FIRE-RESISTING DOOR ASSEMBLY

Transcription

1 1. Introduction HMO Information Sheet No 2 FIRE-RESISTING DOOR ASSEMBLY In the event of a fire, it is normal practice to evacuate a property via the main escape route. The main escape route is normally along the landing and down the stairs and out through the front door to a place of safety. Action should be taken to ensure that, in the event of a fire, occupants have enough time to safely exit a property. Effective fire-resisting door assemblies are vital to ensure that the occupants can evacuate to a place of safety. Correctly specified and well-fitted doors and frames will hold back fire and smoke and will prevent escape routes from becoming unusable, as well as preventing the fire spreading from one area of the property to another, until the emergency services arrive. A fire-resisting door assembly is necessary in any doorway that opens onto the emergency escape route. Most internal doors in a property are constructed of timber and whilst they give some limited protection against fire spread, it is only a purpose-built fire-resisting door assembly, tested to an approved standard that will provide the necessary protection. In order to assess sufficient protection of the escape route, it is important to consider whether the standard of fire resistance and surface finishing in the escape routes is satisfactory, if it has been affected by wear and tear and alterations and whether any improvements are necessary. This fact sheet will detail the components of a fire door assembly in a House of Multiple Occupation (HMO), as one measure to ensure the occupants have sufficient time to exit a property in the event of a fire. For the purposes of this fact sheet it is assumed that any reference to a fireresisting door is to one of wooden construction. The use of fire doors made of alternative materials would require further specific advice. 2. What is a Fire-Resisting Door Assembly? A purpose-built fire-resisting door assembly can be obtained from a specialist manufacturer and is installed by a competent person. This is the fire-resisting door combined with the doorframe. The installer will provide a certificate detailing the level of fire resistance that has been achieved i.e. 30 minutes. The significant findings of your fire risk assessment will determine those doors within the property that need to be fire-resisting door assemblies. Normally in a HMO, any habitable room, or high-risk area, opening directly onto the escape route will need to have a fire-resisting door assembly installed. The level of fire 1

2 resistance the door should provide will depend on the presence of a suitable and sufficient automatic fire detection and alarm system in place, as per Fact Sheet 1. However if a LD2 Grade A or D AFD system is present (depending on the size of HMO) the fire-resisting door assembly can be rated to give 30-minutes fire resistance. Otherwise a 60-minute fire-resisting door may be necessary e.g. a cellar door - where there is no AFD in the cellar and thus no early detection to raise the alarm in the event of a fire. The lack of early detection of a fire but the increased fire resistance of the door assembly would still provide sufficient time to retain the spread of fire and ensure the occupants can evacuate to safety. A typical 30-minute fire-resisting door assembly consists of the following: 30 minute fire-resisting door and frame Self-closing devices Cold smoke seal and intumescent heat seal Door furniture 3. Components of a 30-minute Fire-Resisting Door Assembly The fire-resisting door and frame should be purchased as a complete set thus ensuring the satisfactory fit of the door in the frame and the installation will provide the necessary 30-minute fire resistance. This can be verified by the certification that accompanies the door set, if installed as per the manufacturers instructions. The main components included in a 30-minute fire-resisting door assembly covered by this fact sheet are included in Figure 1 below. 2

3 Figure 1 Components of a 30-Minute Fire-Resisting Door Assembly This fact sheet will cover the specification and installation of the individual components of a fire door assembly as follows: A - Fire-Resisting Doors All fire-resisting doors are rated by their performance when tested to an appropriate standard. The level of protection provided by the door is measured, primarily by determining the time taken for a fire to breach the integrity of the door assembly, together with its resistance to the passage of hot gases and flame. The rule of thumb is a 30-minute fire-resisting door is 45mm thick and a 60- minute fire-resisting door is 54mm thick. This does not necessarily apply but the majority of fire doors still fall within these categories. Timber fire-resisting doors require a gap of 2-4mm between the door leaf and the frame. The gap between the fire-resisting door and the finished threshold must be kept to a minimum, and must not exceed 10mm. Where the gap exceeds 10mm, or the floor is out of level, a hardwood threshold must be fitted. It is important to consider the size of door opening when preparing a scheme. A standard fire-resisting door can only be trimmed within the limits specified by the 3

