The core idea
Cladding is rarely the only water barrier; hidden layers must collect and drain water that passes the exterior surface.
How the mechanism works
A continuous water-resistive layer, flashings and drainage gaps redirect water to the exterior.
When it becomes relevant
Typical trigger: Wind-driven rain, aging joints or penetrations.
Evidence that supports this interpretation
- Damage appears below an interface
- Multiple cladding joints feed one area
- The cavity lacks drainage or termination details
Evidence that weakens it
- The wall remains dry through exposure
- The symptom is condensation-only
- A plumbing source is confirmed
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
Broad caulking can block drainage and worsen concealed wetting.
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.
US Department of Energy · government homeowner guidanceConsumer Guide to Air Sealing the HomeAir leakage, durability, comfort and ventilation coordination.Verified 2026-07-20 · review due 2027-01-20Open source ↗US Environmental Protection Agency · government guidanceMoisture Control Guidance for Building Design, Construction and MaintenanceMoisture sources, transport, design, construction and maintenance controls.Verified 2026-07-20 · review due 2027-01-20Open source ↗US Department of Energy · government research libraryBuilding America Publications and Solution CenterBuilding enclosure, HVAC, windows, indoor air and high-performance housing research.Verified 2026-07-20 · review due 2027-01-20Open source ↗
Observe→Compare triggers→Repair source→Verify outcome
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