The Problem with EIFS (Synthetic Stucco)

In every case, water intrusion is attributable to one or more of the following situations:

No caulking around windows, doors or other penetration points.

Faulty caulking at penetration points or correct caulking which is not applied according to the EIFS manufacturer or sealant manufacturer's specifications.

No flashing or improper flashing at rooflines, heads of penetrations, deck-to-house attachments and other joints.

Windows which leak and fail to meet building code specifications.

Foam board installation where foam panels are not installed according to manufacturers directions.

Synthetic stucco is basically a type of foam sheeting glued and nailed to the structural sheathing (usually plywood) on the exterior of a home. This material has a either factory or field applied fiberglass mesh installed over the outer surface which is then finished with two or more coats of the stucco-like material.

When properly installed, the system in generally waterproof, and there lies the problem. The coating is not only waterproof on the outside but on the inside as well. If any water gets behind the coating through some kind of breach, it cannot easily get out.

In response to numerous complaints about moisture trapped inside of exterior walls, building officials in Wilmington, North Carolina, implemented a large-scale study of hundreds of homes clad in synthetic stucco. They found a significant number of these houses indeed had problems with moisture in wall cavities which were contributing to decay of structural lumber.

The Wilmington study and the independent observations of home inspectors found that builders frequently installed the material incorrectly or homeowners failed to maintain it properly. The most common source for water entry is at joints between sections of the material and dissimilar materials, improperly sealed bottom edges, window and door flashings, poor caulking and gaps around decorative trim.

Water intrusion can lead to swelling, loosening and buckling of the foam substrate and cracks and general deterioration of the foam and coating. Continued moisture trapped inside of walls can lead to water stains on interior walls and the eventual decay and failure of structural lumber in areas surrounding leakage.

Another source of concern is the ability of an EIFS clad home or building "to breath". Interior humidity can become trapped within the wall cavities and accumulate inordinately high moisture concentration which promotes dryrot in the wood sheeting and structural framing.

Due to the incubation nature of trapped moisture, damage can occur at an accelerated rate. Owners of an EIFS (Synthetic Stucco) clad house or building should have it inspected for possible points for water entry and high moisture content in the wall sheeting and cavities. If no problem currently exists, annual follow up inspections are recommended for monitoring purposes. On the other hand, if high moisture concentrations exist, immediate repairs are indicated. If problems are widespread, entire removal of the EIFS (Synthetic Stucco) cladding system may be indicated.