FD30 vs FD60: Which Fire Door Rating Do You Actually Need?

Specifying a fire door sounds straightforward until you are standing in front of a drawing package, a fire strategy report, and a quote from the supplier, and the question becomes concrete: FD30 or FD60? The decision carries real cost implications, real programme implications, and, more importantly, real consequences for life safety and regulatory compliance. Get it wrong in the over-specified direction and you waste budget and lead time. Get it wrong in the under-specified direction and you are exposed under the Regulatory Reform (Fire Safety) Order 2005 and, for higher-risk buildings, the Building Safety Act 2022. This guide sets out how the two ratings differ, where each one belongs, and how to make the call when the answer is not obvious.

What the ratings actually mean

The numbers in FD30 and FD60 refer to minutes of fire resistance demonstrated under a standardised test. A doorset rated FD30 has been shown to resist the passage of fire for at least 30 minutes, and an FD60 doorset for at least 60 minutes, when subjected to the heating regime defined in either BS 476 Part 22 (the long-standing British standard) or BS EN 1634-1 (the harmonised European standard now widely adopted across the UK supply chain). Both standards measure the same fundamental property, but the European test is generally regarded as more onerous and is increasingly the reference point for modern specifications.

The rating specifically concerns integrity, which is the door's ability to prevent flames and hot gases passing from the fire side to the non-fire side. Integrity is distinct from insulation, which measures whether the non-fire face of the door stays cool enough to prevent ignition of materials on the safe side. A door labelled FD30 or FD60 has been tested for integrity only; a door tested for both properties would carry a designation such as EI30 or EI60 under the European system. For the vast majority of internal compartmentation in UK buildings, integrity alone is what the fire strategy calls for.

You will also see the suffix "S" appended to many ratings, giving FD30S or FD60S. The S denotes that the doorset is fitted with cold smoke seals, typically combined intumescent and brush seals around the perimeter, to restrict the movement of smoke at ambient temperatures during the early stages of a fire. Smoke kills far more people in building fires than flames do, and the S suffix is mandatory in many of the locations where fire doors are used in practice, particularly on flat entrance doors and doors onto protected escape routes.

When FD30 is the right choice

For most UK projects, FD30S is the correct specification, and the guidance flows from Approved Document B of the Building Regulations. In residential blocks of flats where the top storey is no more than 11 metres above ground level, flat entrance doors opening onto a common escape route are required to be FD30S. The same 30-minute rating covers the majority of internal compartment doors in low and medium-rise housing, small offices, retail units, and light commercial premises where the compartmentation strategy is built around 30 minutes of fire resistance between rooms or between a room and a protected corridor.

There are practical reasons the standard lands at 30 minutes for so many applications. An FD30 doorset is lighter than its 60-minute counterpart, which means less strain on hinges and frames, easier self-closing action, and a door that occupants are more likely to actually keep shut rather than wedging open. It is cheaper to manufacture, cheaper to install, and generally quicker to source. For a landlord refurbishing a portfolio of flats or a contractor fitting out a suite of offices, the cost and weight advantages of FD30 fire doors are not trivial, and over-specifying to FD60 where the fire strategy does not demand it is simply waste.

The key word is "where the fire strategy does not demand it". Approved Document B sets a baseline, but the fire strategy for any specific building may call for something more onerous based on the layout, the occupancy, the travel distances, or the compartmentation philosophy. FD30 is the right answer when the regulations and the strategy both point to 30 minutes, not by default.

When FD60 is required

FD60 enters the picture when the consequences of failure are more severe, typically because evacuation takes longer or because the compartment protects something critical. In residential buildings taller than 11 metres, the protected stairwell and the doors serving it are commonly specified to 60 minutes, reflecting the fact that occupants above that height take measurably longer to escape and that firefighters need a defensible route up. Lift lobbies in taller buildings, doors onto firefighting shafts, and doors between residential compartments and ancillary areas such as bin stores or plant rooms frequently demand FD60 for the same reason.

Commercial kitchens, plant rooms housing boilers or generators, electrical switchrooms, and areas storing flammable materials are standard FD60 territory because the fire load inside those rooms is high and the probability of ignition is elevated. Care homes, hospitals, and other buildings with dependent occupants sometimes specify FD60 on compartment lines even where the height alone would not require it, because horizontal progressive evacuation relies on compartments holding long enough for staff to move residents from the affected zone to an adjacent one. In higher-risk buildings as defined under the Building Safety Act 2022, the Accountable Person has a direct legal interest in ensuring that compartmentation doors perform as the fire strategy claims they will, and FD60 fire doors are frequently the means by which that performance is delivered.

The guiding principle is compartmentation severity. If the door is holding the line between a source of high fire load and a route that must remain tenable long enough for phased or delayed evacuation, 60 minutes is the sensible floor.

The grey areas and how to decide

In practice, a great many decisions fall between the clean cases above, and this is where the fire strategy document earns its keep. On projects where no formal strategy has been produced, or where the strategy is silent on a particular door, the default should be to engage a competent fire engineer rather than guess. Insurance policies sometimes stipulate a higher rating than Building Regulations require, particularly for commercial premises with significant stock value or business interruption exposure, and those stipulations are binding on the policyholder regardless of what Approved Document B says.

Client and landlord preference also plays a part. Some clients instruct their design teams to over-specify to FD60 as a matter of policy, reasoning that the marginal cost is worth the reduced liability and the simpler compliance story later in the building's life. That is a defensible position, but it should be a conscious decision rather than a drift. The cost delta is not negligible: an FD60 doorset is typically 30 to 60 per cent more expensive than the equivalent FD30, and lead times on certified 60-minute assemblies can be longer, particularly for non-standard sizes or vision panel configurations.

When weighing the decision, work through the same questions a fire engineer would ask. What does Approved Document B require for this building type and height? What does the project's fire strategy say? Is the door on a protected escape route, a compartment line, or an ancillary opening? What is the fire load on either side? Does the insurer have a view? If the answers to those questions do not converge on a clear 30 or 60, escalate the query in writing and get a specialist to sign off.

The practical answer for most UK projects is that FD30S is the correct specification, with FD60S reserved for the locations where the fire strategy, Approved Document B, or a specific insurance or regulatory requirement demands it. Upgrading every door to 60 minutes is rarely good value and rarely necessary, but under-specifying is a route to enforcement action, invalid insurance, and, in the worst case, loss of life. If you are uncertain about what your project needs, send us the drawings and the fire strategy extract and request a quotation; we will specify the correct rating, the correct seals, and the correct hardware package, and give you a straight answer on lead time and cost before you commit.