Risk Management Guidelines

Transcription

1 Glazing Materials Introduction This note offers advice on the selection of glazing materials for use in doors and other high risk areas. Statutory Requirements and Standards Requirements as to glazing selection and construction are contained in various pieces of legislation and British Standards. The main items are: - 1. The Building Regulations Approved Document N - Glazing Materials and Protection. These came into operation on the 1st June 1992 and apply to all new buildings and building modifications but not to simple replacement of existing panes. Similar provisions apply for Scotland. 2. Workplace (Health, Safety and Welfare) Regulations 1992 which apply to all places of work. The basic provisions of the above Regulations are similar in that:- 1) Glazing with which people are likely to come into contact while in passage in or about the building shall: a) if broken, on impact, break in a way which is unlikely to cause injury, or b) resist impact without breaking, or c) be shielded or protected from impact. d) transparent glazing, with which people are likely to collide while in passage in or about the building, shall incorporate features so as to make it apparent. 3. BS6262-4: Glazing for buildings. Safety related to human impact 4. BS 6206: which details the test parameters for safety glass. 5. BS 6180: on barriers and balustrades. Glass Construction and Fracture Characteristics Annealed Glass Commonly known as float glass, sheet glass, patterned glass or tinted float glass. This is manufactured by a variety of techniques whereby glass is cast onto a flat surface and then allowed to cool slowly in annealing ovens. If annealed glass breaks and is penetrated any pieces dislodged will be sharp. Wired Glass Wired glass is some form of annealed glass with a mesh of wire incorporated. If broken under impact the pieces are held together by the wires and penetration is unlikely. If penetrated the edges are similar to annealed glass Royal & Sun Alliance Insurance plc

2 Toughened (Tempered Glass) This is glass that is rapidly cooled from the melt such that the outer skin is under a condition of compressive stress. This makes the material strong but if broken it will fragment into relatively harmless small pieces. areas where there are added risks to children, whose more active behaviour may lead to more frequent accidents. vulnerable situations, for example landings, balconies, stairways and at the bottom of stairs. Laminated Glass Critical locations have been identified as: This is manufactured by welding sheets of annealed glass together using a plastic film or bond. Fracture characteristics are similar to annealed glass but the pieces will remain substantially adhering to the plastic interlayer. Laminated glass is difficult to penetrate. doors and side panels that may be mistaken for doors, up to a height of 1500mm above floor level. glass or plastics wholly or partially within 800mm from floor level, in windows, internal walls and partitions. Plastic Covered Annealed Glass This is annealed glass that has been coated with a film or covered with a specially formulated organic material intended to hold the glass together after breakage. When broken this material is difficult to penetrate providing the coating is applied in accordance with the manufacturers recommendations. Hazard Areas It is difficult to be categorical about what is a critical area and consideration needs to be given to the design of the building, expected use and the foreseeability of accidental human impact. Such areas include: corridors and assembly areas where the glazing is not protected by a protective rail or by being recessed. Reducing the Risks Glazing in critical locations should: - break safely, if it breaks, or be robust or in small panes, or be permanently protected. Selection of Glazing Material Detailed criteria can be found in BS 6262 or Approved Document N and of particular reference are Tables 1 and 2 (attached) which give reasonable glass thickness/area limits for annealed glass in critical locations. Table 2 is drawn from the original BS 6262 and may be relevant in existing buildings. Table 1 is taken from Approved Document N and the Workplace (Health, Safety and Welfare) Regulations Approved Code of Practice Royal & Sun Alliance Insurance plc

3 In general terms: - New Buildings [Document N] Frameless doors and side panels should be safety glass. Fully glazed doors and side panels should be safety glass or annealed glass complying with Table 1, except that small panes not exceeding 250mm width and 0.5m 2 area may be annealed glass of not less than 6mm nominal thickness. Internal partitions, windows, etc, within 800mm of the floor to be safety glass or annealed glass (Table 1). Existing Situations [BS 6262] Frameless doors/side panels to be safety glass. Fully framed doors/side panels with a single pane to be safety glass, unless the pane is less than 300mm wide when glass may be in accordance with Table 2, subject to a minimum thickness of 6mm unless area is less than 0.02m 2 when 4mm glass may be used. Fully framed doors and side panels with more than one pane should comply with Table 2, subject to a minimum thickness of 6mm. Windows/internal panels within 800mm of the floor are to be safety glass (in areas where people are likely to be gathering or passing), or otherwise subject to Table 2. Protection Systems As an alternative to safety glass, glass in critical locations may be protected. Under the Building Regulations the requirements are that the screen should: - prevent a sphere of 75mm from coming into contact with the glazing be robust and, if it is intended to protect glazing that forms part of protection from falling, be difficult to climb. Under BS 6262 glass in critical locations normally expected to be safety glass was allowed to comply with Table 2 if protected by a system satisfying the following criteria: - The overall face width should be 75mm minimum. If 900mm or over in length the protective system should be suitably robust to prevent fracturing, deflection, permanent distortion or displacement. If vertical the protective system should be towards the centre of the glazing area or, if horizontal, be between 800mm and 1100mm from the finished floor level Royal & Sun Alliance Insurance plc

4 TABLE 1 : Annealed Glass Thickness/Area Limits [Building Regulations] Nominal Thickness Maximum Size 8mm 1.10m x 1.10m 10mm 2.25m x 2.25m 12mm 3.00m x 4.50m 15mm Any size TABLE 2 : Annealed Glass Thickness/Area Limits [BS 6262] Single Glazing Hermetically Sealed Factory Made Double Glazed Units Nominal thickness mm Maximum area m 2 Nominal thickness mm Maximum area m Royal & Sun Alliance Insurance plc

5 These and other Risk Management Guidelines addressing a wide variety of risk control issues are freely available from: The information set out in this document constitutes a set of general guidelines and should not be construed or relied upon as specialist advice. Therefore RSA accepts no responsibility towards any person relying upon these Risk Management Guidelines nor accepts any liability whatsoever for the accuracy of data supplied by another party or the consequences of reliance upon it. Royal & Sun Alliance Insurance plc (No ) Registered in England and Wales at: St Mark s Court, Chart Way, Horsham, West Sussex, RH12 1XL Authorised & Regulated by the Financial Services Authority