Fire Resisting Self Closing Doors

Transcription

1 Background This Note f Inspecting Officers provides guidance on the standards that are considered appropriate in respect to Fire Resisting Self-Closing Dos. The Note aims to set general principles and to provide the reader with infmation as to which approved document technical standard is considered by this Authity to be appropriate. Further infmation on the testing and assessment of fire resisting metal do sets (e.g. dos with swinging leaves) can be found in FS-NFG028 Fire Resisting Metal Dos. Definition of Fire Do The expression "fire do", "fire do assembly" and "fire do set" are synonymous f the purposes of this Note f Guidance and have the following definition: "A do shutter provided f the passage of persons, air things which, together with its frame and furniture as installed in a building, is intended when closed, to resist the passage of fire and/ gaseous products of combustion and is capable of meeting perfmance criteria to these ends". Functions of Fire Dos Fire dos have at least one of two functions to perfm and, in certain situations both i.e. 1. To protect escape routes from the effects of fire so that occupants can safely reach a final exit; and 2. To protect the contents and/ structure of a building by limiting the spread of fire. Consequently any particular fire do may have to perfm one both of these functions f the purposes of smoke control, protecting means of escape, compartmentation the segregation of special risk areas. Perfmance of Fire Dos Fire Protection Fire Resisting Self Closing Dos Issue/Revision Date 01/10/2010 Review Date 15/12/2016 Version 8.0 Procedure & Guidance Ref FS- NFG003 Fire Dos f Smoke Control Fire dos provided f smoke control purposes should be capable of withstanding smoke at medium temperatures Smoke control fire dos are provided f life safety purposes and play an imptant role in the vicinity of the fire in its early stages and in protecting escape routes me remote from a fully developed fire. Although smoke control dos are not required to meet any specific period of fire resistance, they should be of substantial construction. Flexible edge seals should be provided f the early control of smoke movement. Tests have shown that do stops (rebates) that have been increased to 25mm do not improve the smoke stopping perfmance of dos because a fire do will bow towards the fireexposed side. Page 1 of 7

2 Fire Dos to Protect Means of Escape Fire Dos provided to protect means of escape should be capable of achieving a minimum fire resistance f integrity of 30 minutes, when tested in accdance with an appropriate British, European International standard. The dos are required to keep escape routes sufficiently free from smoke long enough to allow occupants to reach a place of safety and to maintain integrity against the effects of fire long enough to fulfil that objective. To achieve this they may need smoke seals. NB: When other methods of smoke control are provided in buildings, e.g. pressurisation of escape routes, the ability of fire dos to withstand smoke may not be applicable. Fire Dos f Compartmentation and the Segregation of Special Risks Fire Dos provided f fire compartmentation and the segregation of special risk areas must be capable of achieving the period of fire resistance appropriate to the structure which is not less than 30 minutes and may be as much as 6 hours. To achieve this level of fire resistance, it may be necessary to provide two fire dos in series. The sum total of the fire resistance would be designed to meet the required standard. If such dos are also required to protect an escape route they will need also to have the smoke control capabilities described above. In some circumstances e.g. the protection of property, it may be necessary f them to be capable of withstanding high temperature smoke. Increasing the Fire Resistance of Existing Timber Dos Increasing the fire resistance of existing dos is not nmally acceptable and usually it will be me cost effective to install a new do. However, in certain instances it may be necessary to retain an existing do e.g. in a listed building and, where the reasons are considered valid by an enfcing authity it may be appropriate to modify the dos to provide an improved standard of fire resistance. Guidance on how to improve the fire resistance of existing timber dos can be found in: - Building Research Establishment Infmation Paper 8/82 "Increasing the fire resistance of existing timber dos" and the Timber Research and Development Association's Wood Infmation Sheet, Section 1, Sheet 32, "Fire Resisting Do sets by Upgrading". Fire Safety - Public Advice Note FS-PAN0025 "Dos - Upgrading the Fire Resistance of Existing Dos". NB: An existing timber do nmally can only have its fire resistance improved to a maximum of 30 minutes Designation of Fire Dos Fire dos should be designated by the initials FD followed by the perfmance in minutes that the do should achieve when tested in accdance with British Standard BS476: part 22 f integrity of not less than 30 minutes (i.e. 30 minutes fire resistance). Where the do should also resist the passage of smoke at ambient temperatures the suffix "S" should be added to the designation. Two illustrations of this are as follows; 1. The entrance do to a flat in a block of flats would be required to protect the means of escape, so that the crect designation would be FD 30s. 2. A fire do is a 60 minute compartment wall where there are no means of escape considerations would be designated FD 60. Page 2 of 7

