What should I compare before assuming the source is in the Windows & doors? The safest answer begins by recording location, trigger and timing before assigning a cause.
What the question is testing
Openings combine drainage, seals, air leakage, thermal bridges and structural movement in a small visible zone. The question becomes more useful when it separates what happened first from what was noticed later.
A practical comparison
Record staining at corners together with weather, occupancy or system cycles. Repeat the observation only under safe, comparable conditions and note what stayed unchanged.
Limits and next step
Do not seal drainage openings or conceal active wetting. Broken glazing, unstable frames, rapid movement or water near electricity requires qualified repair. Use the connected atlas guide to build a bounded evidence packet and a clear professional handoff when needed.
