Glazing in critical locations
For all buildings
5.2 In critical locations, comply with one of the following.
a. Ensure that glazing, if it breaks, will break safely (see paragraphs 5.3 and 5.4).
b. Choose glazing that is one of the following:
(i) robust (see paragraph 5.5)
(ii) in small panes (see paragraphs 5.6 and 5.7).
c. Permanently protect glazing (see paragraph 5.8).
5.3 Safe breakage is defined in BS EN 12600 section 4 and BS 6206 clause 5.3. In an impact test, a breakage is safe if it creates one of the following.
a. A small clear opening only, with detached particles no larger than the specified maximum size.
b. Disintegration, with small detached particles.
c. Broken glazing in separate pieces that are not sharp or pointed.
5.4 A glazing material would be suitable for a critical location if it complies with one of the following.
a. It satisfies the requirements of Class 3 of BS EN 12600 or Class C of BS 6206.
b. It is installed in a door or in a door side panel and has a pane width exceeding 900mm and it satisfies the requirements of Class 2 of BS EN 12600 or Class B of BS 6206.
5.5 Some glazing materials such as annealed glass gain strength through thickness; others such as polycarbonates or glass blocks are inherently strong.
The maximum dimensions for annealed glass of different thicknesses for use in large areas forming fronts to shops, showrooms, offices, factories and public buildings with four edges supported are shown in Diagram 5.2 (see also paragraph 7.1).
Glazing in small panes
5.6 In the context of this approved document, a ‘small pane’ is an isolated pane or one of a number of panes held in glazing bars, traditional leaded lights or copper lights (see Diagram 5.3).
5.7 Small panes should be provided in accordance with all of the following.
a. In a small annealed glass pane, use glass with a minimum 6mm nominal thickness except in the situation described in b.
b. In traditional leaded or copper lights, when fire resistance is not important, you may use 4mm glass.
c. Use the dimensions and areas shown in Diagram 5.3.
Permanent screen protection
5.8 If glazing in a critical location is protected by a permanent screen then the glazing itself does not need to comply with requirement K4.
The permanent screen should comply with all of the following.
a. Prevent a sphere of 75mm from coming into contact with the glazing.
b. Be robust.
c. If it protects glazing installed to help prevent people from falling, be difficult to climb (e.g. no horizontal rails).
See Diagram 5.4.