Decoding FD30 and FD60: Understanding the ratings that protect your escape route
SaveFD30 and FD60 tell you how long a fire door will resist fire and smoke before it fails. The number is minutes of protection: an FD30 door holds for half an hour, an FD60 for a full hour. You find these codes stamped on the door edge, printed on the certification label, or written in the frame rebate. Fred Duncombe explains what each rating means in practice, where each is required, and how you verify the one fitted to your building.
Reading the rating: what the letters and numbers tell you
FD stands for fire door. The number that follows is the duration in minutes that the door assembly — leaf, frame, seals and hardware together — will contain fire and smoke under test conditions. An FD30 rating means thirty minutes of integrity; FD60 means sixty minutes.
Integrity is the door's ability to stop flames, hot gases and smoke passing through gaps, joints or the material itself. The test measures when the first flame breaks through to the other side, when a cotton pad placed near a gap ignites, or when the door collapses.
The rating applies to the whole assembly, not just the leaf. Fit an FD30 door into a frame built for fifteen minutes, or hang it with hinges rated lower, and the certification no longer holds.
Where you find the rating
Look first at the top or hinge edge of the door leaf. Most carry the rating stamped or routed into the timber. A certification label fixed to the top edge or the frame gives the rating, the test standard and the certifying body.
When no label remains visible, check the original specification documents or the building control records. Replacing missing labels without re-certifying the door is not allowed.
Choosing between FD30 and FD60: what your building requires
Building regulations and fire risk assessments determine which rating you need. The choice depends on the door's location, the building's height, how it is used, and how long occupants need to escape.
FD30 doors are the minimum standard for most domestic and small commercial buildings. You fit them between rooms and habitable spaces, at the base of a stairwell in a house, and between a kitchen and a hallway.
FD60 doors are required where escape routes serve taller buildings, where compartmentation protects a means of escape for longer, or where the fire load in an adjoining room is higher. Common locations include stairwells in blocks of flats above a certain height, plant rooms, and boundaries between different occupancies in mixed-use buildings.
| Rating | Protection time | Typical locations |
|---|---|---|
| FD30 | Thirty minutes | Between rooms in houses, ground-floor stairwells, internal doors in small offices |
| FD60 | Sixty minutes | Stairwells in tall residential blocks, plant rooms, high-risk boundaries |
What the test measures and what it leaves out
Fire resistance tests expose the door to a controlled furnace that follows a standard temperature curve. Thermocouples measure heat on the non-fire side, observers watch for flame breakthrough, and engineers record the time to failure.
The test checks integrity — whether fire and smoke break through — but not insulation in most domestic ratings. An FD30 door may become too hot to touch on the non-fire side well before thirty minutes have passed. Where insulation matters, the rating states it explicitly, written as FD30S or with a separate insulation figure.
Real fires do not follow the test curve. A fast, intense fire in a room full of synthetic furnishings may challenge a door sooner than the rating suggests. The rating is a benchmark, not a guarantee of survival time in every scenario.
Maintaining the rating: what breaks it and how you preserve it
Alterations void the certification unless re-tested or covered by an extended scope. Drilling a hole for a cable, cutting a vision panel without a compatible glazing kit, or planing more than a small margin from the edge all compromise the rating.
Intumescent strips and smoke seals must remain intact. When you see a strip peeling, torn, painted over or missing, replace it with one that matches the door's test specification. Gaps around the frame wider than the test allowed reduce the protection time.
Every hinge, closer and latch must meet the rating. Replacing a three-hinge set with two hinges, or fitting a residential latch to a door tested with commercial hardware, removes the certification. Check that replacement parts state compatibility with the rating you are maintaining.
Verifying your door after work
After maintenance or hardware changes, verify compliance by checking the label remains legible, all seals sit flush, the door closes fully into the frame without catching, and no new holes or cuts have been made outside the certificated scope.
Reading the certification label: what else it tells you
Beyond the FD rating, the label names the test standard, the certifying body, the manufacturer, and a unique certificate or plug number. The test standard in the UK is most often BS 476-22 or the European EN 1634-1.
The certificate number lets you trace the original test report. Where doubt exists about whether a particular alteration is allowed, the certifying body or the door manufacturer can confirm what the tested assembly included and what scope for variation the certificate permits.
Some labels state "FD30 with 15mm lippings" or "approved for vision panel to drawing XYZ". These notes define the limits within which the rating holds. Work outside those limits requires a new test or a field-of-application assessment.
Installing a fire door to preserve its rating
Correct installation starts with a compatible frame. The frame must be built or supplied to the same test specification, with the correct rebate depth, threshold detail and fixing method.
- Check the door and frame certification labels match in rating, test standard and any specific assembly requirements before you begin.
- Fit intumescent strips and smoke seals into the grooves provided, ensuring they run continuously around the head and both jambs with neat mitred corners.
- Hang the door on the correct number of hinges, positioned at the heights and offsets the certificate specifies, and tighten fixings into solid timber or masonry, never just into plasterboard.
- Fit the latch and closer to the backset and projection distances stated, and adjust the closer so the door latches positively from any open position without slamming.
- Verify an even gap around the perimeter, check the door closes fully into the frame, and confirm the latch engages without forcing.
Where you need detailed measurements before fitting, measuring correctly avoids the need to adjust the door afterward.
When you see FD30S or other suffixes
The letter S after the number means the door also meets an insulation standard: the non-fire face will not exceed a certain temperature rise for the stated duration. FD30S offers both integrity and insulation for thirty minutes, protecting occupants from radiant heat as well as flame.
Less common suffixes include Sa for smoke control at ambient temperature, or additional codes that denote acoustic or security performance tested alongside fire resistance. Each suffix adds a requirement; the door must meet all of them to carry the full rating.
Upgrading an existing door: when it is possible and when it is not
You cannot upgrade a standard door to FD30 by adding strips and a closer. Fire doors are manufactured with specific core materials, edge lippings and construction methods that allow them to resist fire for the rated duration. A door without those features will fail the test regardless of the hardware you fit.
Upgrading from FD30 to FD60 is possible only if the door was manufactured with a core and construction capable of sixty-minute resistance and was simply certified to the lower standard. The manufacturer or certifying body can confirm whether the door qualifies for extended certification.
Where an upgrade is needed and the door does not support it, replacement is the only compliant option.
Recognising when a fire door is not performing to its rating
A door that does not close fully, latches intermittently, or shows daylight around the edges when shut is not providing the protection its rating promises. Warped leaves, damaged seals, missing closers and oversized gaps all reduce the time the door will contain fire and smoke.
When you identify faults, addressing them promptly restores the door's function. Leaving a fire door wedged open or fitted with a hold-open device not linked to the fire alarm removes all protection, regardless of the rating stamped on the edge.
Download PDF: Fire Door Rating Checklist PDF, 28 KB
Further reading
Frequently asked questions
What is the difference between FD30 and FD60?
FD30 resists fire for thirty minutes, FD60 for sixty minutes. The number tells you how long the door will contain flames and smoke under test conditions before it fails.
How do I know what fire door rating I need?
Building regulations and your fire risk assessment determine the rating. FD30 is the minimum for most houses and small commercial buildings; FD60 is required in taller residential blocks, stairwells serving multiple floors, and higher-risk locations.
Can I change an FD30 door to FD60?
Only if the door was manufactured with a core and construction capable of sixty-minute resistance. Most FD30 doors cannot be upgraded; you need to replace the door with one certificated to FD60.