Building Regulation Part K for Glazing – Requirement K4

Approved document K of the Building Regulations outlines the requirements for protection from falling, collision and impact. This article will focus on requirement K4 which covers protection against impact with glazing.

Requirement K4 outlines building regulations for both residential dwelling and public or non-residential buildings. The regulations only apply to glazing that people are likely to come into contact with whilst moving around the building, entering or exiting.

Requirements for the Glazing

Glazing that building occupants are likely to come into contact with must meet one of three requirements:

  1. If broken upon impact it will break in a way that will not injure anyone
  2. Resist impact without breaking
  3. Be shielded or protected from impact

Using toughened glass is one way to ensure the glass will break in a way that is unlikely to injure anyone, as these panes shatter into rounded, extremely small pieces.

Toughened glass also creates glazing that resists impact without breaking. For a stronger pane, laminated glass can also be used.

To shield or protect the glazing from impact, the amount of contact people have with the glazing can be lowered or a barrier can be placed around the glazing.

Glazing that is between floor and shoulder height (usually doors and side panels) near handles and push plates pose the biggest threat to people, as pushing or shoving them to open if they stick can cause the glazing to shatter and injure people.

shattered toughened tempered glass

Critical Locations and Safe Breakage

The shaded areas of the diagram show critical locations to which the requirements outlined in K4 apply.

For the shaded areas, the glazing must comply with one of the following:

  • Ensure that if it breaks it breaks safely
  • Be robust or small panes
  • Protected glazing at all times

building regulations part K for glazing diagram

Many systems can be designed to comply with these regulations through the use of toughened glass.

Safe breakage is based on impact resistance. As defined in BS EN 12600 section 4 and BS 6206 clause 5.3, in an impact test the breakage is considered safe if:

  • It creates a small clear opening, with no large glass shards
  • The glass disintegrates with small, detached particles
  • The glazing breaks into separate pieces that aren’t sharp or pointed

Any glazing that meets the requirements for BS EN 12600 Class 3 or BS 6206 Class B is considered suitable for these critical locations. Glazing is also considered suitable when it is installed in a door or door side panel with a pane width of over 900mm and it meets the requirements for BS EN 12600 Class 2 or BS 6206 Class B.

Toughened Glass

When using float glass there are restrictions on size, as this type of glass breaks into large sharp pieces when broken upon impact.

IQ use toughened glass as standard on all glazing systems to ensure that in the event of breakage the glass breaks into smaller pieces that are less likely to injure people.

Two pieces of toughened glass can also be laminated which would hold the shattered panes in place if the glazing is in a location where it is likely to be impacted upon.

saftey glass broken into extremely small pieces

Permanent Screen Protection

Glazing in the aforementioned critical areas do not need to comply with the requirements in K4 if they are protected by a permanent screen.

The screen does need to meet certain requirements for this to be the case.

The permanent screen would need to prevent a sphere of 75mm from impacting the glazing, so bars that are spaced further than 75mm apart would not be adequate.

The permanent screen must also be robust, so cannot be made of a material that is flexible or easily broken.

Lastly, the screen must be difficult to climb so if using bars they must be vertical bars, not horizontal.

For more information get in touch with the IQ team who will be able to assist you with the glazing for your project.

Rebecca Clayton
Technical Sales

Rebecca is the Communications Director at the IQ Group and has worked in glazing specification for many years. She has a broad range of technical knowledge about all our glazing products and offers technical advice and guidance to architects for specification. Her easy to digest technical advice is often quoted in magazines and publications. You might also recognise her as one of the IQ Glass CPD presenters.

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