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ETICS_____________________________________________________ | |
| Author: | Wegelin, Hans |
| In: | Architecture South Africa July/Aug |
| Date: | 2015 |
| Pages: | 65-66 |
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External wall insulation systems started off in Germany in the 1960's as a popular method of improving thermal performance of existing masonry or concrete building stock. It consisted of polystyrene insulation panels glued or mechanically fixed to the external wall surface and finished with a thin reinforced synthetic resin plaster. Nowadays known as External Thermal Insulation Composite Systems1 (ETICS), it has a satisfactory track record in Europe and proves to be as durable as conventional masonry and plaster systems. Millions of square metres are installed every year, including on new framed buildings where the system is fixed on continuous sheathing. In the mid-1990's in the USA and Canada, where the system is known as EIFS (External Insulation and Finish System), damage cases were reported on wooden stud-and-sheath buildings in cold regions with high precipitation intensities, leading to rotting wood, international controversy and numerous lawsuits. Culprits were pointed out as inadequate detailing of joints and openings, and the drying potential of the wall. But today ETICS generally provides excellent moisture protection at the outer plane of the wall. Liquid-applied waterproof barriers have been developed to be applied directly to the sheathing, to which adhesives are applied with a U-notched trowel in order to create vertical drainage channels between the ribbons. Etics is now considered the superior thermal and moisture barrier in any climate. ETICS as a new concept in South Africa seems to be taking off and should do well in our mainly dry and forgiving climate. If workmanship on framed walls is shoddy and water is allowed into the cavity we might have to deal with 'reverse' condensation - typical of a warm climate - of warm moist air condensing on the external face of internal cladding adjacent to cool air-conditioned spaces. ETICS is normally a proprietary system that needs to be architecturally designed and installed as a system. Finishes can be expanded to any kind of plaster, brick slips or tiles. Endless design possibilities may be achieved by adding computer modeled polystyrene forms. ETICS are pre-manufactured and are quickly erected, saving construction time. ETICS, due to its relative soft surface, is best avoided in spaces where vandalism is a problem. This building2 is one of many recent examples of steel-framed insulated cavity walls3 in Pretoria. The light steel structural frame supports two layers of gypsum board internal cladding, and external sheathing of 0,58 mm galvanised steel sheet, followed by a vapour membrane with taped overlap joints, followed by two layers of high-density EPS, a thin polymeric base coat reinforced with fibreglass mesh, and a red-coloured finishing coat. EPS panel salient angles are reinforced with corner beads. Note that there is no need for insulation in the frame cavity. Insulation panels are fixed to the frame with metal pins in plastic sleeves to minimise metal-to-metal contact to the frame, reducing thermal bridging. Sources: Kiinzel H, SedlbauerK. 2006. Long-term performance of external thermal insulation systems (ETICS). Fraunhofer-lnstitute for Building Physics, Holzkirchen, Germany. Wikipedia. ______________________________
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