Quality Control
Window Flashing Sequence
Install pan flashing, sill pan and head flashing in the correct order to prevent leaks.
9 min David Chen Reviewed by Maria Delgado, Technical Reviewer, PE v1.0 · reviewed 2026-08-30
The Problem
Leaks around windows discovered years later cause interior damage and legal claims.
Root Causes
- Flashing installed out of shingle order
- Backdam missing on sill pan
- Head flashing not integrated with WRB
Correct Procedure
- 1Install pan flashing with backdam and end dams
- 2Set window per manufacturer instructions
- 3Apply side flashings shingle-lapped over sill pan
- 4Install head flashing over side flashings
- 5Integrate all flashings with the weather-resistant barrier (WRB)
Discussion Questions
Use these to engage the crew and connect the lesson to today's site conditions.
- 1What is shingle order and why does it matter?
- 2How do we check for a backdam?
Sources & Review
Author: David Chen (22+ yrs) · Reviewed by Maria Delgado, Technical Reviewer, PE.
Published 2024-09-05 · Last technical review 2026-08-30 · Version 1.0 · Languages: EN, ES
AI at QST only summarizes expert-approved content and never invents safety requirements.
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