The short answer
BS EN 356 classifies glass by how well it resists manual attack. Classes P1A to P5A come from dropping a 4.11 kg steel ball onto the glass, and P6B to P8B from repeated hammer and axe strikes. The higher the class, the longer the glass holds out.
How does the drop-ball test work for P1A to P5A?
A steel ball weighing 4.11 kg is dropped three times onto the glass in a triangle pattern. To pass, the ball must not go through. The drop height sets the class:
- P1A: 3 drops from 1.5 m
- P2A: 3 drops from 3 m
- P3A: 3 drops from 6 m
- P4A: 3 drops from 9 m
- P5A: 9 drops (three sets of three) from 9 m
How does the axe test work for P6B to P8B?
For the higher classes a machine swings a hammer to break the glass and then an axe to cut through it, counting the strikes needed to make an opening 400 mm by 400 mm. More strikes means a higher class:
- P6B: 30 to 50 strikes
- P7B: 51 to 70 strikes
- P8B: more than 70 strikes
Which rating do I need?
There is no single answer, because it depends on the risk, what is behind the glass and what your insurer asks for. As a broad guide:
- Ground-floor and easily reached windows in homes: P1A to P2A
- Glazing in doors and near locks: P2A to P4A
- Shopfronts and offices: P4A to P6B
- Jewellers, pharmacies and other high-value stock: P6B to P8B, often set by the insurer
- Glass that also has to resist firearms: a BS EN 1063 bullet-resistant rating as well
What glass makeup achieves each class?
As a rough guide, P2A is often a 6.8 mm laminate with a 0.76 mm interlayer, P4A is around 8.8 to 9.5 mm, P6B starts at around 9.5 to 11.5 mm with several interlayers, and P8B is commonly 20 mm or more. These figures are indicative only. A class belongs to the specific makeup the manufacturer tested, so we always quote against the manufacturer's tested product and send their test evidence with your quote.
Does a rated pane make the window secure?
Not on its own. BS EN 356 tests the glass, not the frame. A P6B pane in a frame with external beads that unclip, weak hinges or poor locks can be bypassed. Complete doors and windows are tested to other standards, such as PAS 24 for homes, which look at the frame, glass, hardware and fixings together. That is why our survey checks the frame and beads as well as the glass.
How can I tell what rating my glass has?
Rated glass is usually marked in a corner, and the manufacturer's paperwork confirms the class. If there is no marking and no paperwork, assume the pane is unrated. Our guide to telling laminated from toughened glass explains what to look for.
Sources
- BS EN 356:2000 Glass in building. Security glazing. Resistance against manual attack (BSI)
- Approved Document Q: security in dwellings (GOV.UK)
- Building standards technical handbook 2022, domestic: 4.13 security (gov.scot)
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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