Moisture Intrusion
Domain 3: Moisture intrusion
This domain tests how water enters stucco and EIFS, what evidence it leaves, and how to report it without overdiagnosing concealed damage. The exam emphasizes pathways and the limits of a visual inspection.
Core rules
- Water moves by bulk flow, capillary suction, air transport, and vapor diffusion. In claddings, bulk water from openings and flashing defects usually causes the worst damage; air leaks can carry more vapor than diffusion.
- Drainage details matter more than surface sealant. Weather barriers, weep screeds, flashing laps, and clearances must form a continuous path to the exterior.
- Common entry points are grade contact, roof/wall intersections, window and door openings, deck ledges, utility penetrations, cracks, and failed sealant joints.
- Indicators include efflorescence, rusted accessories or fasteners, staining, bubbling or delamination, soft sheathing, musty odors, and mold. These are clues, not proof of the extent of damage.
- Moisture meters and infrared cameras can suggest wet areas, but readings through EIFS or tile can be misleading. Confirm with invasive evaluation when needed.
Worked example
A stucco wall shows a rust stain below a window corner and the finish sounds hollow when tapped. Reasoning: rust indicates prolonged wetting of a metal accessory; hollow sound suggests loss of bond or saturated substrate. The window corner is a likely entry point, but the stain does not prove the source. Report the observations, recommend moisture verification and repair by a stucco specialist, and note that concealed framing damage cannot be determined visually.
Traps
Do not equate a dry surface with a dry assembly. Do not rely on a single meter reading. Do not assume fresh sealant has solved an active leak. Do not report mold as certain from a stain.