3 Marking Of Fire Dos Table 1 All fire dos should be permanently marked with their designation (as above). A convenient and recommended method is by use of a colourcoded plug, inserted in the edge of the hanging stile, and confming to the table given on the right. Ce Colour Background colour Integrity Mins Colour Interpretation Code Red White 20 Intumescent seals Yellow 30 require to be fitted at the time of iginal Pink 45 installation Blue 60 Brown 90 Black 120 Green White 20 No additional Yellow 30 intumescent seals need to be fitted at Pink 45 the time of installation Blue 60 Brown 90 Black 120 Blue White 20 With no intumescent seals fitted. White 30 With intumescent seals fitted in either do edge frame Intumescent and Smoke Seals F do assemblies designed to achieve 20 min 30 min integrity, test experience shows that a 10mm wide strip of intumescent material which has satisfied the test described in BS476: Part 23 f the relevant period, fitted centrally into the leaf frame rebate of a conventional sized, latched, single leaf, single swing assembly will nmally be adequate. The seal strip may be interrupted at ironmongery positions. F similar dos designed to provide periods of 60 minutes fire resistance greater, the intumescent seal specification will be at least twice that required f 30 min applications and with at least part of the seal by-passing all ironmongery fixings. F double leaf assemblies the quantity of intumescent seal will be that established by test and will be dependent upon the behaviour of the do leaves. Where separate smoke and intumescent seals are to be fitted, they should be placed with one in the do leaf and one in the frame. Compression type smoke seals should be used on latched dos only (Blade and brush types do not rely on latches). Page 3 of 7

4 Frame to wall junction The junction between a do frame and wall should be dealt with in accdance with tables 2 and 3. Fit of do leaf Leaf to frame gaps should not exceed those as tested to BS 476: Part 22. Gaps exceeding 4mm are not likely to be acceptable even when intumescent material is present. Smoke seals should make continuous contact. Gaps should allow f some settlement and shrinkage. Threshold sealing Intumescent sealing is not nmally necessary and gaps of up to 8mm can nmally be tolerated. If the gap exceeds 3mm and total smoke control is required, a seal must be provided. Glazing apertures Apertures f glazing any other purpose should be provided by the manufacturer. Evidence of manufacturer's approval would nmally be required f post fming of apertures. (See Letter-plates below). Glass and glazing beads should be in accdance with the manufacturer's specifications. Timber beads are likely to be suitable only if of substantial dimensions and in conjunction with intumescent bedding mastics. See also FS-NFG014 Fire Resisting Glass". Maintenance Fire and Smoke Seals should be examined at six monthly intervals and replaced if necessary. Do gaps should be examined at the same time and should receive attention if they have increased to me than 5mm become so tight as to over compress the smoke seals. Replacement of glazing should be in accdance with manufacturer's recommendations. Hardware should be appropriately lubricated. Replacement of hardware should be with identical components, ones approved by the manufacturer and any gaps resulting should be filled with suitable intumescent material. Self-closing devices and latches should be checked at six monthly intervals to ensure they are wking fully and effectively. Self Closing Devices A fire do (except to a cupboard service duct) should nmally be fitted with a self closing device (other than rising butt hinges) that: 1. Should be of a type that cannot readily be disconnected immobilised and does not embody a stand-open action; 2. Should override any latches fitted to the do(s); in the absence of a suitable latch other positive device f holding the do shut in its frame, should be of a type that has been shown by test to be capable of holding the do closed in the frame f a sufficient period of time f the closing role to be taken over by a thermally activated sealing device (such as an intumescent seal), throughout the full period of exposure if such seals are not incpated. Page 4 of 7

