GB2536139A

GB2536139A - Fire retardant device

Info

Publication number: GB2536139A
Application number: GB1604883.7A
Authority: GB
Inventors: Jarvis William
Original assignee: METFLAM Ltd
Current assignee: METFLAM Ltd
Priority date: 2010-05-04
Filing date: 2010-06-18
Publication date: 2016-09-07
Anticipated expiration: 2030-06-18
Also published as: GB2536139B; GB2480114B; GB2480114A; GB201007407D0; GB201604883D0; GB201010465D0

Abstract

A fire retardant transom or fire retardant mullion 80 for a door or window frame includes two elongate members 86, 88 having transversally projecting portions 82. It further includes an impeding feature, preferably a hole 84, acting as a thermal break between the elongate members. The projecting portions are arranged to form a channel for receiving intumescent material 46, 72, 76, 90 from either or both of the impeding feature and the portion of the door corresponding to the transom or mullion. The arrangement is such that the intumescent material is abutted by the projecting portions so that opening, bowing or dishing of the door or window is resisted.

Description

FIRE RETARDANT DEVICE

This invention relates to fire retardant devices arid in particular, but not exclusively, to fire retardant glazed windows and doors and frames and components therefor.

The walls and inner fire-zone partitions of modern buildings are generally fabricated using materials that are known to impede the spread of fire. However, weak points in the resistance to fire may occur at the locations of apertures in the walls or partitions. For example, fire may take less time to traverse a closed window or door than it would to traverse a solid wall. Accordingly, many jurisdictions have buildings regulations that set out fire performance requirements for newly installed windows, doors, and partitions. In the United Kingdom, doors and windows that are installed in regulated building zones must comply with a given fire resistance as determined in accordance with British Standard 476: part 22: 1987 "Methods for determination of the fire resistance of non-load bearing elements of construction" and/or BS EN 1364-1:1999 "Fire resistance tests for non-loadbearing elements", the whole contents of both of which are hereby incorporated by reference.

British Standard 476 sets out methods for assessing both the integrity and the insulating properties of doors and windows when subjected to fire. Window and door integrity during a fire is important for preventing the direct spread of fire, and the insulating properties of a window or door are important during a fire both for preventing any materials that are adjacent to the door or window from reaching their ignition point, and for sheltering any people that may be behind the door or window. Integrity and insulating performance for a given door or window may be given in terms of a time value, for example, under test conditions a specific door may have met the required integrity criteria for 30 minutes but have only met the required insulating criteria for 20 minutes.

For apertures that are specified to have a translucent or transparent filling, such as windows or glass doors, special glazed materials that have fire retardant properties generally need to be used in order for the door or window to comply with buildings regulations. An example product that incorporates such materials is the Securiglass (registered trade mark) product supplied by C3S Securiglass From a fire resistance perspective, the interface between a fire retardant glazed pane and its surround is a potential a point of weakness and may cause reduced performance with respect to the pane and/or aperture surround or may necessitate bulky additional door or window furniture to avoid reduced performance. For example, the stiles of glazed fire retardant doors are typically 70 to 90mm wide which can limit the glazed surface area that is available for the passage of light and may also be unaesthetic According to one aspect, there is provided a fire retardant glazing device such as a door, window, partition, or surround, frame, or component therefor. The device comprises a bridging or spine portion having a pair or retaining elements -one on either side of the spine -the retaining elements being arranged to form a channel for a glazed product and the device further comprising one or more impeding elements, such as holes, positioned to reduce thermal conduction across the spine.

Advantageously the impeding elements impede thermal conduction across a glazed product having such a device, thereby increasing the fire insulating properties of the product when installed in an aperture In a preferred embodiment, the impeding elements are holes and thermally intumescent material is located adjacent to the holes. Although the presence of holes on their own would enable the circulation of convection currents, thereby deleteriously effecting the insulating properties of the device, the presence of the intumescent material means that, upon exposure to heat beyond the activation temperature of the intumescent material, the intumescent material expands to fill the holes thereby impeding the circulation of convention currents In a preferred embodiment, the device further comprises a second a pair of retaining elements -one on either side of the spine -the second pair of retaining elements being arranged to form a channel for one or more intumescent units. Preferably such a device is a component part of a door stile. Advantageously, such a device may be relatively thin, for example 15mm across.

