FD30 and FD120 are both certified fire doorsets, rated to resist fire for at least 30 and 120 minutes of integrity respectively. The difference is duration: FD120 holds the line for 120 minutes where FD30 holds it for 30. FD30 is specified for flat entrances, HMO and escape-route doors, corridors and most internal fire doors; FD120 for major compartment walls, basements and high-hazard storage and process areas. The correct rating for any opening comes from the building's fire strategy and risk assessment, not a general rule.
FD30 vs FD120 at a glance
| FD30 | FD120 | |
|---|---|---|
| Fire resistance | 30 minutes | 120 minutes |
| EN classification | ≈ E30 (integrity) | Per certified design |
| Typical leaf | Typically 44 mm | Per certified design |
| Where it is specified | flat entrances, HMO and escape-route doors, corridors and most internal fire doors | major compartment walls, basements and high-hazard storage and process areas |
When FD30 is the right choice
Specify FD30 where the fire strategy calls for 30minutes' integrity — flat entrances, HMO and escape-route doors, corridors and most internal fire doors. Stepping up to a higher rating than the strategy requires adds cost and weight without adding compliance; the rating should match the assessed risk at each opening.
When to step up to FD120
FD120 is specified where the fire strategy or Approved Document B demands 120 minutes rather than 30 — major compartment walls, basements and high-hazard storage and process areas. At this rating the doorset construction is heavier and, above FD60, the design and glazing become more restricted; confirm what is achievable against the certified field of application.
Both figures describe integrity (E) — resisting flame and hot gases — not insulation (EI), which limits heat transfer and is separately tested. Leaf thicknesses are typical, not mandatory; the certified design governs. Also see FD30 vs FD60, compare all ratings, the full range (FD30–FD120), or run the compliance checker.
Frequently asked questions
Is FD120 better than FD30?
Not automatically. FD120 resists fire longer — 120 minutes of integrity versus 30 — but specifying a higher rating than the fire strategy requires adds cost and weight without adding compliance. The correct rating for an opening comes from the building's fire strategy and risk assessment, not the largest number.
What is the difference between FD30 and FD120?
Duration of fire resistance: FD30 provides 30 minutes of integrity and FD120 provides 120, tested to BS 476-22 or BS EN 1634-1. FD30 is specified for flat entrances, HMO and escape-route doors, corridors and most internal fire doors; FD120 for major compartment walls, basements and high-hazard storage and process areas.
Is FD30 or FD120 an insulation (EI) rating?
Neither. Both describe integrity (E) — resisting flame and hot gases — not insulation (EI), which limits heat transfer to the protected side and is tested separately. An FD120 doorset is not the same as EI120.