The core idea
Cooking, bathing, sleeping, drying clothes and door habits can change moisture and air patterns without making occupants the cause of a construction defect.
How the mechanism works
People add moisture, particles and CO2 while operating fans, windows and appliances that alter pressure.
When it becomes relevant
Typical trigger: Weekends, guests, overnight occupancy or changed routines.
Evidence that supports this interpretation
- Symptoms follow repeatable activities
- Ventilation response is measurable
- Unoccupied periods provide a useful control
Evidence that weakens it
- The symptom occurs in an empty house
- Rain or plumbing dominates
- No activity relationship exists
What this concept cannot prove alone
A single observation, image or meter reading cannot confirm the complete failure pathway. Use this concept to form better questions, compare alternatives and decide which safe observation would be most informative next.
Safety and professional boundary
Occupancy data should inform ventilation and pathway analysis, not replace investigation of building defects.
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.
