In the United States the International Building Code and ASTM International define Exterior Insulation and Finish System (EIFS) as a nonload bearing, exterior wall cladding system that consists of an insulation board attached either adhesively or mechanically, or both, to the substrate; an integrally reinforced base coat; and a textured protective finish coat.
EIFS with Drainage, another EIFS system, is the predominate method of EIFS applied today. As the name implies, EIFS with Drainage provides a way for moisture that may accumulate in the wall cavity to evacuate.
Although often called “synthetic stucco”, EIFS is not stucco. Traditional stucco is a centuries-old material which consists of aggregate, a binder, and water, and is a hard, dense, thick, non-insulating material. EIFS is a lightweight synthetic wall cladding that includes foam plastic insulation and thin synthetic coatings. There are also specialty stuccos that use synthetic materials but no insulation, and these are also not EIFS. A common example is what is called one-coat stucco, which is a thick, synthetic stucco applied in a single layer (traditional stucco is applied in 3 layers).
EIFS are proprietary systems of a particular EIFS manufacturer and consist of specific components. EIFS are not generic products made from common separate materials. To function properly, EIFS needs to be architecturally designed and installed as a system. The materials and installation methods specified by different EIFS manufacturers are not all compatible and should not be used interchangeably in new construction or repair work.
The technical definition of an EIFS does not include wall framing, sheathing, flashings, caulking, water barriers, windows, doors, and other wall components. However, some architects have begun specifying flashings, sealants, and wiring fasteners as being a part of the EIFS scope of work, essentially requiring EIFS contractors to carry out that work as well. The technical national consensus standard for the definition of an EIFS, as published by ASTM International does not include flashing or sealants as part of the EIFS. Many of the EIFS manufacturers have their own standard details showing typical building conditions for window and door flashings, control joints, inside/outside corners, penetrations, and joints at dissimilar materials which should be followed for that manufacturers warranty.