According to one aspect, there is provided a fire retardant transom (or mullion) for a door frame, the transom (or mullion) comprising a pair of elongate elements each having a transversally projecting portion, the projecting portions being arranged to form a channel in which to receive activated intumescent material from a door stile (or head) when the door is closed and subjected to heat above the activation temperature of the intumescent material. The transom (or mullion) further comprising one or more impeding elements, preferably holes, arranged to impede thermal conduction between the elongate elements.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a diagrammatic representation of example apertures that the devices described herein may be employed with; Figure 2 shows a perspective view of a glazing surround portion; Figure 3 shows a plan view of the glazing surround of Figure 2; Figure 4 shows an end view of the glazing surround of Figure 2; Figure 5 shows a cross-sectional view of the glazing surround of Figure 2; Figure 6 shows a cross-section through a glazing surround portion attached to a wall and a glazed pane; Figure 7 shows the cross-section of Figure 6 following intumescent material activation, Figure 8 shows a perspective view of a glazed door, Figure 9 shows a close up perspective view of a portion of the glazed door of Figure 8; Figure 10 shows a perspective view of a portion of an intumescent unit holding member; Figure 11 shows a plan view of the member of Figure 10 Figure 12 shows an end view of the member of Figure 10; Figure 13 shows a cross-sectional view of the member of Figure 10; Figure 14 shows a cross-sectional view of an intumescent unit holding member and a glazing surround portion attached to a glazed pane; Figure 15 the cross-section of Figure 14 following intumescent material activation; Figure 16 shows a cross section through a door end and associated mullion trim; and Figure 17 shows a cross section through a door end and associated transom.

With reference to the drawings in general, it will be appreciated that the Figures are not to scale and that, for example, relative dimensions may have been altered in the interest of clarity in the drawings.

Figure 1 shows a diagrammatic representation of a wall having a number of different apertures in which the devices described herein may to employed. For example, the devices described herein may be employed with a lone glazed door 12 (or frame therefor), or a pair of glazed doors 14, 16 (or a frame therefor) that do not have an intermediate door frame element that lies between the doors when they are closed and may have one or more side lights 18, 20 and/or a top light 22. The devices described herein may also be employed in a window 24 or for one or more glazed partitions 26, 28 and frames therefor.

Glazing Surround Figure 2 shows a perspective view of a glazing surround 30 as may be coupled to or integral with a window, partition, sidelight, toplight, or frame therefor. The glazing surround 30 comprises a spine or bridging portion 32 and a pair of projecting or retaining portions 34, 36 that are coupled to the bridging portion 32 and project therefrom to form a channel into which a portion of a glazed pane or panel may be inserted for holding the pane in place -for example as in a shuffle glazed system. The glazing surround also comprises one or more holes 38 positioned in the bridging portion 32 so as to reduce the ability of the bridging portion 32 to conduct heat from one retaining portion 34 to the other retaining portion 36.

Figure 3 shows a plan view of the glazing surround 30 of Figure 2 and Figure 4 shows an end view of the glazing surround 30 from line A-A of Figure 3, Figure 5 shows a cross sectional view through the glazing surround 30 of Figure 3 along line B-B; as can in seen, in this case, the hole 38 is a through hole through the bridging portion 32. Advantageously, the holes 38 in the bridging portion 32 reduce conduction from one retaining portion 34 to the other retaining portion 36 thereby increasing the insulating properties of the glazing surround when installed in a building and subjected to heat from one side of any glazed pane held by the glazing surround 30.

