Glossary — Construction & Standards
Fire Resistance Rating
A fire resistance rating tells you how long a building element — wall, floor, door, or glazing — can withstand fire conditions in a standardised test. Understanding these ratings is essential for reading building specifications, checking compliance, and interpreting fire door labels.
Definition
Fire resistance rating — a measure of the time, in minutes, that a building element maintains one or more fire performance criteria (load-bearing capacity, integrity, or insulation) when exposed to a standardised fire test. Expressed in UK practice as FD30, FD60 (doors) or in European notation as R/E/I followed by time (e.g. REI60, EI30).
The three core performance criteria (EN 13501)
Element continues to support its structural load without collapse
Element resists passage of flames and hot gases; no cracks or holes form
Element limits heat transfer to the unexposed face (max 140 °C average rise)
Element limits radiated heat flux (used for glazing, rarely for other elements)
Common fire resistance ratings at a glance
| Rating | Typical element | Meaning |
|---|---|---|
| FD30 | Timber fire door (UK) | Resists fire for 30 minutes; "S" suffix (FD30S) adds smoke seal |
| FD60 | Enhanced fire door (UK) | Resists fire for 60 minutes; used in higher-risk occupancies |
| EI30 | Partition, wall, or glazing (EN) | Integrity and insulation for 30 minutes |
| EI60 | Partition, wall, or glazing (EN) | Integrity and insulation for 60 minutes; typical compartment wall requirement |
| REI90 | Structural floor or beam (EN) | Load capacity + integrity + insulation for 90 minutes; typical for multi-storey construction |
| E30-W | Fire-rated glazing (EN) | Integrity + radiation control for 30 minutes (no insulation requirement) |
| REI120 | Concrete or masonry element (EN) | Full performance maintained for 120 minutes; common in high-rise construction |
UK vs European classification systems
Until 2013, the UK used BS 476 Parts 20–23 as the primary fire test standard. Following harmonisation with EU standards, EN 1363, EN 1364 (elements), EN 1634 (doors) and the classification standard EN 13501 series became the primary route. Both systems remain valid in the UK post-Brexit — products may carry UKCA or CE marks referencing either standard.
For practical purposes: FD30 and FD60 on door labels refer to UK classifications; EI30, EI60 on partition specifications refer to the EN system. Building Regulations Approved Document B accepts both, but specifiers must ensure the correct performance class is being claimed.
Fire compartmentation and ratings
Fire resistance ratings are most useful in the context of compartmentation — dividing a building into fire-resistant cells that contain a fire and protect escape routes. A compartment wall rated EI60 is designed to hold a fire for 60 minutes, giving occupants time to escape and firefighters time to intervene.
Compartmentation fails when:
- Fire-rated doors are propped open (removing the door's contribution)
- Penetrations for cables, pipes, or ducts are not fire stopped
- Intumescent seals on doors are missing, damaged, or past their service life
- Walls are not carried through to the structural slab above a suspended ceiling
For practical guidance on maintaining compartmentation in the home, see our fire door safety guide and the loft fire safety guide for party wall fire stopping.
How fire load affects required ratings
Buildings with higher fire loads — warehouses, paper archives, furniture showrooms — require longer fire resistance periods to give equivalent levels of protection. Approved Document B and BS 9999 both provide tables linking occupancy type, height, and purpose group to required fire resistance periods. A standard two-storey house requires 30 minutes; purpose-built flats require 60 minutes in floors and party walls.
Frequently asked questions
FAQ