The door schedule says EI60 and the contractor asks whether 120 minutes would be better. It sounds like a sensible upgrade and it usually wastes money. The minute figure is not a quality grade; it comes from the building's compartment strategy. If the stair enclosure wall is rated for 60 minutes, fitting a 120 minute door does not strengthen the chain. The wall remains the weak link.
What the minutes measure
The rating is the time the door maintained integrity, and insulation where its class requires it, in a furnace following a standard heating curve. A real fire does not follow that curve; it develops faster or slower depending on fuel load, ventilation and intervention. So a 60 minute label does not promise exactly 60 minutes in a real event. It records that the assembly passed that class under test conditions, which is why the rating is read off the fire strategy rather than guessed.
What changes as the rating rises
- Leaf thickness increases from the lower classes upward.
- Core: rock wool density rises, and higher classes introduce mineral board or gypsum-based layers.
- Layer count: upper classes use multiple insulating layers with intermediate sheet steel.
- Seals: intumescent sections grow, sometimes doubling up.
- Hardware: more hinges, and the lock and handle set must be tested in the same class.
- Weight: leaves get considerably heavier, so frame gauge and anchoring are upgraded with them.
Where each class is typically required
The exact value always comes from the architectural drawings and fire report, but the logic runs like this. Lower ratings cover transitions between dwellings and lobbies, and corridor subdivisions. Mid classes are common on escape stairs and fire-fighting lobbies. Higher classes appear on boiler rooms, generator rooms, transformer rooms and fuel stores. The highest classes show up in tall buildings and shelter entrances. What drives the order is the fire load behind the door and the integrity period of the compartment.
Both directions of error
Specifying below requirement fails inspection and the whole door is replaced, one of the most common causes of rework on site. Specifying above requirement brings hidden costs: heavier leaves need stronger frames and anchoring, larger closers, and more effort to open daily. In a busy corridor an over-heavy door gets wedged open by its users, which is a direct safety problem.
Criteria that have nothing to do with minutes
Smoke leakage is a separate classification, and in an escape route smoke arrives before flame. Self-closing and self-latching behaviour depends on correct closer adjustment. Panic hardware on the escape face with keyed access on the other side is planned separately. Without a sequence selector, double leaves close in the wrong order and the latch misses its keep. None of these are solved by raising the class.
Ordering for export projects
Send us the door schedule with the class and rating as written, the wall construction, the hand of each door, and whether smoke leakage is required. Our standard fire door has a clear frame opening of 90×200 cm and a 104×208 cm architrave edge; other openings have class and size assessed together. Our fire door range covers single and double leaf sets with panic hardware, and for common areas outside the escape route sheet panel doors are sufficient. Doors ship crated from Istanbul with hardware boxed and installation manuals included.
