Like any other building product, natural stone requires some controls to ensure its quality. The checks to be performed on stone products should be done in phases of manufacturing, supplying and reception at work and are, on the one hand, product liability and, secondly, responsibility of the Project Manager.
CE marking Since 2003, manufacturers of natural stone products are required to perform some checks on their production, related to CE marking, mandatory requirement for marketing in the European Union. For this reason, producers should implement a factory production control (FPC), consisting in laboratory tests with some frequency, to know the physical-mechanical properties of the material and, secondly, to control production dimensionally and visually. All this according to the European standards EN apply to each product. After implementing this monitoring process, the manufacturer produces two documents: a Declaration of Performance (DoP) and a CE marking, which is affixed on the product.
After implementing this monitoring process, the manufacturer produces two documents: a Declaration of Performance (DoP) and a CE marking, which is affixed on the product.
Controls prior to delivery of stone
Natural stone's heterogeneity is sometimes a matter of dispute between the contractor and the supplier as the expected look is not obtained once the work is complete. This is because the natural stone usually has variations of colour, texture, marbled, etc., associated with its natural origin and need not constitute grounds for rejection.
Many designers look to enhance the aesthetic value of the pavement from the variations in appearance. In general, it could be said that the variations in appearance along with a sufficiently harmonious laying can be a tool of architectural design rather than a cause of rejection.
Therefore it is necessary that, before delivery of the material, the manufacturer provides a reference sample consisting of at least four pieces and covering an area of at least 0,36 m2. The said sample must represent the material's extreme and average aspects and must be accepted by agreement between the supplier, the project management, and the property owner. The criteria for acceptance or rejection of certain defects must be defined contractually between the manufacturer and the client before the supply starts.