Figure 6 shows a cross section through the glazing surround 30 of Figure 2 when installed against a window frame 40 and retaining a glazed pane 42. In this example, positioned between the glazing surround 30 and the window frame 40 is a first strip of intumescent material 44, for example a graphite or ammonium phosphate based intumescent material, that is activatable by heat to cause the intumescent material to expand. A person skilled in the art will recognise other intumescent materials that may alternatively or additionally be employed. There is also a second strip of intumescent material 46 positioned between the glazing surround 30 and the glazed pane. To avoid over complicating Figure 6, the fixation devices for fixing the glazing surround 30 to the window frame 40 and for holding the glazed pane 42 in position with respect to the glazing surround 30 have not been shown. Preferably, the glazing surround 30 is fixed to the window frame 40 by one or more bolts or screws (not shown) positioned in between the holes 38 and one or both of the retaining portions 34, 36 and preferably the glazed pane 42 is held in position with respect to the glazing surround 30 by one or more beads of heat resistant sealant; a person skilled in the art will understand other conventional manners in which the glazing surround 30 may be attached respectively to the window frame 40 and glazed pane 42.

Figure 7 shows the cross section of Figure 6 following the application of sufficient heat to activate the intumescent strips 44, 46. As can be seen, the heat has activated the intumescent strips 44, 46 which have expanded to substantially fill the hole 38 in the bridging portion 32 The intumescent strips have also expanded to substantially fill both the gap in between the frame 40 and the bridging portion and the gap in between the glazed pane 42 and the channel formed by the pair of retaining portions 34, 36 and the bridging portion.

As the intumescent strips 44, 46 themselves have thermal insulating properties, their activation helps to reduce heat transfer during a fire from a first side of the glazed pane (referenced as C in Figure 7) to a second side of the glazed pane (referenced as D in Figure 7). In particular, upon activation the material from one or both of the intumescent strips 44, 46 may enter the hole 38 in the bridging portion thereby removing or reducing any air gap that may have been present in the hole 38 and further increasing thermal insulation. The use of an intumescent strip to further improve the insulating properties of the glazing surround 30 during a fire advantageously avoids the need to accurately machine, cut, fit, press, or otherwise incorporate an insulating component into the glazing surround 30 Although Figures 6 and 7 show the glazing surround 30 installed with intumescent strips 44, 46 on both sides of the bridging portion 32, in other embodiments, one or both of the intumescent strips 44, 46 may be omitted.

Door Stile and Transom Figure 8 shows a perspective view of a door 48, the door comprising a glazed pane 50, respective top and bottom bars 52, 54, and a pair of stiles 56, 58. Figure 9 shows a zoomed in perspective view of the bottom left hand corner of the door 48 of Figure 8 in the region delimited by the phantom lines of Figure 8. To enable visualisation of holes 68 in a component of the door stile 60, a strip of intumescent material that would otherwise be present has been omitted from Figure 9.

Figure 10 shows a perspective view of a door stile component 60 as may be coupled to a glazed door. The door stile component 60 comprises a spine or bridging portion 62 and a pair of projecting or retaining portions 64, 66 that are coupled to the bridging portion 62 and project therefrom to form a channel for one or more intumescent units, such as an extruded component having a filing of intumescent material and one or more openings to allow activated intumescent material to expand through, or an intumescent strip, such as a strip of intumescent tape. A person skilled in the art will recognise other intumescent units that may be employed with the door stile component 60 described herein. The door stile component 60 also comprises one or more holes 68 positioned in the bridging portion 62 so as to reduce the ability of the bridging portion 62 to conduct heat from one retaining portion 64 to the other retaining portion 66.

Figure 11 shows a plan view of the door stile component 60 of Figure 10 and Figure 12 shows an end view of the door stile component 60 from line E-E of Figure 11. Figure 5 shows a cross sectional view through the door stile component 60 of Figure 11 along line F-F, in this case, the hole 68 is a through hole through the bridging portion 62. In this embodiment, the retaining portions 64, 66 comprise a bend to facilitate retention of the one or more intumescent units and, when the intumescent material is activated by heat, intumescent material.

