Exterior insulation and finishing system (EIFS) is a type of building exterior wall cladding system that provides exterior walls with an insulated finished surface and waterproofing in an integrated composite material system.
EIFS consists of a number of layers that are installed in the following order. The most basic EIFS (a barrier EIFS) consists of 3 layers:
- A layer of foam plastic insulation (also called simply "foam") that comes in the form of sheets 2' x 4'. If an adhesive is used to attach the insulation, the adhesive is applied to the foam with a trowel. Most EIFS use a type of insulation called Expanded Polystyrene, also known as EPS. EPS is 1 lb. density Expanded Polystyrene, similar to the white foam that coffee cups are made of. The usual range of thickness for EIFS insulation is 3/4" to 4", although thicker pieces are sometimes used for decoration accents – called foam shapes.
- A reinforced layer that is applied onto the face of the insulation with a trowel, consisting of a fiberglass reinforcing mesh ( or "mesh") embedded in a cementitous adhesive. The mesh has an open weave, somewhat like window screening but with opening about 1/4" square. It is made of fiberglass and can be cut with a utility knife. The mesh is available in various weights, the "heaviness" determines the impact strength of the surface (resistance to damage by being "hit"). The standard weight is 4oz, the high-impact mesh weight goes up to 15 or 20oz. This 2-part layer is called the Base Coat.
- A final topcoat,or finish, which is a colored, textured paint-like material that is applied with a trowel or, very rarely, by spraying. A wide range of colors and textures are available as well as custom colors. Available textures include smooth surfaces, rough "stucco-like" textures, embedded stone chips, multi-color (granite-like mixtures,) and even brick-like treatments. This layer is called the finish. It is acquired by floating.