Synthetic stucco, commonly known as an exterior insulation and finish system (EIFS), is an exterior wall siding that consists of four primary components:
- Foam insulation boards attached to the exterior wall sheathing
- A base coat that is applied to the insulation board
- A fiberglass reinforcing mesh embedded in the base coat
- A finish coat applied over the fiber glass mesh
Although the EIFS may resemble stucco in appearance, the two siding systems are quite different, especially with regard to controlling water intrusion. The traditional stucco system anticipates eventual water penetration through open joints and cracks. To prevent rot and deterioration of the wood framing and sheathing in the exterior walls, it uses a housewrap or building paper behind the stucco surface to carry any water that accumulates in that area down and out the bottom of the wall.
The EIFS, on the other hand, was not designed for water intrusion. It was considered a surface barrier system because it resisted water penetration at its outer surface. It was assumed that moisture would not penetrate the surface and reach the wall sheathing and/or framing. The system was not originally intended to drain water that got behind the EIFS cladding. In practice, however, water did penetrate the wall, not through the surface but through jambs and sills of window frames, and at the joints between the exterior walls and door, window, deck, and roof intersections. Water that penetrated the wall could not easily escape. It was trapped between the EIFS cladding and the sheathing.
Over a period of time the water was absorbed by the sheathing and framing, which increased their moisture content to a level above saturation, causing rot and structural damage. Depending on weather conditions and the quality of construction, significant damage due to moisture intrusion could occur. Damage from water intrusion has been found in the exterior walls of houses that are only 3 to 5 years old.
The industry, recognizing the problems that resulted because of the lack of drainage in the wall, modified the system to include the installation of drainage channels and building paper between the foam insulation and the sheathing. In appearance the new system is similar to the old one, and with a visual inspection you cannot tell the difference between the drainable and nondrainable EIFS. Not only is the location of water entry often difficult to see, but moisture damage to the sheathing and framing behind the exterior wall cladding cannot be readily detected by visual inspection.
If the exterior wall cladding is an EIFS, you can do a preliminary inspection by checking for cracked and open joints at the interfaces between the EIFS and dissimilar materials such as windows, doors, and wall penetrations. If any are found that require caulking, record their location on your worksheet. Also, if you have a noninvasive moisture meter, check those areas for water intrusion. However, because of the nature of the potential problems and the high cost for correction, it is recommended that you have the exterior walls inspected and evaluated by a professional.
Weep holes (4' O.C.)