What is Exterior Insulation Finishing System (EIFS)?

EIFS or Exterior Insulation Finishing System is an external cladding system used to provide insulation, finishing and waterproofing to the building exterior. EIFS is a synthetic wall cladding that is usually have a plastic insulation, foam and a synthetic coating. EIFS are usually placed on the building exterior, using a adhesive agent attached to gypsum board.

Fig. What is Exterior Insulation Finishing System (EIFS)?
Lets look into the important features of EIFS and its construction details.

Features of EIFS in Building Construction

  1. EIFS are non-bearing building cladding systems provided at the exterior.
  2. EIFS provide insulation, water-resistance and a finished surface
  3. EIFS are a composite material system
  4. EIFS are also called as External Wall Insulation System (EIWS) and External Thermal Insulation Cladding System (ETICS) in Europe
  5. EIFS is a lightweight synthetic wall cladding
  6. EIFS include foam plastic insulation and synthetic coating.
  7. EIFS are not generic products that are made from common separate materials. They are architecturally designed and installed as a system as per the requirements.
  8. This is a product that is manufacture dependent. All EIFS manufacturers are not compatible and must not be used interchangeably

Installation of EIFS

  1. The EIFS units are attached to the outside face of the exterior walls using an adhesive or mechanical fasteners.
  2. The adhesive used for the purpose can be either, cementitious or acrylic based
  3. Usually, these adhesive agents are used to attach the EIFS units onto a gypsum board, cement board or concrete substrates.
  4. Mechanical fasteners are used when EIFS are installed over housewraps. 
  5. The supporting structure should be continuous without any open framing and be flat.

Classification of EIFS 

EIFS are mainly classified into two types based on the material used and the availability of a drainage system. Hence, there are:
  1. Class PB
  2. Class PM

1. Class PB EIFS

This is the polymer based EIFS system that are commonly used in North America. It uses expanded polystyrene (EPS) insulation adhered to the substrate with fiberglass mesh embedded in a nominal 1.6mm base coat. This can receive additional layers of mesh and base coat to increase the impact resistance. A polyisocyanurate insulation board can also be used.

Fig. Class PB EIFS - Using Expanded Polystyrene
Image Credits: PALADIN

2. Class PM EIFS

This is polymer modified EIFS that uses extruded polystyrene insulation (XEPS) along with a cementitious base coat applied over mechanically attached glass fiber reinforcing mesh. PM EIFS make use of different insulation materials and base coats based on the requirements.

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