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