Stucco and EIFS are common cladding systems that appear similar from the exterior. these systems have very different attributes however. This digest explains the reasons why face-sealed EIFS are fundamentally flawed as cladding systems for most applications, and describes how drained EIFS can be used successfully in almost all climate zones and exposures. Cracks, lamina deterioration, and movement joints are also discussed.
EIFS AND STUCCO:
EIFS (Exterior Insulation and Finish Systems) are cladding systems that combine a finish with a layer of exterior insulation. The finish is comprised of polymeric (organic) bonded aggregate and cement reinforced with a glass mesh. Stucco is a cladding made of inorganic-cement (Portland Cement and/or Lime) bonded sand or earth used for thousands of years. Although these two claddings may look the same, they perform very differently.
EIFS became very popular in the 1980's and experienced a significant number of serious failures, almost all related to rain penetration. Early EIFS used a face-sealed approach (defined later). Face-sealed exterior insulation and finishing systems (EIFS) are inherently defective and unfit for use as an exterior cladding system where moisture sensitive componenets are used without a provision for drainage or in locations and assemblies without adequate drying. Most EIFS of the past were face-sealed systems that by definition had no provision for drainage. The typical system also contains moisture sensitive materials. Specifically, the following moisture sensitive componenets are used: exterior gypsum boars, oriented strand board (OSB) or plywood sheathing, metal or wood studs, fiberglass cavity insulation and interior gypsum boars sheathing.
Drained EIFS are significantly different from face-sealed systems in that, by definition, they have a provision for drainage. unlike face-sealed perfect barrier systems such systems can be successfully used as an exterior cladding system in essentially all climates and exposures. Drainable EIFS are not subject to the same limitations of uses as face-sealed or barrier systems. In fact, drainable EIFS are among the most robust and advanced moisture contrl assemblies available.