What fire doors do
Fire safety guidance issued by the government includes a checklist of five key steps, which includes the need to identify escape routes in premises and the relevant fire safety equipment.
Fire doors are vital in fire safety offering protection of the escape route from fire in adjacent rooms and by compartmentalising sections of escape routes or building segments.
What a fire door is
The Architectural and Specialist Door Manufacturers Association (ASDMA) defines a fire door as follows: 'A complete installed door assembly comprising door frame, door leaves, other panels, hardware, seals and any glazing that when closed is intended to resist the passage of fire and smoke in accordance with specified performance criteria. A fire door = a complete installed assembly.'
Where fire doors are needed
There are two main requirements of fire doors which dictate their location in a building.
As part of a system, fire doors:
- compartmentalise a fire
- and create or protect an escape route through the building.
Fire doors must not impede the normal use of the building.
Retainers can be used to keep them legally open, although the doors should be regularly closed as part of their routine maintenance to prevent warping or other malfunctions that could compromise their integrity in a fire.
These should release the door upon activation of the fire alarm and warning system.
How long can a fire door be effective?
The function of a fire door, when closed, is to provide resistance to smoke and/or fire for a minimum specified length of time. Typically, this is 30 minutes with a certified fire door of timber construction (FD30).
It is possible to have steel fire doors offering up to four hours’ resistance but this level of protection is usually only a requirement in specific, high-risk environments. Thirty minutes should, in most situations, allow for the evacuation of premises and response of the Fire and Rescue Service.
Upgrading to a fire door
Can existing doors be upgraded to fire resistant standard?
Because of the specialist nature of fire doors, it is always advisable to fit them from new which is often the most cost-effective option as well.
An upgrade to FD30 status is sometimes possible, however, depending on the construction of the existing door, especially if it is part of an historic building. It should be of solid timber or chipboard, at least 44mm thick, and with a sound frame that is capable of bearing the additional weight of the upgraded door. The gap between the door and the frame should be 2 to 4mm.
An unpainted door can be painted with intumescent varnish or paint, to manufacturer/supplier specifications. A painted door can be covered with an intumescent membrane with fireproof card/wood veneer facing, which is more aesthetically pleasing than plain, non-combustible board. If glazed, the glass panel(s) must be replaced with fire rated glass.
The upgraded door must be re-hung with at least three fire protected hinges, to prevent warping. The integrity of a fire door will be severely compromised if it should warp, as it will no longer fit snugly in its frame. All other hardware e.g. locks, latches, etc. must be similarly upgraded to fire resistant standard. Other modifications, including the addition of intumescent seals, will also be necessary, as indicated in the section above concerning the various parts of a fire door assembly. Some surface mounted fire door seals allow an upgrade without having to cut out a channel in the door to fit the seals.
Certification of a fire door
Manufacturers “off the peg” or bespoke/customized fire doors can have their products 3rd-party certified, thereby guaranteeing the level of fire resistance. The standard test of a fire door set is to BS 476 Pt 22 or BS EN 1634-1.
The integrity of a fire door refers to its resistance to fire over time; if rated FD30, for example, it will give at least 30 minutes of protection; FD60, an hour’s protection; and so on.
This is the rating system applied by the British Woodworking Federation (BWF) under their Certifier Fire Door and Door set Scheme. Each door set supplied to scheme specifications carries a permanent and tamper evident label.
Although certification is not necessary, and a fire risk assessor may consider a nominal (i.e. uncertified) fire door as capable of holding back a fire for a specified length of time, 3rd-party certification ensures that the products used in the manufacture and supply of fire doors are fit for purpose.
Installation of a fire door
The ASDMA definition of a fire door as a “complete installed assembly” highlights the fact that the installation - and maintenance - of a fire door set is as important as the products used in its construction.
As such, although a competent professional can install a fire door, it is recommended that the work be carried out under the auspices of the Accredited Fire Door Installers Scheme. Developed by the BWF in association with FIRAS, the purpose of this scheme is to ensure that fire door installations are carried out correctly, safely and in compliance with current Building Regulations.