Glass Types

Patent Glazing has proven to have an excellent safety record. However, it is important to ensure you specify the correct glass type in relation to the overall height of the glazing above the floor level. The following recommendations apply:-

Glazing Height above floor levelSuitable types for Single GlazingSuitable types for Double Glazing
Up to 5 MetresToughened, Laminated or Wired GlassThe inner pane must be Toughened or Laminated. The upper pane should be Toughened in either instance.
5 to 13 MetresToughened glass not more than 6mm thick and panes not larger than 3 sq/m.
Laminated or Wired Glass
The inner pane must be Toughened or Laminated. The upper pane should be Toughened in either instance.
Above 13 MetresLaminated or Wired GlassThe lower pane must be Laminated

From time to time, it is desirable to use Wired Glass in double glazed combinations. However, there is a high risk of breakage due to thermal stress and advice should be sort from the sealed unit manufacturer.

We do not recommend the use of Toughened Glass in single glazing or to the inner pane of double glazed units over swimming pools, food & beverage preparation units or any areas where the small broken pieces characteristic to this glass type, could cause subsequent injury due to contamination. In these situations laminated glass or

The most common types of glass suitable for over head glazing are detailed below. However, other infills can be accommodated including Polycarbonate, GRP & insulated panels:

Laminated Glass

Laminated glass consists of two sheets of glass bonded together with an interlayer. Commonly used are two sheets of annealed glass 3mm thick joined using a 0.4mm interlayer providing a finished pane 6.4mm thick. Alternatively, an interlayer 0.8mm thick is commonly available, offering a higher safety rating (see below). The glass is still breakable and is a little stronger than in its original form. However, the glass simply cracks and remains in place due to the bonded interlayer. This type of glass is also commonly used in the motor industry for car windscreens. Toughened glass may also be laminated to form a stronger pane when required. Laminated glass is currently the most commonly used type of single glazing for canopies, walkways, railway platform glazing and other unheated spaces. It is also suitable to use as the inner pane to double glazed units with Toughened on the outer pane.

6.4mm Laminated Glass obtains BS6206 Class B Safety Rating
6.8mm Laminated Glass obtains BS6206 Class A Safety Rating
ALL laminated glass with a PVB interlayer minimum 0.8mm thick obtains BS6206 Glass A Safety Rating

We do not recommend the use of Toughened Glass in single glazing or to the inner pane of double glazed units over swimming pools, food & beverage preparation units or any areas where the small broken pieces characteristic to this glass type, could cause subsequent injury due to contamination. In these situations laminated glass or polycarbonate are preferable.

Toughened Glass

Toughened safety glass is manufactured by heating common annealed glass to a temperature in excess of 600ºC causing it to soften. The surfaces of the glass cool quickly creating high compression resulting in up to five times increased strength. In the event of breakage, the pane shatters into relatively harmless small pieces of glass called ‘dice’. Whilst these dice may cause small cuts, it is unlikely serious injury will occur, so it is deemed to be ‘safety’ glass. It is important any cutting, polishing of edges or drilling be done before the process as once ‘toughened’ the glass cannot be worked on and is simply likely to shatter. Toughened glass is most suitable for the upper pane of double glazed units or in single glazing where the overall height above floor level does not exceed 5 metres.

All Toughened Glass has BS 6206 Clas A Safety Rating.

Wired Safety Glass

It is important not to confuse Wired Safety Glass with Wired Glass. The former has thicker wire which enables classification to BS6206 Class C Safety Rating, while the latter is now no longer suitable. Wired Glass has been used since the end of the 19th century for overhead glazing as the wires hold together any broken pieces of glass providing a similar, but not as efficient function as the PVB interlayer on Laminated Glass. Wired Safety Glass provides fire resistance, though care must be taken to ensure a suitable glazing system is also utilised to provide the required half hour or one hour protection.​