The short answer
In an explosion, many injuries come from flying glass, so blast mitigation aims to keep broken glass in its frame. The main options are anti-shatter film, laminated glass tested for blast, and frames and fixings strong enough to hold it. The level needed comes from a threat assessment, usually drawing on guidance from the National Protective Security Authority (NPSA).
Why is glass the main hazard?
A blast wave can break ordinary glass across a wide area, and the fragments travel at speed into the rooms behind. Keeping those fragments in place, or catching them, reduces injuries even where the glass itself breaks.
What are the options?
- Anti-shatter film applied to the inside of existing glass
- Film anchored to the frame so the whole pane is held in place
- Laminated glass tested for explosion pressure
- Strengthened frames and fixings designed to hold laminated glass under load
- Bomb blast net curtains, used with film in some buildings
What do ER1 to ER4 mean?
BS EN 13541 classifies glass by the explosion pressure it withstood in a shock-tube test, from ER1 up to ER4. ISO 16933 and ISO 16934 are also used for arena and shock-tube testing. In these tests the glass usually breaks; the point is that it stays in the frame and does not breach. That only works in practice if the frame and fixings are designed for the same load.
Who needs blast mitigation?
Government and public buildings, critical infrastructure, offices near high-profile sites and some venues, usually after advice from a security adviser. For most homes and shops it is not needed.
How is it specified?
The level comes from your threat assessment, normally with a specialist security adviser and a structural engineer for the frames and fixings. We quote film, laminated glass and framing tested by their manufacturers to the level in the design, with their test evidence supplied. Guide prices are £45 to £110 plus VAT (£54 to £132 inc VAT) per m² for film and £450 to £1,495 plus VAT (£540 to £1,794 inc VAT) per m² for blast-resistant glazing, with framing priced at survey.
Sources
- Measures to improve the blast resistance of glazing (National Protective Security Authority)
- 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.
Add Security Glazing UK as a preferred source on Google
Related glass types
Laminated glass, retention systems and frames designed to hold together under explosion pressure and cut flying-glass injuries.
from £450 + VATLearn moreClear polyester film applied to the inside of existing glass so a broken pane holds together and is slower to get through.
from £54 per m² inc VAT, min. job £354Learn moreReplacing damaged, failed or unsafe glass in offices, shops and public buildings, including large panes needing lifting equipment.
from £395 + VATLearn moreHeavy-duty aluminium or steel glazed doorsets and side screens with laminated glass and multi-point locking for entrances.
from £1,495 + VATLearn more