# Fire-Rated Glass: Integrity vs Insulation

> Fire-rated glass is glazing tested to keep a fire compartment intact for a stated time. An integrity (E) rating means it stops flames and smoke passing; an insulation (EI) rating also limits the heat transmitted to the protected side, so people can pass close to it during a fire.

## Why it matters

Glass walls along corridors, stairs and lobbies often sit on fire compartment
lines. There, ordinary glass would fail within minutes; fire-rated glazing keeps
the compartment intact long enough for people to escape.

## How it works in practice

| Rating | Stops flames & smoke | Limits heat | Typical use |
| --- | --- | --- | --- |
| E (integrity) | Yes | No | Where people do not pass close by |
| EI (insulation) | Yes | Yes | Escape routes, adjacent occupied areas |

## Common mistakes

- **Rated glass in an unrated frame.** The system, not the glass, carries the
  rating.
- **E where EI is needed.** Heat on escape routes can be dangerous.
- **Unrated penetrations** through fire-rated glass walls.

## Standards referenced

Fire resistance classification under **EN 13501-2**. Compartmentation under
**NBC 2016, Part 4**.

## Frequently asked questions

### What is the difference between E and EI glass?

E-rated glass keeps flames and smoke out but can become very hot on the protected side. EI-rated glass also insulates, keeping the protected face cool enough for escape routes and adjacent occupied areas. EI is thicker and more expensive.

### Is the glass rating enough?

No. Fire rating applies to the tested assembly — glass, frame, gaskets and fixings together. Putting rated glass into an unrated frame does not produce a rated wall.

## Sources

- [EN 13501-2](https://standards.cencenelec.eu/ords/f?p=CEN:105) — Fire resistance classification
- [NBC 2016, Part 4](https://www.bis.gov.in/standards/national-building-code/?lang=en) — Fire and life safety — compartmentation

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Source: https://hagerstone.com/glossary/fire-rated-glass