The weather barrier must be properly flashed and coordinated with all other portions of the exterior wall to prevent water from migrating into the underlying walls or interiors.

Wall drainage EIFS systems are similar to cavity walls they are installed over a weather barrier behind the insulation that acts as a secondary drainage plane. Therefore, all other components of the exterior wall must either be barrier type systems or be properly sealed and flashed to prevent water from migrating behind the EIFS and into the underlying walls or interiors. Barrier EIFS wall systems rely primarily on the base coat portion of the exterior skin to resist water penetration. The insulation typically consists of extruded expanded polystyrene (XPS) and is mechanically attached to the sheathing and or wall structure.ĮIFS is available in two basic types: a barrier wall system or a wall drainage system. This system has a nominally 3/16 inch to 1/2 inch thick reinforced base coat applied to the insulation prior to application of the finish coat. The second and less common type of EIFS is the polymer modified (PM) system. The insulation typically consists of closed expanded polystyrene (EPS) and can be either adhesively or mechanically attached to the sheathing. This system has a nominally 1/16 inch thick reinforced base coat applied to the insulation prior to application of the finish coat.

The most common type of EIFS is the polymer based (PB) system. Over the years, variations of this system have been developed. The Dryvit system consisted of expanded polystyrene (bead board) attached adhesively to the sheathing and covered with a lamina composed of a modified cement base coat with woven glass fiber reinforcement and a textured colored finish coat. EIFS in its current basic form was developed in West Germany in the 1960s and introduced in the United States in 1969 by Dryvit. Exterior Insulation and Finish System (EIFS) is an exterior wall cladding that utilizes rigid insulation boards on the exterior of the wall sheathing with a plaster appearance exterior skin.

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