Fire Doors Explained

Fire doors are an engineered fire safety device that play a critical role in the passive fire protection of every commercial, public and multiple-occupancy building as they provide resistance to the spread of fire and smoke and protect escape routes, thereby protecting property and saving lives.

A fire door is required to provide two primary functions within a building:

• To maintain any compartmentation of the building which has been introduced to limit the size and spread of fire in order to control the perceived level of risk.
• To allow access to protected escape routes, both vertically and horizontally, without any loss of fire resistance, and limit smoke movement in the structure forming these routes, i.e. protected corridors and protected shafts.

After evacuation, fire doors should continue to provide some protection for firefighters entering the building to extinguish the fire.

The Sum of its Parts

Fire resistance is a property that can be possessed by only a complete construction, and not by the individual components or materials from which the construction is formed. Appendix B of TGD B of the Building Regulations states that a fire door is the sum of its parts in the following definition:

“Any reference to a fire door in this Technical Guidance Document, or in any code of practice or other document referred to in this Technical Guidance Document, is intended to mean a complete door assembly which includes the door leaf or leaves, the door frame, ironmongery (hinges, latches, closers, etc.) and any seals where required between the frame and leaf or between leaves in the case of a twin-leaf door, and which is installed in a building and is capable of meeting the required performance. The performance of a fire door critically depends on the correct installation of the complete door assembly, strictly in accordance with the terms of the relevant test certification supplied by the door manufacturer.”

In the case of a fire door, it is only the complete assembly as described in the relevant fire test report that can be deemed to provide the required performance. All of the components have to work together to ensure that the door assembly will work as tested in the event of a fire. All additional components, seals and ironmongery must be compatible with the door configuration as confirmed by test evidence. Therefore, a door leaf, door frame, building hardware or any other component part cannot be fire-resisting in isolation from its other parts.

Critically, if any of the individual components from which the fire door is constructed is defective or if the installation is not in strict accordance with the manufacturer’s recommendations, the complete fire door assembly cannot be relied on to perform as intended in a fire situation.

Testing & Certification of a Fire Door

Fire resistance is proven through destructive fire testing and by expert assessment. Manufacturers submit their products to a UKAS accredited test facility, such as BM TRADA or BWF-CERTIFIRE, who then subject the complete fire door assembly or doorset to a destructive fire test.

The Test

Since a fire door assembly is only valid for use in the configuration in which it is tested, the test specimen must be representative of the configuration in which it is intended to be used.

The fire resistance of a door assembly is determined by subjecting a full-size construction to a destructive test in accordance with the procedures laid down in the appropriate fire resistance testing standard, i.e. BS 476-22 or BS EN 1634-1. The test standard requires the tested construction to be fully representative of the assembly to be used in practice in terms of materials and methods of construction, size, number of leaves and mode of operation including all glazed openings and essential building hardware. Specifically, the specimen and supporting construction is built into a 3m x 3m restraint frame which is mounted on the front of a furnace.

The fire resistance is expressed in terms of the number of minutes for which the assembly meets the relevant criteria. Depending upon the test standard used for the evaluation, the criteria would be one or all of the following: stability, integrity, insulation. For the purposes of classification, doors are classified to the last specific fire resistance period that has been passed during the test before failure occurs.

The Fire Rating

The method of expressing the results of fire resistance tests, both at international and national levels, only utilizes the criteria of integrity (E) and insulation (I). The performance of a fire door when tested in accordance with BS 476-22 or BS EN 1634-1 is judged by its time to failure (in minutes) for both integrity and insulation. However, for the purposes of regulatory guidance, fire doors are designated by reference to their required performance for integrity. Such doors are identified by the prefix FD followed by the required integrity rating expressed in minutes, e.g. FD30, a fire-resisting door able to resist integrity failure for 30 minutes. Typical fire door ratings are FD20, FD30, FD45, FD60, FD90 and FD120.

In a fire safety strategy it might be an additional requirement for a door to meet the criteria of insulation (I) and/or radiation (W) for a specified period of time.

In addition to the need to provide fire resistance, certain doors are also required, by legislation, to restrict the spread of ambient temperature (“cold”) smoke. These doors are identified by the suffix S, e.g. FD30S, and, when tested in accordance with BS EN 1634-3 or BS 476-31.1, are required to conform to BS EN 13501-2 or to the relevant part of BS 5588, respectively.

NOTE 1: National building regulations only apply to life safety. Higher performance levels (such as insulation) might be necessary for certain applications if property protection is required.
NOTE 2: Insulation (I) and radiation (W) performances are totally different. Ratings for glasses should only be compared on the basis of fire test results.

