Myth:  If, on inspection, it is found that a fire-resisting doorset does not satisfy current standards and/or is not certificated as such, so that it could not be classified as an FD30S doorset, or FD60S doorset, as relevant to its location, fire safety legislation requires that it be upgraded or, often, replaced. 

Short answer:  No, fire safety legislation requires that the adequacy of fire precautions in existing buildings is determined by a fire risk assessment, not by an assessment/audit of compliance with guidance that applies to new buildings.

Long answer

This myth is growing in prevalence, resulting in unnecessary expenditure, often of a significant amount, in existing buildings (to which current building regulations do not apply unless, or until, new building work is carried out or there is a material change of use). 

This is causing serious concern for experienced and competent fire risk assessors, such as those of the FIA Fire Risk Assessment Council, as well as for regulators, building owners and other dutyholders, and leaseholders of flats. 

Common causes of misconception

The misconception is often based on three or four factors, namely:

• The meaning of fire resistance;
• Inappropriate use of guidance (e.g. application of guidance for new buildings to existing buildings);
• A lack of understanding of the distinction between legislative requirements, guidance that supports these requirements and the effect of departures from guidance on fire risk;
• In England, in blocks of flats over 11 m in height, the requirements of the Fire Safety (England) Regulations 2022.

The meaning of fire resistance

Fire resistance (of elements of structure, compartment walls and floors and fire-resisting doorsets[1]) is one of the most important parameters in the fire safety design of buildings.  However, it is very commonly misunderstood.

The fire resistance of fire doors is determined in a standard test, in which the door is exposed to the heating regime of a furnace, which follows a defined time/temperature curve. 

It is important to understand that the standard fire test bears no direct relationship to any real fire, but is simply a means of enabling a performance requirement to be specified and of comparing the fire performance of one fire door with another.  The criteria for failure of the test do not resemble a major failure of the door substantially to hold back the flames of the furnace.

In a real fire, if the flames of a well-developed fire were in close contact with the fire door, the door might fail to satisfy the failure criteria of the standard test earlier than the period determined in the test. 

However, most commonly, a fire door will withstand a fire in a compartment for longer (often substantially longer) than the period determined in the test.  By way of example, it is common experience that a hollow-core domestic door, with a fire resistance of less than 10 minutes, will withstand a burnout of the contents of a domestic room, such as a lounge, without any significant damage to the adjacent space, such as a hallway.

It follows that small departures from the minimum periods of fire resistance, as determined in the standard fire test, specified in guidance (see below), may have little or no material effect on fire risk; this is a matter for determination in a fire risk assessment by a competent fire risk assessor.

If a new fire door is not installed in accordance with the guidance of the manufacturer, which takes into account the exact specification of the door that was tested and variations deemed acceptable by a certification body, the fire resistance of the door might be impaired; the certification of the door is then void.  The actual fire resistance of the door might then be described as “unchartered territory”, as there will be no test evidence for an incorrectly installed door.

This would be unacceptable, as, regardless of whether or not any fire risk results, the purchaser has not been provided with a fire door that will perform as expected.  A thorough fire door inspection may reveal such circumstances, and remedial work should then be carried out.

On the other hand, in the case of existing fire doors, certification or labelling of the doors may not be available.  Fire safety legislation does not require such certification or labelling, and its absence is certainly not justification for replacement of the fire door. 

Similarly, in this case, while a thorough fire door inspection might reveal departures from existing standards and codes of practice (which often did not exist at the time of manufacture and installation of the fire door), this does not necessarily justify any upgrading, or replacement, of the fire door. 

Again, this is a matter for a fire risk assessment by a competent fire risk assessor, who will consider fire risk holistically, taking into account various factors, such as the location of the fire door, the other fire precautions in the building and the occupancy of the building. 

Application of guidance

All guidance on fire safety in buildings contains recommendations for the fire resistance of fire doors. 

Typically, in guidance that supports building regulations (e.g. in England and Wales, Approved Document B) a period of 30 minutes’ fire resistance is recommended for fire doors that protect means of escape, while 60 minutes’ fire resistance is recommended in certain situations (e.g. firefighting shafts).

