Step Flashing vs Counter Flashing vs Kick-Out Decision Tree

Why this matters

Three flashing details meet at the most failure-prone interface in residential roofing: where a sloped roof meets a vertical wall. Step flashing rides each shingle course up the slope. Counter flashing tucks into the wall siding or behind a reglet cut in masonry to cap the step flashing. Kick-out flashing terminates the assembly at the eave to divert water away from the wall and into the gutter. Get one of these three wrong and the wall behind develops the most common hidden rot pattern in residential construction: failed step at the top, failed counter in the middle, missing kick-out at the bottom. The decision tree for a leak at a sidewall identifies which of the three failed first; the repair scope depends on the answer.

Symptom presentation

Three patterns at a sidewall leak:

• Water staining at the top corner of a window or wall feature below the wall intersection: failed step or counter flashing above; water has run behind the wall.
• Water staining at the bottom corner of the sidewall (low on the wall, near the gutter): missing or failed kick-out flashing; water ran down the wall instead of into the gutter.
• Water inside the wall cavity along the full length of the wall intersection: distributed failure of step flashing, counter flashing, or both.

Quick checks at the wall intersection

• Inspect the exterior from below. Visible step flashing should peek out between each shingle course where the roof meets the wall. Missing or wrong-direction step flashing is visible from the ground.
• Inspect the counter flashing. Properly installed counter flashing tucks into a reglet cut in the wall or behind the siding course above the step flashing.
• Inspect the kick-out flashing at the eave terminus. Properly installed kick-out flashing is visible as a metal piece kicked outward to divert water into the gutter.
• Inspect the interior wall behind the intersection. Wet drywall, stained drywall, soft drywall: water has been entering for a while.

Isolation tree

Step 1: where is the visible water damage?

• Top of the wall intersection: failed step or counter flashing above. Inspect the top courses.
• Middle of the wall: counter flashing or step flashing in that area. Inspect the visible flashing.
• Bottom of the wall, near the eave: kick-out flashing. Inspect the terminus.
• Multiple locations: distributed failure or a single source that has been entering for a long time and tracking through cavities.

Step 2: inspect step flashing condition.

• Step flashing is single pieces per shingle course, woven into the shingle layers, bent at 90 degrees with one leg vertical against the wall and one horizontal under the shingle.
• Missing pieces: step flashing was never installed, was removed during siding work, or has corroded out. Source-replace.
• Bent or damaged pieces: physical damage from ladder, ice damming, foot traffic. Replace.
• Step flashing installed but undersized (less than 10 inches per leg per NRCA): replace with properly sized.
• Step flashing installed but exposed at the bottom (not covered by next shingle course): re-integrate.

Step 3: inspect counter flashing.

• Counter flashing should cover the vertical leg of the step flashing, tucked into a reglet cut in masonry or behind the siding course above.
• Missing counter flashing with step flashing exposed: water enters at the top of the step. Install counter flashing.
• Counter flashing installed but lifted, separated, or with degraded sealant: re-seat or replace.
• Counter flashing installed but at wrong elevation (too low, not covering the step): re-set.

Step 4: inspect kick-out flashing.

• At the eave terminus of the wall intersection, kick-out flashing should be present, diverting water outward.
• Missing kick-out: water runs down the wall behind the siding. Install kick-out.
• Kick-out installed but inadequate (too short, no flare, plugged with debris): repair or replace.

Step 5: substrate inspection.

• Pull a section of siding at the suspected failure to inspect the substrate. Wet sheathing, rotten studs, mold growth: scope expands to include cavity repair.

Confirming diagnosis

Three confirmations:

• Photograph each flashing element. Document the failure mode at each location.
• Inspect from the interior side of the wall to confirm water path and damage extent.
• Test with hose-water if accessible per ASTM E1105 principles. Water at the suspected entry point should appear at the documented stain locations.

The repair scope is the failed elements plus any cavity damage.

Remediation by failure

Step flashing failure:

• Lift the affected shingle courses, remove failed step flashing pieces.
• Install new step flashing pieces per NRCA spec: 10 inches each leg, bent at 90 degrees, woven one per shingle course.
• Re-install shingles with proper nail placement; do not nail through the flashing leg.
• Document with photographs.

Counter flashing failure:

• Remove failed counter flashing.
• Cut new reglet in masonry (or remove and re-install siding course) per the assembly.
• Install new counter flashing covering the step flashing vertical leg.
• Seal the top edge into the reglet or behind the siding course with appropriate sealant per the substrate.

Kick-out flashing missing or failed:

• Install kick-out flashing at the eave terminus per NRCA spec or IRC R903.2.1.
• Integrate with the existing step flashing at the bottom course.
• Verify water diversion path into the gutter.

Substrate damage:

• Open the wall as needed to inspect.
• Repair rotten sheathing, replace damaged studs, address mold growth per S520 if present.
• Re-install siding, water-resistive barrier, and finish to match.

References

• NRCA Roofing Manual, Flashing Chapter, current edition
• IRC International Residential Code R903.2 (flashing requirements at walls and penetrations)
• IRC International Residential Code R903.2.1 (sidewall and headwall flashing)
• ASTM E2128, Standard Guide for Evaluating Water Leakage of Building Walls
• ASTM E1105, Standard Test Method for Field Determination of Water Penetration
• ICC International Code Council guidance on kick-out flashing (mandatory per R903.2.1 in current code)