Static field route #19618

What do I do when louver head flashing is reverse-lapped over the building wrap?

Sealing, Leakage, Mastic & Pressure Testing🛑 STOP / GET DIRECTIONField answer expansion

📖 Verified core answer

Reverse-lapped flashing sends water behind the wall protection. Stop and correct the shingle-lap sequence so water drains out, not into the wall.

Open in Field Rescue Open category

Field verification checklist

Check whether the weather barrier laps over the head flashing correctly.
Look for a reverse-lap path into the wall cavity.
Verify the exterior wall/envelope detail, not just the mechanical drawing.
Do not cover the condition with siding or trim.
Photograph the lap sequence before correction.

Ask foreman

The louver head flashing at [location] appears reverse-lapped with the building wrap. I checked the water path and it drains behind the flashing. Do you want this held for envelope correction before cover?

Text to foreman

Route options

A Correct it only if the fix is within your assignment and approved method.

B Hold and document if it affects water intrusion, weatherproofing, rated assemblies, structural anchorage, controls, TAB, or another trade.

C Bring the foreman/detailer the location, what you checked, and what decision you need before sealing, testing, cover, or startup.

Do not do this

Do not bury a reverse-lapped head flashing behind exterior finish work.

Why this matters

Wrong flashing sequence can cause hidden wall rot and major water intrusion.

Final verification

Use this as field training guidance. Final direction still comes from the foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, pressure/material schedule, and AHJ/code requirements.

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