EIFS Classification Paper: 1980 and 1990s
Editor’s note: This paper is written and distributed by EIMA and presented here in unedited form.
The EIFS Industry Members Association (EIMA) is a nonprofit trade association representing member firms engaged in the manufacture of exterior insulation and finish systems (EIFS), suppliers of components of these systems, distributors of systems, applicator/contractors who install EIFS, and related building industry professionals. EIMA offers the following definition of EIFS.
Description
EIFS are non load bearing, barrier wall, exterior cladding systems generally consisting of the following components:
- Insulation board.
- An adhesive and/or mechanical attachment of the insulation board to a substrate.
- Glass fiber reinforcing mesh.
- Base coat on the face of the insulation board that functions as the weather barrier.
- A textured protective finish coat.
EIFS components function collectively to provide weather protection, durability, and aesthetic versatility. EIFS manufactured by EIMA members meet industry performance standards and are recognized by major model building codes. For single source responsibility, and to ensure component compatibility, it is strongly recommended that designers specify EIFS furnished by a single source EIMA member. EIMA has classified EIFS as Class PB of Class PM systems.
Class PB Systems
The base coat thickness varies depending upon the number of layers or thickness of reinforcing mesh. The reinforcing mesh is embedded into the base coat per EIFS manufacturer recommendations and with no mesh color visible.
Protective finish coats, of various thickness, in a variety of textures and colors, are applied over the base coat.
Class PM Systems
- The base coat is applied to a uniform thickness which can range from a nominal 1/4-in. (6 mm) to 3/8-in. (9 mm). The base coat thickness is not dependent upon the number of layers or thickness of reinforcing mesh. The reinforcing mesh is installed over the surface of the insulation board. The base coat is applied over the reinforcing mesh.
- Protective finish coats, of various thickness, in a variety of textures and colors, are applied over the base coat.
The components of each manufacturer’s proprietary Class PB and Class PM systems may vary.
EIMA publishes guideline specifications for both Class PB and Class PM systems and other technical documents. Contact EIMA for a complete listing of publications.
As previously discussed, in 1995 moisture intrusion issues were identified in EIFS clad homes. This led to the development of EIFS with drainage often referred to as Moisture Drainage – Exterior Insulation and Finish System (MD-EIFS) in the late 1990s. Related to this, were revisions to the Acceptance Criteria for Exterior Insulation and finish Systems with the first interim AC 24 issued April 1997.
EIFS Classification Paper: 2000s to today
EIMA now provides the following definition of EIFS:
According to the definitions contained in the International Building Code and ASTM International, an Exterior Insulation and Finish System (EIFS) is a non-load 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 typically consist of the following components:
- A water-resistive barrier (WRB) that covers the substrate.
- The drainage plane between the WRB and the insulation board and is most commonly achieved with vertical ribbons of adhesive applied over the WRB.
- Insulation board typically made from expanded polystyrene (EPS) but can also be XPS or polyisocyanurate.
- An insulation board is attached with an adhesive or mechanically to the substrate.
- Glass-fiber reinforcing mesh embedded in the base coat.
- A water-resistant base coat that is applied on top of the insulation to serve as a weather barrier.
- A finish coat that typically uses colorfast and crack-resistant acrylic co-polymer technology.
EDI Note: MD-EIFS must also have a drainage method provided at the bottom of walls to let moisture at the WRB drain from the wall system. A clarification to the second bullet above where the paper states “… most commonly achieved with vertical ribbons of adhesive applied over the WRB; this WRB must be a liquid applied WRB.