Guided evidence worksheet
Thermal bridge condensation: cold line versus moving air
Compare the cold line with adjacent surfaces under the same conditions and test whether wind produces actual air movement.
Reasoning guardrail
Separate the routes before choosing a repair.
A cold surface does not by itself prove that outside air is entering.
- Trigger
- Surface temperature pattern and air movement are more useful than touch alone.
- Area
- Wall
- Provenance
- Original explanatory diagram, not a site photograph.
1. Freeze the evidence
What happened first?
2. Competing hypotheses
Record evidence for and against each route.
Thermal bridge through framing or fasteners
A solid material path conducts heat faster and creates a stable cold line on the interior surface.
Evidence that raises fit
Evidence that lowers fit
Notes
Air leakage at a joint or penetration
Outdoor air moves through a discontinuity and cools a smaller irregular zone.
Evidence that raises fit
Evidence that lowers fit
Notes
High indoor humidity amplifying a cold surface
Normal or moderate cold geometry becomes visibly wet because indoor moisture load is high.
Evidence that raises fit
Evidence that lowers fit
Notes
3. Decision points
Change one condition at a time.
Does wind change the temperature pattern or create detectable air movement?
Yes: Move air leakage ahead of a pure thermal bridge.
No: Compare geometry with framing and insulation continuity.
Observed answer and evidence
Are several cold surfaces condensing at the same time?
Yes: Treat indoor humidity as an important amplifier.
No: Keep the investigation local to the wall assembly.
Observed answer and evidence
Safety boundary
Stop rather than create a better clue.
- Use only a smoke pencil or tissue; never use an open flame for draft testing.
- Stop if condensation is near electrical devices or damaged wiring.
5. Current conclusion
