What is a fire door?
A fire-resisting door or fire door is provided to resist the passage of fire, smoke and heat for a significant period, usually 30 minutes or 60 minutes so that the occupants of a building can safely evacuate the building. In holding back fire and smoke, escape routes are maintained and fire spread within the building is resisted. Any door in a fire resisting wall or partition must be a fire door.
A fire-resisting door or fire door means a door, or pair of doors, tested in accordance with British Standard BS 476-22 or BS EN 1634-1, that satisfies the requirements of that test, when fitted in its frame as to resisting collapse for not less than an hour and resisting the passage of flame for not less than 20 minutes, but with no minimum period as to insulation.
Fire doors, other than those to locked cupboards or service ducts, are normally fitted with door closers.
Fire doors should be purpose designed and manufactured doors and frames. When upgrading the structural fire protection of existing buildings, it is usual to install new certified fire doors that incorporate the latest technology and will perform consistently in the event of a fire.
Upgrading existing doors to achieve a reasonable fire resistance
There are few occasions that it is desirable or necessary to retain existing doors, but increase their fire resistance. These occasions are usually to do with a building of historic interest, where the doors and frames may be of substantial construction and need little modification to bring them up to the required level of performance.
Where existing timber doors are of the panelled type, with stiles and rails not less than 44mm thick, they may be protected to the required standard if the face of the panels is entirely covered on the room or risk side of the door with a minimum of 6mm of an approved fire resisting board e.g. Masterboard or Supalux fitted flush with the framing of the door. The edge of the fire resistant board should be covered with hardwood beading, with both board and beading nailed at 40mm centres.
If the thickness of the rails and stiles is less than 44mm but more than 37mm, the face of the panels may be covered with a fire resisting board at least 6mm thick, fixed securely using 32mm x No.8 wood screws at 300 centres around the perimeter of the door. Additional fixings to centre lines or rails are recommended. In the case of Masterboard and Supalux, see the manufacturers fixing instructions.
Existing flush timber doors of substantial construction may be retained if the entire face of the door on the room or risk side is covered with a fire resisting board of at least 6mm thickness and securely fixed as mentioned above.
There are now intumescent veneers available such as Sealmaster Fireface which when used on suitable doors in accordance with the manufacturers instructions will upgrade the fire resistance of an existing timber door to a reasonable fire resistance.
Where a material used to upgrade the fire resistance other than Supalux, Masterboard or Sealmaster Fireface is used, details of the material, manufacturers instructions and appropriate fire test certification shall be submitted to justify the proposed material and method of upgrading the fire resistance of the doors in question.
Existing hardboard or other lightweight doors are not considered adequate or suitable for upgrading. They should be replaced by doors of at least FD20 standard.
Other points to bear in mind
Hinges must be capable of taking the increased weight of the door.
Plastic and low melting point hinges are not suitable. Door ironmongery other than hinges should also be fire resisting.
Fire doors other than those to locked cupboards and service cupboards normally need to be self-closing. Self-closing devices should be of a type, which can not be easily removed or tampered with, which will completely close a door, and overcome the resistance of a latch fitted, from fully open or partially open position.
An intumescent seal should be fitted across the head of the door and down the sides of the door. Alternatively the seal can be fitted in the door frame. There is normally a gap of 2-4mm between door and frame.
Where doors are required for means of escape purposes, the provision of a brush or blade smoke strip to resist the passage of smoke may also be required. When smoke strips are fitted, a gap wider than 4mm may be needed between door and frame.
A threshold is not required under a fire door. However, it is advisable to avoid flammable floor coverings running uninterrupted under a door. A metal carpet-edging strip will achieve a firebreak.
Any glazing in a fire door, in a fanlight over a fire door or in a fire resisting wall or partition must be fire resisting. The glazing must be suitably framed so that the assembly achieves not less than the minimum required period of fire resistance for the element the glazed door, fanlight or glazed panel is fitted in.
Additional information may be obtained from the BRE and Timber Research and Development (TRADA).
This information was correct at the time of writing (October 2007).
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Building Control
Environment and Regeneration
Waltham Forest Council
Sycamore House
Forest Road
London E17 4JF
Tel 020 8496 3000
Email building.control@walthamforest.gov.uk
