Determination of glass thickness in facades and roofs, in traditional methods

This article sets out the rules for calculating the thickness of glazing used in building structures.

These rules define, on the one hand, the loads to be taken into account and, on the other, the criteria to be met depending on the technique used.

Since, on the one hand, the mechanical performance of glazing depends on the nature of its basic components and the way in which these components are combined in the final glazing, and, on the other hand, the load resulting from the glazing's own weight cannot be known at the time of calculation, since the purpose of the calculation is precisely to define the thickness of each of the glass panes making it up, The principle of the calculation is to determine the minimum necessary and sufficient thickness of an annealed monolithic glass that meets the loads applied to it, and then to check that the composition we have chosen, a priori, meets the minimum thickness obtained by calculation and the deflection criterion that applies to the structure in which the glazing is installed.

In this article, we'll look at glazing installed in frames with glazing beads that meet the requirements of DTU n° 39 , or when they form a tempered glass unit. In a second article, we'll look at glazing installed by bonding to a support (VEC – vitrage extérieur collé), or fixed to a structure (VEA – vitrage extérieur attaché).

First, we'll look at the loads exerted on glazing depending on how it's installed, then we'll give the calculation formulas used to define its thickness.

Calculation examples are given to illustrate how to arrive at the correct glazing composition.