5 Letter-plates (Letterboxes) The provision of letter-plates in fire resisting dos should be avoided where possible and approval should be obtained from any enfcing authity befe they are installed. Letter-plates are not acceptable in any do required to give a fire resistance greater than 30 minutes. An acceptable alternative to the provision of letter-plates is separate mail boxes that can be protected me easily from the effects of fire. The following criteria should apply befe the Fire Authity will consider giving approval f the provision of a letter-plate in a fire-resisting do: - 1. The do must be of suitable construction and the aperture cut in the do must be in an area of solid timber. 2. The size of the aperture cut in the do must not exceed the size of that in the letter-plate. 3. The letter-plate should be sited 900mm up from the flo as this is where the neutral pressure axis is expected to be in a fire situation. 4. The letter-plate must be constructed from metal and have a positive spring closer fitted to it. 5. A stainless steel inner flap with a positive spring closer must be provided. It should have a generous overlap which must not be less than 10mm and it must be independently screwed to the do and not be reliant on the bolt fixings from the back of the letter-plate to hold it in position. 6. A combined smoke and intumescent seal must be provided around the aperture cut in the do and the inner flap must close onto this seal. Notices Fire dos should be marked "FIRE DOOR - KEEP SHUT" on each face unless it is a do to a ste room, service duct etc, in which case it should be marked "FIRE DOOR KEEP LOCKED" on the outer face. The size, shape and colouring of the notice should comply with BS 5499: Part 1: 1990, Appendix B.3 "Mandaty Signs". Page 5 of 7

6 Table 2 RECOMMENDATIONS FOR THE JOINT BETWEEN TIMBER DOOR FRAMES AND WALLS TO PROVIDE 30 MIN FIRE RESISTANCE Wall Construction Maximum Frame to Wall Gap Width Architrave Condition Additional Protection Non-load bearing walls unlikely to exhibit significant disttion during fire exposure e.g. timber stud walls and masonry walls without fair face > Load bearing walls likely to exhibit disttion during fie exposure e.g. steel stud walls > Load bearing nonload bearing walls. Fair faced masonry walls > Up to 10mm > Me than 10mm > All gap sizes > Me than 10mm > Up to 10mm > Intimately fitted soft of hard wood architraves at least 15mm thick with a 15 mm overlap onto the wall and do frame > Imperfectly fitting architraves > All architrave conditions > Fit of architrave cannot be guaranteed due to likely disttion of the wall > All architrave conditions > Immediately fitted 19mm hardwood quadrant bead > Nil 2mm x 10 mm of intumescent material as a pre-fmed strip seal mineral glass wool packed to a depth of at least 10mm A bed of intumescent mastic Nil NOTE: There is a risk that wall finishes with a surface spread of flame rating of Class 3, as defined in BS476:Part 7, may contribute to ignition and flaming of the architrave on the unexposed face due to leakage of hot gases. F smoke control do sets frame to wall gaps should always be packed with mineral glass wool sealed with a bead of intumescent paste mastic. Page 6 of 7

7 Table 3 RECOMMENDATIONS FOR THE JOINT BETWEEN TIMBER DOOR FRAMES AND WALLS TO PROVIDE 60 MIN FIRE RESISTANCE Wall construction Non-load bearing walls unlikely to exhibit significant disttion during fire exposure e.g. timber stud walls and masonry walls without fair face > Load bearing walls likely to exhibit during fire exposure e.g. steel stud walls > Load bearing nonload bearing walls. Fair faced masonry walls > Maximum Frame to Wall Gap Width Up to 10mm > Me than 10mm > All Gap sizes > All Gap sizes > Architrave Condition Intimately fitted soft hard wood architraves at least 15mm thick with a 15mm overlap onto the wall and do frame > Imperfectly fitting architraves > All architrave conditions > Fit of architrave cannot be guaranteed due to likely disttion of the wall > All architrave conditions > Additional Protection 2mm x 10mm of intumescent material as a pre-fmed stop seal mineral glass wool packed to a depth of at least 10mm A bead of intumescent mastic 2mm x 20mm of intumescent material as a pre-fmed strip seal mineral glass wool packed to a depth of at least 10mm A bead of intumescent mastic NOTE: There is a risk that wall finishes with a surface spread of flame rating of Class 3, as defined in BS476:Part 7, may contribute to ignition and flaming of the architrave on the unexposed face due to leakage of hot gases. F smoke control do sets frame to wall gaps should always be packed with mineral glass wool sealed with a bead of intumescent paste mastic. Page 7 of 7