Understanding Approved Document K – Protection from Falling, Collision, and Impact

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Safety glazing in buildings is a critical component of modern architectural design, providing enhanced protection and security. It involves the use of specialised glass materials that are designed to minimise injury in the event of breakage. 

In order to protect the safety of occupants inside buildings, safety glazing is mandated by the building regulations to minimise the potential for injury in the event of glass breakage. Safety glazing requirements are outlined in Part K of the Building Regulations, with Approved Document K providing guidance on compliance.

Approved Document K gives guidance on how to comply with Parts K1, K2, K3, K4, K5.1, K5.2, K5.3, K5.4 and K6 of the Building Regulations.

Approved Document K  contains the following sections:

  • Section 1: Guidance on aspects of the geometry of stairs, special stairs, fixed ladders and handrails for and guarding of stairs
  • Section 2: Guidance on ramps and guarding of ramps
  • Section 3: Guidance on protection from falling
  • Section 4: Guidance on vehicle barriers and loading bays
  • Section 5: Guidance on protection against impact with glazing
  • Section 6: Guidance on protection from collision with open windows etc.
  • Section 7: Guidance on manifestation of glazing
  • Section 8: Guidance on safe opening and closing of windows etc.
  • Section 9: Guidance on safe access for cleaning windows etc.
  • Section 10: Guidance on protection against impact from and trapping by doors

In this blog posts, we focus the sections relating to the architectural glazing and fenestration products.

This approved document deals with the following requirement from Part K of Schedule 1 to the Building Regulations 2010.

Section 5: Protection against impact with glazing

Glazing in critical locations

5.1 Diagram 5.1 shows critical locations in terms of safety.

5.2   In critical locations, comply with one of the following:

  1. Ensure that glazing, if it breaks, will break safely (see paragraphs 5.3 and 5.4).
  2. 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).
  3. Permanently protect glazing (see paragraph 5.8).

Safe breakage

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.

  1. A small clear opening only, with detached particles no larger than the specified maximum size.
  2. Disintegration, with small detached particles.
  3. 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.

  1. It satisfies the requirements of Class 3 of BS EN 12600 or Class C of BS 6206.
  2. 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.

Notes

Critical locationsRequirements
1) Glazing in doors
(Wholly or partially within 1500mm from floor level)
– Minimum Class C of BS 6206 or Class 3 of BS EN 12600
– Marked according to BS 6206.
– If the pane width is exceeding greater than 900mm it shall be: Minimum Class B of BS6206 or Class 2 of BS EN 12600.
2) Glazing adjacent to doors
(Wholly or partly within 300mm of the edge of a door and which is wholly or partially within 1500mm from floor level)
– Minimum Class C of BS 6206 or Class 3 of BS EN 12600
– Marked according to BS 6206.
– If the pane width is exceeding greater than 900mm it shall be: Minimum Class B of BS6206 or Class 2 of BS EN 12600.
Low level glazing not covered by (1) or (2)
(Glazing which is wholly or partially within 800mm of the floor level)
(excluding guarding)
– Minimum Class C of BS 6206 or Class 3 of BS EN 12600
– Marked according to BS 6206.

Robustness

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.

  1. In a small annealed glass pane, use glass with a minimum 6mm nominal thickness except in the situation described in b.
  2. In traditional leaded or copper lights, when fire resistance is not important, you may use 4mm glass.
  3. 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.

  1. Prevent a sphere of 75mm from coming into contact with the glazing.
  2. Be robust.
  3. If it protects glazing installed to help prevent people from falling, be difficult to climb (e.g. no horizontal rails).

Notes

The critical locations shown on Diagram 5.1 require safety glazing. But, if these locations are shielded by a suitable designed permanent screen as shown on the Diagram 5.4, there is no need for safety glass to be installed.

Questions & Answers

Is annealed glass a safety glass?

Annealed glass is ‘standard’ float glass produced prior to any subsequent processing. It is not usually considered a safety glass, due to the manner in which it breaks (i.e. into large fragments).

Is ordinary wired glass a safety glass?

No. Ordinary wired glass does not meet safety glass standards.
Wired glass, which contains a wire mesh within the glass pane,  is commonly used in applications such as fire-rated doors, windows, and partitions, where fire protection is essential. It is one of the oldest types of fire rated glass. But, despite its fire-resistant properties, wired glass is significantly weaker than toughened or laminated glass.  It can be broken easily upon impact.

Further Reading

  1. Glass and Building Regulations – Impact Safety (www.pilkington.com)
  2. Approved Documents K (gov.uk)