Define the question before measuring
Windows need layered flashing that drains incidental water outward even when outer sealant ages.
Capture a useful baseline
Record the exact location, date, current weather or equipment state, recent activities and the first visible, audible, sensory or measurable change. Keep one unaffected reference point.
Safe observations to repeat
- Record which corner wets first
- Inspect exterior joints from safe ground access
- Compare rain direction and intensity
Compare supporting and weakening evidence
Supports the pathway
- Water appears at lower corners
- Symptoms depend on wind direction
- Exterior joints or flashing terminations are suspect
Weakens the pathway
- Interior condensation forms uniformly
- Water is between panes
- A pipe above reproduces the leak
Interpret the result conservatively
Look for a repeatable relationship between trigger, location, timing and change. Treat exceptions as useful evidence rather than forcing every event into one explanation.
Escalation boundary
Window removal or cladding opening should be planned to preserve the drainage sequence.
Close the loop
If work is performed, repeat the same observation under a comparable trigger and through the original lag window. Record both recurrence and non-recurrence events.
Primary references for this topic family
These references ground the general building-science or safety context. They do not diagnose a specific house, replace local requirements or certify a repair.