4 manufacturer. Where there is a non-standard door opening it will be necessary to use solid door blanks cut to the appropriate size and then hardwood door lippings applied to the edges. 30-minute fire-resisting doors can be obtained in the following formats: (i) (ii) Door Blanks solid timber Framed Leaves FD30 half hour fire door to BS 476 Part 22 with intumescent heat seals. FD30S half hour fire door to BS 476 Part 22 with intumescent heat and cold smoke seals. Every BWF-CERTIFIRE Fire Door Assembly carries a permanent and tamper evident label. For more information go to their web site [see below]. 4

5 Upgrading Existing Doors In the past doors were routinely upgraded into fire doors, lining the door panels with fire resisting sheeting and fitting large doorstops. Previously upgraded doors are very unlikely to meet the required specification unless the paperwork is available to confirm the extent of work carried out and the degree of fire resistance achieved. In addition cold smoke seals and intumescent heat seals still need to be fitted. Upgraded doors that are damaged or a poor fit to the frame will not be accepted under any circumstances. In some circumstances, such as where a property is a listed building, the replacement of doors with fire doors may not be an option. In such cases the door must first be examined by a specialist contractor to assess its suitability. Some doors will be in too poor a condition, or not thick enough to make upgrade possible, in which case alternatives will need to be considered. Guidance on how to improve the fire resistance of existing timber doors can be found in: Increasing the Fire Resistance of Existing Timber Doors, Information Paper 8/82, Building Research Establishment (BRE). Glazing Glazing can only be fitted to doors, which are designed for the purpose and tested to the relevant BS. The doors are often sold without the glazing panel and glazing must be fitted in accordance with manufacturer s instructions. Any plain glazing should be replaced by, or backed with, 6mm wire reinforced glass or equivalent, not exceeding 1.2m 2 in area and fitted with solid wood beading not less than 13mm in cross section. If you install a door with glazing, you will be required to demonstrate that it has been installed in accordance with the manufacturers instructions. B - Fire-Resisting Door Frames In all circumstances the fire-resisting door and frame should be installed as a complete set. Where the door and frame cannot be installed as a complete set the following information provides advice on how to upgrade the existing doorframe: In all openings where a fire door is fitted, or is to be fitted, the existing linings and architraves must be thoroughly checked to determine whether or not they provide sufficient fire resistance. In particular, consider the following: If the existing frame is in poor condition or warped so that it will be difficult to achieve a proper, close fit and good smoke seal for the fire door, then a new fire-resisting frame will be required. In many cases this will be more cost/time effective than trying to patch up an old frame. 5

6 If the existing frame is to be retained it must be capable of supporting the additional weight of the new fire door, and must be of sound, welljointed timber. If new timbers are to be added to the frame to improve the fit of the door, they must be glued and screwed to the existing linings. If the existing architraves do not provide an adequate seal with the wall they must be removed on the risk side (i.e. the room side) and all gaps between the door lining, wall/partitioning and non risk side architrave must be filled and sealed with fire-resisting materials e.g. 12.5mm plasterboard with skim finish or intumescent paste. Suitable architraves must be re-fitted to the risk side. The original architraves may be reused if they are in sound condition. All new architraves must be a minimum of 15mm thick and 45mm wide. Doorstops The doorstops on the existing frame are likely to be 12mm or less and are inadequate when the doorframe is being upgraded. These have to be removed and replaced by 25mm stops so the doorframe has a rebate or stop not less than 25mm wide and 38mm long glued and screwed to the existing doorframe at 300mm centres. Guidance on how to improve the fire resistance of frames can be found in: Fire Resisting Doorsets by Upgrading, Wood Information Sheet 1-32, Timber Research and Development Association (TRADA). C - Self-Closing Devices Self-closing devices fitted to fire-resisting doors must be positive in action and capable of closing and latching the door and holding it firmly against the rebates of the frame. Rising butt hinges and garden gate type coil springs do not meet the specification and are not acceptable due to their inability to close and latch the door. Overhead hydraulic closers are recommended as being the most effective and reliable type, allowing the door to close in a controlled manner. Chain spring closer (Perco) can be used as an alternative; however, the chain closer does not control the closing speed of the door, thus causing the door to slam. It is recommended that you fit self-closing devices that are easily adjustable. D - Cold Smoke Seal and Intumescent Heat Seal The cold smoke seal and intumescent heat seal (IHS) is ideally fitted to the doorframe or alternatively rebated into the two vertical and top horizontal edges of the fire-resisting door. The intumescent heat seal and cold smoke seal can be 6

