Exterior Insulation and Finish Systems
Exterior Insulation and Finish System (EIFS) is a multilayered exterior wall cladding system that has been commonly available since the early 1980's. The substrate for the ElFS is a foam insulation board that is glued or mechanically attached to the wall sheathing. A reinforced base coating, which serves as a moisture barrier, is then applied directly over the insulation board. The final finish is provided by a durable stucco-textured coating made of synthetic and natural materials. This finish coating is often referred to as synthetic stucco.
The benefits of an EIFS product include design flexibility, variety in color and texture patterns, energy efficiency, and quick installation – compared to conventional stuccos products. The synthetic finish coat is also more flexible than conventional stucco and consequently less prone to cracking.
Other purported features of EIFS when first marketed included durability and weathertightness. However, in the early 1990s the validity of this claim became suspect when evidence of serious moisture intrusion problems surfaced with EIFS-clad homes, particularly many in the southeast coastal area of the United States. Initially there was controversy over whether the problems were related to inherent design flaws or installation deficiencies. In the end, it proved to be a combination of factors.
The end result of this combination of design and installation factors was water intrusion, wood-destroying organisms (decay) damage, and mold - often in hidden wall framing and sheathing, particularly under and adjacent to windows and other wall openings and roof runoff points. The primary cause for the infiltration was determined to be improperly sealed joints at the EIFS interface with trimwork and other components. Ironically, it was the moisture-retardant (water- barrier) features of some of the EIFS components that contributed to the problem, as any water that infiltrated past the surface became entrapped, eventually causing damage to surrounding wood components.
Significant structural damage can occur with repeated episodes of infiltration and when the wood reaches high moisture levels. In addition, moisture resulting from missing or improperly installed vapor retarders or other indoor moisture problems can add to the moisture entrapment conditions.
While the initial discovery of this significant concern with EIFS occurred in the warm, humid coastal areas, any EIFS structure is susceptible to similar problems. Unfortunately, these detrimental moisture conditions may go unnoticed until occupants experience problems associated with poor indoor air quality due to the presence of mold spores, invasive evaluations are performed, or extensive underlying damage becomes apparent with renovation work.
If a home appears to have an EIFS or similar cladding, it is generally recommended that an inspection of all exterior walls and surfaces, particularly at the windows, doors and other openings, be performed for evidence of inadequately sealed joints and/or signs of moisture infiltration or entrapment. Though many houses will not outwardly exhibit evidence of installation deficiencies or moisture intrusion problems, it still would be prudent for homeowners to have the house professionally checked by the product manufacturer and/or a qualified water intrusion specialist. In the majority of cases, detrimental conditions may only be detected after removal of some of the siding material. Buyers of homes with EIFS or similar wall-cladding system are also advised to arrange for a professional assessment of conditions, prior to closing.
As an outcome of the investigation into the EIFS problems, more precise installation instructions and warnings were developed by manufacturers. In addition, a new component was added to the layered system. This is a drainage grid that is applied to the sheathing before the insulation board is applied. This grid collects any infiltrating water and drains it to the base of the wall. This new design is referred to as a “water-management” system. Many building departments also require new EIFS installations be approved by a certified EIFS inspector.
Even an EIFS house with a water-management system or no evidence of moisture infiltration problems, will require periodic maintenance to minimize the chance of a future problems and to maintain product appearance. All caulking should also be checked regularly, and must be replaced or upgraded as conditions dictate.
The finish coating itself, while not normally needing paint, should be cleaned periodically to prevent staining. Power washing is a common cleaning method, however, care must be taken to ensure that only low pressure systems are used. High pressure power washing is more likely to damage the caulk or other components and allow water to infiltrate behind the surface.
Lawn sprinkler and roof drainage systems should be checked periodically to make sure that they do not direct any water onto the walls or trimwork. Shrubs should also be regularly trimmed to minimize the chance of moisture entrapment against the house.
Note: The issues discussed here primarily apply to EIFS installations; however, poor attention to basic application guidelines with traditional or hard-coat stucco can also lead to similar infiltration concerns.
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