Black window-corner spots caused by a cold thermal bridge
Indoor humidity was only moderately high, but surface temperatures at the reveal repeatedly fell below the local condensation threshold.
✓Measurement Supportedrecorded confirmation level
01 / OBSERVED
→Black spotting around a bedroom window
02 / CONFIRMED CAUSE
→Cold window reveal and restricted air circulation
03 / REPAIR
→The reveal insulation and air seal were improved and furniture clearance was increased.
04 / VERIFY
Winter surface temperature rose and spotting did not return.
WHAT CHANGED THE DIRECTION
The evidence that separated the cause
Supporting clues
- Pattern followed the cold edge
- Worse behind curtains
- No rain correlation
Checks performed
- Surface temperature comparison
- Humidity logging
- Air leakage inspection
Field lessonRoom humidity and surface temperature must be read together.