7 fitted as combined unit. See Figure 2 - which details examples of the positioning of intumescent heat seals and cold smoke seals. The cold smoke seal (which consists of small brush hairs or flexible blades) acts initially to prevent smoke escaping through the closed door. If the fire develops the heat will cause the IHS to expand and hold the door in the frame to give 30- minutes fire resistance. Perimeter smoke seals that are fitted to the door stops so that the door closes against them are not usually accepted. Where appropriate they may be accepted when upgrading a door in a listed building, where it is often difficult to get a smoke seal on the edge of the door to form an adequate seal with a lining. No intumescent material must be fitted to the front face of the door or to the doorframe against the front face of the door. This is because in the event of a fire the intumescent material will expand and force the door open. All door furniture i.e. hinges, locks and latches should be bedded in intumescent putty/paste to ensure continuity of the intumescent seal to prevent any weakness of the fire door assembly at these weak points. The seals must be fitted in accordance with the manufacturers instructions. CLOSE ATTENTION MUST BE GIVEN TO THE GAP BETWEEN THE DOOR AND FRAME. As a guide it should not be more than 2-4mm. A larger gap may render the intumescent seal ineffective in a fire. In addition, you must ensure that if a door edge mounted smoke seal is being used it brushes right up against the door lining. It is important that you do not paint or varnish over the cold smoke seal when decorating the door as this will render it ineffective. 7

8 Figure 2 Position of Intumescent Heat and Cold Smoke Seals Combined intumescent heat and cold smoke seal (brush type) fitted in door leaf. Combined intumescent heat and cold smoke seal (flexible blade) fitted in door leaf. Perimeter cold smoke seal fitted to doorstop and intumescent heat seal fitted in door leaf. E Door Furniture Hinges Fire-resisting doors must be hung on 1 1/ 2 pairs (i.e. 3 hinges) of 100mm pressed steel butt hinges. The central hinge should be approximately 500mm down from the top of the door i.e. closer to the top hinge than the bottom hinge. Brass hinges cannot be used. Latches Latches have an important role in ensuring the integrity of the fire-resisting door; a door must be fitted with a handle and latch. The latch is the only holding device on the closing edge, hence it is important that it should be strong and that the nib of the latch should engage into the latch plate at least 12mm to ensure that the closing edge will not spring open when the door deforms. After the edges, the latch areas represent the next zone of weakness. Filling the voids in the cut-out section with intumescent paste will markedly lessen the weakness in this area. 8

9 Locking Arrangements Where a lock is to be fitted to the fire-resisting door it must be of the type that allows the door to be held shut but which does not lock unless a key is used on the outside, such as a thumb turn opening on the inside. The door, whether locked or not, must be openable from inside the room without the use of a key. A cylinder rim dead lock with roller bolt is recommended e.g. Yale 81 or Union 1158 or the Euro Mortice Lock with thumb turn. Other locks may be acceptable, providing they meet the same specification. Additional bolts, chains etc, must not be fitted by the landlord or tenant. Any provision made for increased security must not compromise the means of escape of the occupants. Any redundant door furniture should be removed and the pockets filled with timber bedded in intumescent material. Apertures in Fire-Resisting Doors Generally the fitting of standard letterboxes, door viewers, cat flaps, etc, will undermine the effectiveness of a fire door. It is possible to get products that will protect the integrity of the door and which meet the relevant BS but the specification for installation must be closely followed. 4. Certification of a Fire-Resisting Door Assembly The installer will provide a certificate detailing the level of fire resistance that has been achieved i.e. 30 minutes. A copy of the certificate must be forwarded to Private Sector Housing, Deene House, Corby Borough. Council, New Post Office Square, Corby, Northamptonshire, NN17 1GD 5. Maintenance of a Fire-Resisting Door Assembly The fire-resisting door assembly must be regularly checked to ensure that all the component parts are in place and working correctly. The fire-resisting door must close securely to the latch without the use of force. This document has been produced by Corby Borough Council and provides a guide to a Fire-resisting Door Assembly for HMOs. For specific advice please contact the Private Sector Housing Team on