Fire doors are tested and certified as complete doorsets (door leaf, frame, ironmongery, seals, and glazing) not as individual components. Therefore, the resistance rating on the certification label only applies when the door is installed as the tested assembly, in the configuration and with the components listed in that certification. Using a different hinge, seal, or closer cancels the test evidence, even if the door leaf is unchanged.
Testing is done according to BS EN 1634-1, which sets out the methods for testing fire resistance and smoke control of door sets. The results determine the rating applicable to the doorset.
How Resistance Ratings Work
The FD prefix stands for Fire Door. The number that follows denotes the number of minutes of fire resistance offered under standard test conditions. More specifically, the number indicates the duration for which the doorset inhibits the passage of flame and hot gases, in accordance with the standard time-temperature curve defined in BS EN 1363-1.
The commonly used ratings for commercial and industrial premises are as follows:
FD30 — 30 Minutes The minimum specification for internal compartment doors in many commercial buildings. FD30 is the regulatory standard for doors between a stairwell and a corridor, between the office and the common area, and at most compartment boundaries in a routine fire risk assessment. The majority of fire doors fitted in offices, retail, and light industrial buildings are FD30.
FD60 — 60 Minutes Specified where the fire risk assessment shows that 30 minutes of protection is insufficient — usually at boundaries next to high fire load zones, (fire) plant room(s), electrical intake room(s), and protected stair(s) in big or high-rise buildings. FD60 is also standard for the door between a (built in) garage and a domestic house, but that is beyond the commercial scope of this site.
FD90 and FD120 — 90 and 120 minutes Required in high-risk industrial scenarios, at interface zones of buildings with notably disparate fire risks, and in fire-engineered scenarios where the structural fire resistance of the building necessitates prolonged compartmentation. FD90 and FD120 doorsets are regarded as specialist products and are considerably more massive than FD30 or FD60 — frame construction and structural fixings needs to be designed accordingly.
The risks associated with fire are not a matter of choice or cost. It is a consequence of the fire risk assessment, which should be prepared by a professional. If a fire engineer has provided a fire strategy for the building, then the door ratings specified in that strategy must be adhered to.
The S Suffix — Smoke Control
The S designation — FD30S, FD60S — means that the doorset is dual certified for smoke and fire, i.e. smoke control is included along with fire resistance. S-rated doors are fitted with intumescent seals which expand when heated to close the gap between the door and frame, and combined with cold smoke seals that obstruct smoke flow at room temperature prior to the intumescent activation.
Most fire-related deaths occur due to smoke inhalation, not due to burns or injuries from flames. Victims bleed from the eyes and mouth due to lack of oxygen and/or loss of consciousness long before the flames reach their target. In that case, an occupant’s flow through the door might not be protected to the extent that the door provides the passage. A door may be expected to provide excellent passage protection, but if the perimeter joints of the door allow smoke to escape, the occupants may be more at risk than the door has rated protection.
The fire risk assessment states whether or not smoke control at a particular fire door is needed. Therefore, the S rated door is the standard specification at most commercial buildings, especially along escape routes, in horizontal escape corridors serving sleeping areas, and in any position where the threat of smoke movement between rooms is above acceptable levels.
Most new commercial buildings have an FD30S door as default, which is now the standard guidance provided in BS 9999 (British Standard fire safety code) for most compartment door locations.
Types of Fire Door Construction
The type of construction used to make a fire door and the protection afforded to that door by the fire door’s resistance rating are two different things.
Solid core timber doorsets are the most commonly used type for commercial buildings. Fire resistance comes from core materials that include mineral fibre, calcium silicate board and engineered timber composite. The outer veneers are considered non-structural. Solid core doors are available for most ratings, making them suitable for most office, retail and light industrial uses.
Steel doorsets are used when fire resistance with physical security, forced-entry resistance, or the toughness needed for high-traffic industrial areas is required. Steel doorsets have the same fire ratings as timber counterparts and are often used for plant rooms, electrical intake rooms, external fire exit doors, and compartment doors in warehouses. They are much more heavy and require stronger frames and fixings.
Glazed fire doorsets are fully certified doorsets with fire-rated glazing units that could be intumescent glass, or glass that has a transparent intumescent interlayer. The glazing area, unlike standard float glass which has no fire resistance and cannot be used, has to be certified to be equal or higher than the doorsets resistance rating. Glazed doorsets are used often in office spaces for corridor safety vision panels, and in high-end commercial spaces when safety and fire resistance aesthetics are a consideration.
Timber-framed glazed screens and fire doors are not the same as glazed doorsets and therefore require separate certifications for the screens and the doors. If a fire door is placed within a larger glazed screen, the screen must also be certified for fire resistance to the same level as the door, and the joint detail between the door frame and screen must be shown to be tested.
Certification Marks
Each fire door must have a permanent mark of compliance. This is in the form of a plug label located on the top edge of the door leaf and details the door manufacturer, certification body, fire resistance rating, and a unique certification number. This label is the evidence of compliance. Doors without labels, fire doors with damaged labels, and doors with labels that have been painted over are not able to be considered compliant without a full investigation.
BWF-CERTIFIRE and Certifire (Warringtonfire) are the two main third party certification schemes in the UK. They both have publicly accessible registers, and therefore, installers and facilities managers may check that the certification of a doorset is up to date and that the specific product supplied is within the certified parameters.