EIFS claddings are a rigid insulation board that is usually manufactured in different sheet sizes and thicknesses from expanded polystyrene with a plaster and paint finish. These cladding systems also provide some insulation value.
Most EIFS claddings are proprietary systems that consist of a fibreglass-reinforced base coat and jointing system applied over the installed sheets, together with textured polymer or acrylic weathertight finish coats. They also incorporate specific installation components such as window penetration flashings, which are generally manufactured from UPVC, and these are fundamental to the weathertight performance of the system.
EIFS claddings are used to create a monolithic finish on a building. The weathertight exterior coating creates a weatherskin and a face seal to the cladding that is very airtight. Uncoated sheet edges can be very absorbent, and they may wick water from adjacent surfaces such as waterproof decks and roofs. All exposed sheet edges must be well coated.
Expansion or movement control joints must always be incorporated in the finished cladding in strict accordance with the manufacturer’s requirements.
Direct-fixed EIFS claddings are not considered to be very robust once water has penetrated the face seal and are not covered under E2/AS1. When installed on a drained and vented cavity, they offer significantly more potential for drainage and air circulation and are therefore more robust.
The weathertight performance of these systems is very dependent upon accurate installation, and EIFS should always be installed by a manufacturer-approved specialist installer.
Check the manufacturer’s specification regarding installation requirements for weathertightness risk. EIFS must be installed over a nominal 20 mm cavity when using E2/AS1 as a means of compliance.
Owners should also be made aware that these systems are very high maintenance and that the face seal coating system must be well maintained. Any faults in the cladding must be repaired immediately as they are intolerant of moisture penetration.
EIFS claddings are vulnerable to:
- thermal movement
- building movement
- poor installation (there are a number of high-skill processes involved in jointing and coating and in the installation of penetration flashings)
- joint cracking (followed by moisture absorption)
- poor surface coating application
- moisture absorption at poorly coated sheet edges
- lack of maintenance.
Updated: 9 September 2014