Determining the thickness of glass

The thickness of glass for a given application is determined by a number of factors:

the dimensions of the pane
the orientation (vertical, inclined, horizontal)
the way it is supported (number of supported edges)
the loads applied (wind load, snow load, point loads, barrier loads)
the function of the glazing (safety, security, fire-resistance)
the maximum permissible deflection.

Wind loading

Wind loads are calculated in accordance with BS EN 1991-1-4 and the relevant national annex. The wind load on a building depends on the geographic location, the topography, the height of the building, the orientation of the facade and the size and shape of the pane.

Calculation method

Once the design wind pressure has been established, the thickness of the glass can be determined using tables and graphs based on the panel size, support conditions and required safety factors. For large panes, complex shapes, or high-risk applications, finite element analysis may be required.

Notes

For inclined or overhead glazing, additional loads from the weight of the glass itself, snow and maintenance access must be considered.
For barrier glazing, additional point loads and line loads representing impact and crowd loading must be considered.
Toughened or laminated glass may be required for safety reasons in many locations, regardless of strength calculations.