Fire resistance (Dutch: brandweerstand) is the ability of a building element to continue performing its intended function for a specified period of time when exposed to a standard fire. It is one of the most important properties in fire safety engineering, directly influencing how long a structure remains safe during a fire.
Fire resistance criteria
Fire resistance is assessed against three criteria, each designated by a letter:
- R (Resistance) — load-bearing capacity: the element continues to support its structural load without collapse
- E (Integrity) — the element prevents the passage of flames and hot gases to the unexposed side
- I (Insulation) — the element limits heat transfer so the unexposed surface stays below critical temperature thresholds
A classification such as REI 60 means the element satisfies all three criteria for at least 60 minutes under standard fire conditions.
Common fire resistance classes
| Classification | Duration | Typical use |
|---|---|---|
| R 30 / REI 30 | 30 minutes | Single-family dwellings, low-risk areas |
| R 60 / REI 60 | 60 minutes | Multi-storey residential buildings, offices |
| R 90 / REI 90 | 90 minutes | High-occupancy buildings, hospitals |
| R 120 / REI 120 | 120 minutes | High-rise buildings, underground car parks |
Application
Fire resistance requirements are defined in national building codes and depend on factors such as building height, use, occupancy, and available fire-fighting facilities. Structural engineers select materials and dimensions to achieve the required fire resistance period. Concrete, masonry, and protected steel are commonly used to meet higher fire resistance classes.
Related Terms
- Fire rating
- Fire test
- Fire prevention
- Fire spread
- Compartmentation
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