ETICS’ pathologies

The use of the ETICS is covered by a specific indication of legislation: the ETAG 004 Guideline for Technical Approval of External Thermal Insulation – Composite Systems With Rendering, issued by EOTA European Organization for Technical Approvals; so all applications should include approved systems, with the ETA European Technical Approval marking, which raised from an Approval Body. From the design point of view, ETICS are differentiated according to the methods of fixing: bonded ETICS, bonded ETICS with supplementary mechanical fixings, mechanically fixed ETICS with supplementary adhesive, purely mechanically fixed ETICS. There are also different types of substrates (masonry walls [made from units of clay, concrete, calcium silicate, autoclaved aerated concrete or stone]; in situ or prefabricated concrete walls; wood structures. ETICS components are many and can be very different from one system to one other: basically are adhesive (dry mortar, powder requiring addition of extra binder, paste requiring addition of cement, ready-to-use paste), with more of less organic resin; insulation product (basically EPS, mineral wool, and wood wool, but also cork, XPS, PU); rendering system, made by reinforcement (glass fiber, or plastic mesh - standard or reinforced -, or metal lath, or dispersed fibers embedded or dispersed in render coating, formed by base coat, key coat; finishing coat and decorative/protective coat; mechanical fixing devices and ancillary materials and components, as window’s sills, corners, joint-covers, sealants, mastics and so on. Due to the complexity of the structure and number of performance required, in the case of emerging pathologies the checking for causes is very difficult. The paper shows a method for doing this, based on: the study of the influence of local conditions; the respected or not, from every layer and from the relationship between the layers, of the performances fixed by ETAG 004 and by other Specialized Body, as Groupe Spécialisé n°7 of C.S.T.B.; or extracted by case studies observed by the authors or known in the literature.