Document N – Building Regulations - Protection against impact

From 1 June 1992 it will be a legal requirement to ensure that glazing complies with the minimum standards set.  This applies to the installation of all glazing.

Critical Locations

1.1 The following locations may be considered ‘critical’ in terms of safety;

a. between finished floor level and 800mm above that level in internal and external walls and partitions (see Diagram 1).

b. between finished floor level and 1500mm above that level in a door or in a side panel, close to either edge of the door (see Diagram 1).

Safe Breakage

In terms of safe breakage, a glazing material suitable for installation in a critical location would satisfy the requirements of Class C of BS 6206 or, if it is installed in a door or in a door side panel and has a pane width exceeding 900mm, the requirements of Class B of the same standard.

Robustness

1.4 Some glazing materials, such as annealed glass, gain strength through thickness; others such as polycarbonates or glass blocks are inherently strong. Some annealed glass is considered suitable for use in large areas forming fronts to shops, showrooms, offices, factories, and public buildings. Reasonable glass thickness/dimension limits for annealed glass which may be used in these locations are shown in Diagram 2 above.

Glazing in small panes

1.5 In the context of this Approved Document, a small pane’ may be an isolated pane, or one of a number of panes contained within glazing bars, traditional leaded lights or copper-lights.

1.6 Small panes should have a smaller dimension not exceeding 250mm and an area not exceeding 0.5m each measured between glazing beads or similar fixings. Annealed glass in a small pane should not be less than 6mm nominal thick, except in traditional leaded or copper-lights in which 4mm glass would be acceptable, when fire resistance was riot a factor.  Typical installations are shown in Diagram 3.

Permanent screen protection

1.7 If, as part of a design solution, glazing in a critical location is installed behind permanent screen protection, the screen should:

a. prevent a sphere of 75mm from coming into contact with the glazing,

b. be robust and,

c. if it is intended to protect glazing that forms part of protection from falling, be difficult to climb.

1.8 Glazing in a critical location which is afforded permanent screen protection, does not, itself, need to comply with requirement Ni. The principles of screen protection are shown in Diagram 4.