In certain locations, a minimum period of 20 minutes’ fire resistance is recommended (e.g. for fire doors subdividing corridors or located within a dwellinghouse).  However, in practice, 20 minute fire doors are not readily available, so normally fire doors of 30 minutes’ fire resistance are used.

Because of changes in the fire resistance test standard over a number of decades, for a timber fire door to achieve 30 minutes’ fire resistance, there is a need for the door to be fitted with intumescent strips.  Older fire doors that met original standards may not be fitted with intumescent strips, so will not achieve 30 minutes’ fire resistance.  Whether or not this justifies upgrading needs to be determined by a competent fire risk assessor.

In the case of doors that protect escape routes, guidance specifies protection against the passage of smoke at ambient temperature, necessitating the provision of smoke seals.  Again, older fire doors may not be fitted with smoke seals, and, again, whether they should be fitted retrospectively needs to be determined by a competent fire risk assessor.

There is no rigorous science or engineering that underlies the period of 30 minutes’ fire resistance.  It is based on the recommendations of a committee of experts in the 1950s, who publicly acknowledged that it was not based on data, but was something of a best guess that would incorporate a reasonable factor of safety.

This further amplifies the point that small departures from the period of 30 minutes’ fire resistance may have little effect on fire risk, which is a matter for the judgement of a competent fire risk assessor, according to the circumstances in question. 

At one extreme, in the case of a care home with disabled residents and few staff on duty at night, in the absence of sprinkler protection, prolonged tenability of escape corridors might be necessary, so making the fire resistance of room doors particularly important. 

At the other extreme, in an office building with protection by sprinklers and automatic fire detection, a fire door between a corridor and a stairway is most unlikely to be exposed to a fire with the severity of the standard test furnace, so the fire resistance of the door is less critical, though it must be reasonable in the circumstances.

Appropriate guidance

All of the above discussion is recognized in government guidance that supports fire safety legislation for existing buildings.  While government guidance that supports building regulations is appropriate for new buildings, different government guidance applies to existing buildings.

The guidance for existing buildings is not intended to be prescriptive, but simply provides recommendations that are benchmarks against which an existing building can be judged.  It should be understood that what is necessary for compliance with fire legislation may be less (or more) than is described in the benchmarks.

By way of example, it is known that there are many complaints by leaseholders regarding a requirement to replace flat entrance doors, simply because they do not comply with current standards or are not certificated as such; as noted earlier, certification is not necessary for compliance with legislation.

More significantly, guidance that was originally published by the Local Government Association, and that is now made available by government on the gov.uk website[2], recognizes the principle of notional FD30 doors, which are defined as “door assemblies that satisfied the current specification, or fire resistance test, for 30 minutes at time of construction of a block of flats or manufacture of the door”.

These doors will not be fitted with intumescent strips or smoke seals and are likely to afford no more than 20 minutes’ fire resistance.  The guidance advises that, in most circumstances, these doors will continue to be satisfactory unless there is a need for doors of greater fire performance to compensate for departures of other measures from the guidance.

The Fire Safety (England) Regulations

While these Regulations are prescriptive, they do not specify the required performance of flat entrance doors, nor do the checks of flat entrance doors specified in the Regulations require the services of specialists.  The checks can often be carried out by, for example, a caretaker. 

The Regulations were brought in to satisfy the recommendations of Phase 1 of the Public Inquiry into the Grenfell Tower fire.  One recommendation was that flat entrance doors should be regularly checked to ensure that they are self-closing. 

This is reflected in Regulation 10(4) of the Fire Safety (England) Regulations, which requires that the Responsible Person make best endeavours to check flat entrance doors in blocks of flats over 11 m in height at periods not exceeding 12 months.   (Checks are also required of doors in common parts every three months.) 

Guidance on the Regulations[3] makes it abundantly clear that these checks are only to confirm that the doors are self-closing, that the doors are undamaged and that any intumescent strips or smoke seals are undamaged. 

More specifically, the guidance advises that:

“It is not intended that these checks should involve any more detail, technical examination of the doors, or of the original standard of installation, nor is it intended that these checks need to be carried out by specialists.  It is expected that the Responsible Person, or their staff, should, with simple instruction, be able to carry out the checks.”