Where does safety glass have to be used? Critical locations explained

What counts as a critical location?

Critical locations are where people are most likely to walk or fall into glass. Approved Document K for England defines them as:

• Glass in a door, from the floor up to 1,500 mm
• Glass in a side panel within 300 mm of either edge of a door, up to 1,500 mm from the floor
• Any other glass, such as a low window or screen, below 800 mm from the floor

What kind of glass meets the rule?

Glass in a critical location should break safely, be robust, or be permanently protected. Safety glass is tested under BS EN 12600: class 3 is generally enough, but door and side-panel panes wider than 900 mm should reach class 2. Toughened and laminated glass both qualify at the right thickness. Small panes of ordinary glass can be acceptable within strict size limits, and a fixed guard is another option.

What are the rules in Wales, Scotland and Northern Ireland?

Wales covers glazing safety in its own Approved Document N, with critical locations set out in the same way: windows below 800 mm, glass within 300 mm of a door up to 1,500 mm, and glass in doors up to 1,500 mm.

In Scotland, standard 4.8 of the building standards technical handbooks expects glass within 800 mm of the floor, in a door leaf, or within 300 mm of a door leaf and 1.5 m of the floor to resist human impact as set out in BS 6262-4. Northern Ireland's Building Regulations include a glazing part (Part V) with its own technical booklet taking a similar approach. Your council's building control or building standards team has the final word on new work.

Does this apply in workplaces too?

Yes. In Great Britain, regulation 14 of the Workplace (Health, Safety and Welfare) Regulations 1992 says windows and transparent surfaces in walls, partitions, doors and gates must, where needed for health or safety, be of safety material or protected against breakage, and be marked so people notice them. Northern Ireland has equivalent workplace regulations. Large panes are usually marked with manifestation at two heights, roughly 850 mm to 1,000 mm and 1,400 mm to 1,600 mm from the floor.

Does replacement glass have to be safety glass?

If the pane is in a critical location, the replacement should be safety glass, whatever was there before. Older homes often have ordinary glass in doors and low windows; replacing it like for like would repeat a known hazard. When we replace glass in a critical location we fit safety glass marked with its standard and class.

How do I know if my glass is safety glass?

Look for a marking etched or printed in a corner of the pane. Our guide to telling laminated from toughened glass explains what the markings mean. If there is no marking, treat the glass as ordinary glass until a glazier has checked it.

Sources

• Approved Document K: protection from falling, collision and impact (GOV.UK)
• Building regulations guidance: doors and windows (GOV.WALES)
• Building standards technical handbook 2022, domestic: 4.8 danger from accidents (gov.scot)
• Building Regulations technical booklets, including Technical Booklet V: glazing (Department of Finance NI)
• Workplace (Health, Safety and Welfare) Regulations 1992, regulation 14 (legislation.gov.uk)

This guide is general information, not legal advice. Rules differ between England, Wales, Scotland and Northern Ireland; check with your council, building control or insurer where it matters.

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