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 Sandwich panels and "quality" Components with a high level of prefabrication Sandwich panels are modern components with a very high level of prefabrication. The higher this level of prefabrication, the higher the manufacturer's obligation to prove the usability and quality features of these components. This documented evidence of conformity from recognised institutes/authorities facilitates the correct product selection for the building owner or planner. In addition to the static and building physics properties, quality features in respect of hygiene, cost effectiveness or durability must also be intensively highlighted. Quality-aware manufacturers of sandwich panels provide extensive verifications, certificates or documents.
Fig. 3.2.1 High demands of quality are particularly made on multifunctional components with a high level of prefabrication, such as sandwich panels for façade and roof. Recognisability of quality advantages Quality advantages go hand in hand with increased quality assurance measures by manufacturers. The necessary investments are absorbed in the pricing. Does this mean, however, that the principle "expensive = good" applies accordingly? No - because quality-aware suppliers of sandwich panels are also subject to the demands of the market and offset such investments with other potential savings. At least to some extent, because a complete compensation cannot absorb the enormous resources that must be used. Therefore, when using the modern generation of sandwich panels, planners and building owners must precisely assess and compare the requirements of the building with the properties of the building components. However, practice has shown that quality advantages are not always understood and accepted unanimously by the market. One of the most important reasons for this is evidently that planners and building owners do not always actually perceive the quality advantages of sandwich panels as quality advantages and do not recognise different qualities, and therefore - frequently to their disadvantage - turn to products with lower pricing. Quality inspection criteria With the modern generation of sandwich panels, an entire set of properties must be assessed, which influence not only the static and building physics functions but also the durability and cost effectiveness of the sandwich construction, and thus influence the entire structure. This laborious and time-consuming task is made considerably easier for planners and building owners by the manufacturers. They need only concentrate their attention on the presentation of verifications which, in combination, provide the greatest assurance. Which inspections are required? 1. Does the supplied sandwich panel have a General Building Supervisory Approval from the German Institute for Structural Engineering in Berlin, and does this have sufficient validity? The state building codes of the federal states of Germany generally require that anyone who puts building products into circulation must prove their usability. According to the law, sandwich panels are not regulated building products, since they are not based on technical rules such as, e.g. DIN standards. Therefore, sandwich panels require a General Building Supervisory Approval as proof of usability. The General Building Supervisory Approval clearly defines, among other things, the material properties and composition of the facings, the core insulation and the panel as the basis for the stability, usability, thermal insulation and fire behaviour. The approval should in all cases be valid beyond the planned completion period. However, with the restriction of defined properties, the installed product can also infringe further legal conditions as an immediate consequence. So, for example, in cold store and deep freeze construction or for cooling and deep freeze cells, hygiene requirements in accordance with the LMHV (Food Hygiene Ordinance) and the hygiene guidelines of the HACCP concept 1 take effect. If no tested quality characteristics exist in relation to hygiene, the operator or building owner of a cold store/deep freeze could be faced with a serious and expensive problem. 2. Do approval and product agree? The decisive question when using sandwich panels is, to what extent do the materials and material characteristics of the offered or supplied product agree with those in the approval. Ultimately, these values provide the basis for the static calculation, for the usability and for the required stability of the building.
1) HACCP = Hazard Analysis Critical Control Point
Fig. 3.2.2 Cover sheet of the General Building Supervisory Approval for a sandwich panel (reduced) 3. Does the sandwich panel have a mark of conformity? One of the most important tasks of the planner, building owner or installation company is to check that the supplied sandwich panels have a mark of conformity. Marking with the mark of conformity (Ü-Zeichen) is prescribed as compulsory by law in the ÜZVo (Mark of Conformity Ordinance), which is a constituent of all state building codes. The mark of conformity documents the approval-compliant manufacture of the sandwich panels in relation to the manufacturer’s internal permanent production control and regular external monitoring by a recognised independent institute. If all quality parameters required in the Building Supervisory Approval agree with the inspections, the external monitoring body issues the mark of conformity in the form of a certificate. The mark of conformity is thus the most important indicator of consistent, outstanding quality of the sandwich panels. In addition, the mark of conformity is a constituent of the product identification for each sandwich panel. This identification also includes the following additional obligatory data:
Fig. 3.2.3 The mark of conformity must be affixed to the packages or the delivery papers so that it is clearly visible
Fig. 3.2.4 Adhesive package label with mark of conformity and handling information
4. Additional assurance with RAL - GZ 617 quality assurance In addition to the static and building physics quality requirements, precisely defined requirements are also made on sandwich panels in respect of the product dimensions, geometry and dimensional accuracy. These were developed by the Gütegemeinschaft Bauelemente aus Stahlblech e.V. (Quality Association for Sheet Steel Structural Components) in the quality and inspection regulations for building components in steel sheet and published by the Deutsche Institut für Gütesicherung und Kennzeichnung e.V. (German Institute for Quality Assurance and Marking) as RAL - GZ 617. The dimensional stability of the facings, the dimensions of the sandwich panels and further requirements are precisely defined in these quality regulations.
Fig. 3.2.5 RAL - GZ 617 quality and inspection regulations
5. The GBS quality symbol guarantees the best quality - Can the manufacturer produce a quality symbol from the GBS - Quality Association for Sheet Steel Structural Components? Voluntary membership of the GBS is also an important criterion for the planner in determining how seriously the sandwich manufacturer takes the theme of “assured quality”. If these voluntary quality requirements and conditions of the GBS are observed by the member, then the sandwich panel manufacturer obtains the GBS quality symbol. If this quality symbol is withdrawn from a manufacturer, the building owner or planner can be sure that serious quality problems or even violations of legal building regulations exist.
Fig. 3.2.6 GBS quality symbol (RAL) The planner’s duty of care requires up-to-date information The planner’s duty of care requires that the planner’s information is always up-to-date. Both GALILEO - Creative Sandwich Construction and the IFBS - Industrieverband für Bausysteme in Stahlleichtbau e.V. (Industrial Association for Light-Gauge Steel Construction Systems) provide planners, building owners and successful tenderers with excellent and constantly updated information about sandwich construction. As the final quality of a building is defined not only by the product quality, but to a great extent also by the planning and execution quality, regular access to this information is very useful. Fig. 3.2.7 GALILEO - Creative Sandwich Construction website: www.sandwichbau.com
Fig. 3.2.8 IFBS website: www.ifbs.de Few black sheep with regard to quality Finally, we will deal with the “black sheep”. Unfortunately they also exist among sandwich manufacturers, although happily they are very few in number. Expressed in figures: of the around 50 sandwich manufacturers in Europe, who are listed in the “Sandwich Construction” reference book as “Quality-oriented manufacturers”, a total of four manufacturers stood out, two of whom crop up particularly frequently. Through regular controls and inspections of product samples on buildings, GBS and IFBS have gained an overview of these companies and their products, some of which have been used without General Building Supervisory Approval, without mark of conformity or without the necessary fire protection. In the period between July 2002 and July 2003, GBS / IFBS recorded a total of eight such building regulation violations. In the case of two of the buildings, the sandwich panels used had no General Building Supervisory Approvals. In the other six cases, inspections showed that the core insulation was easily flammable, i.e. B3, in violation of the legal building regulations in Germany. In this connection, it is also good that GBS and IFBS rigorously pursue such cases, and inform the relevant districts and building authorities. This is another good reason why planners should take a stronger interest in the “assured quality” of the building components used and, particularly in the case of obvious price cutting, demand the quality certificates specified here from the manufacturer or supplier, and check these in detail. Author
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