The Test Report

Once a door has been tested, a report will be issued that will contain all the construction details of the tested specimen, together with information on the size and configuration of the test sample. The test report itself is a purely factual document, stating the results of the testing. Other relevant information such as observations taken by the test engineers, graphs showing furnace and specimen temperatures and distortions (if applicable) will also be contained within the final test report. Most importantly, a door that has successfully passed the test will then be given a certified fire rating indicating the period of proven fire resistance.

A test report is a statement of fact - no more and no less. Test reports only relate to what has been tested and allow little in the way of variations. Any changes to a construction tested under the British or European standards will either require another fire test, or an assessment.

Assessment

An assessment is a statement of opinion that is based on factual reports. It is a desktop study by an experienced fire consultant that allows both engineering expertise and the experience accumulated from other tests to be added to the facts of a particular test.

Clause 4 of BS 8214 provides the following comment:

“When it is impossible, due to size or other constraints, or is impractical, to evaluate the constructions by a full-scale destructive test then it is appropriate to have the potential fire resistance of the construction determined by way of agreed expert opinion based on existing test evidence. This course of action might be required when evidence of performance of a particular component has been established in connection with another form of construction. As a successful fire resistance performance is often the result of complex interactions between materials it should never be assumed that a result obtained under one set of circumstances will be conferred on a different combination of components or materials. It might be possible, however, for the proposed combination to be determined as suitable by a competent expert, on the basis of evidence generated in other tests.”

In all cases, the assessment can only extrapolate or extend primary test evidence established in respect of a particular door leaf construction.

Global Assessment

Every fire door should be supported by a test report from a UKAS accredited testing facility which indicates that the complete assembly will meet the required performance. The testing facility will issue a test report detailing the test results, which is a purely factual document. The report can be further expanded upon by an expert assessment in the form of a Global Assessment to expand the range of options available to the door manufacturer and specifier.

A global assessment can bring together the results of multiple tests and provide a scope based upon all of the evidence. Once the test programme has been completed (and all results are successful), the accredited test facility will write a global assessment report that will bring together all the various items of test data into a single document. This document will clearly explain the full scope of the product to the end-user.

As the constituent parts of a fire door often interact in quite subtle ways, any changes from the original tested specification can significantly alter the performance of the assembly installed. A global assessment allows variations from a tested design using documentary evidence from other test reports to support the variation, thereby negating the need to conduct a separate test for each variation.

A Project Specific Assessment tailored to meet the needs of a specific project can also be produced.

Fire Door Label

Traceability of the fire door leaf is critically important. Clause 5 of BS 8214 recommends that all fire doors should bear a label showing, as a minimum provision, the manufacturer’s name, the fire rating of the door, and a traceable serial number.

TGD B of the Building Regulations (2006) has the following requirement:

“All fire doors installed in a building should be permanently identified in accordance with the recommendations of BS 8214, to indicate the period of fire resistance, the manufacturer, year of manufacture, and other pertinent details. Every fire door (i.e. the complete fire door assembly) should be supported by a fire test report and assessment from an accredited laboratory, which indicates that the complete assembly will meet the required performance.”

A fire door that cannot be linked to a test report and assessment from an accredited test laboratory also cannot be proven to have been tested to the required period of fire resistance as required by the Building Regulations. It also cannot be shown to be “supported by a fire test report and assessment from an accredited laboratory” as is also required by the Building Regulations, and therefore the local fire authority may demand that all unverified doors should be replaced with verified fire doors.

Fire Rated Glazing

Fire Rated Glass Type & Applicable EN Standard:


Clause 5 of BS 8214 states:

“Fire-resisting glass should be identified with an appropriate designation. The mark on the glass should be permanent, legible and visible after glazing, including as a minimum the glass manufacturer's name, the product name and impact rating if required. Accompanying documentation should provide specification information for the glass, including the performance classification and applicable test or certification references. “

Any glass that cannot be proven to have the required period of fire resistance should be replaced.

Route to Compliance with Building Regulations

B7 of Appendix B of TGD B of the Building Regulations¹ states that all fire doors must be tested by an accredited² testing laboratory³ to either BS 476-22 or I.S. EN 1634-1.

“Every fire door (i.e. the complete fire door assembly) should be supported by a fire test report and assessment from an accredited laboratory, which indicates that the complete assembly will meet the required performance.”

There are therefore two routes to compliance:

• A fire test report
• An assessment

A fire test report is a statement of fact and therefore only applies to exactly what has been tested by the accredited testing laboratory. An assessment, however, is a statement of expert opinion based on observed test performance. It allows both engineering expertise and the experience accumulated from other tests to be added to the facts of a particular test.

¹ The Regulations are not retrospective. The Building Control Act 1990 and the Building Regulations/ Building Control Regulations came into effect on 1 June 1992.
² The United Kingdom Accreditation Service (UKAS) is the sole national accreditation body recognised by the British government to assess the competence of organisations that provide certification, testing, inspection and calibration services.
³ Typically BM TRADA or BWF-CERTIFIRE.