Glass pathologies in the building industry

Building professionals (architects, contractors, glaziers, etc.) and homeowners are frequently confronted with problems involving visible defects in glazing. The origin and explanation of these irregularities are not always obvious. They may be the result of simple physical, optical or chemical phenomena, inherent in the glass itself or in the processing of glass products.

The quality of a glazing's appearance is determined by the analysis of defects likely to cause discomfort, impair vision or lead to optical distortion.

For a long time, there were no French or European standards governing the acceptable level of these defects. Recently, a number of European standards have addressed this issue, but without fully meeting the demand from professionals to settle any disputes that may arise.

In 1997, the Fédération Française des Produits Verriers (FFPV) drew up a document entitled Règles professionnelles pour le vitrage isolant (Professional rules for insulating glass units), to define a number of basic rules for manufacturers and users of insulating glass units. These rules are designed to enable an observer looking outwards from the inside to assess the visual quality of insulating glass units in daylight at the time of delivery. However, these criteria only apply to insulating glass units rebated around their edges.

The aim of this article is to provide information to help identify the origin of these defects.