Advantageously, the holes 68 in the bridging portion 62 reduce conduction from one retaining portion 64 to the other retaining portion 66 thereby increasing the insulating properties of the door stile component 60 when installed in a door and subjected to heat from one side.

Figure 14 shows a cross section through a door stile component 60 and a glazing surround 30 when the respective bridging portions 32, 62 thereof are coupled back to back to form a door stile 58. A person skilled in the art will recognise a number of ways in which door stile component 60 and glazing surround 30 may be coupled, for example, they may be screwed, bolted, or welded together, and/or may be integral. Accordingly, instead of having two bridging portions 32, 62, there may only be a single bridging portion coupled to the retaining portions 34, 36, 64, 66. Preferably, the bridging portions 32, 62 are positioned so that the holes 38, 68 therein are aligned.

As in the example shown in Figure 6, the glazing surround 30 of Figure 14 retains a glazed pane 50 which, in this example, forms the body of the door 48 and has a strip of intumescent material 44 interposed between the glazed pane 50 and the channel formed by the bridging portion 32 and the glazing surround's retaining portions 34, 36. The channel formed by door stile component's bridging portion 62 and its retaining portions 64, 66 contains intumescent units 70, in this example the intumescent units 70 are extruded strips filled with intumescent material 72 and having openings 74 to allow, upon activation, the intumescent material 72 to expand therethrough, the channel also contains an intumescent strip 76 interposed between the intumescent units 70 and the door stile component's bridging portion 62 Figure 14 shows door 48 adjacent to a door frame 78. In this example, the door 48 is a two way door -the door can be opened both inwards and outwards -and has a mullion 80 coupled to the door frame 78. In this example, the mullion is profiled to have projecting portions 82; when the door 48 is held in its closed position adjacent to the door frame 78 and subjected to heat to activate the intumescent units 70, the projecting portions 82 of the mullion 80 abut the expanded intumescent material 72 of the intumescent units 70 and help hold the door in place and resist opening, bowing or dishing of the door 48 due to Lire, The mullion 80 also comprises one or more holes 84 positioned in the mullion 80 so as to reduce the ability of the mullion 80 to conduct heat from one side of the mullion 86 to the other side of the mullion 88, this helps to reduce thermal bridging between the two sides of the mullion 86, 88 in the event of a fire In this example, the hole 84 contains an intumescent material 90 for filling the hole 84 and/or the gap between the mullion 80 and the door 48 during a fire Figure 15 shows the door 48 and mullion 80 of Figure 14 following activation of the intumescent material 46, 72, 76, 90 by heat. As can be seen, the heat has activated the intumescent strips 46, 76 which have expanded to substantially fill the holes 38, 68 in the bridging portions 32, 62. The intumescent material 46, 72, 76, 90 has also expanded to substantially fill: the channel formed by the door stile component's bridging and retaining portions 62, 64, 66; the gap between the mullion 80 and the door 48; and the hole 84 in the mullion 80 The thermal insulating properties of the expanded intumescent materials 46, 72, 76, 90 help to reduce heat transfer during a fire from a first side of the closed door 48 (referenced as Gin Figure 15) to a second side of the closed door (referenced as H in Figure 15). In particular, the expanded intumescent material 46, 72, 76, 90: i) insulates a middle portion of the mullion 80 by substantially filling the hole 84 thereby reducing heat transfer from one side 86 of the mullion to the other side 88; ii) substantially fills holes 38, 68 thereby reducing heat transfer from side G of the door stile component 60 and the glazing surround 30 to side H thereof; and iii) substantially fills the gap between the mullion 80 and the door 48 thereby reducing heat transfer through the gap The expanded intumescent material in the gap between the mullion 80 and the door 48 also interacts with the projecting portions 82 of the mullion 80 to impede opening, bowing or dishing of the door due to forces exerted upon the door due to the fire.

Modifications and Variations Figure 16 shows an alternative embodiment of the glazing surround 92, door stile component 94 arid mullion trim 96 As can be seen, the mullion 96 is fixed to a wall 98 by a pair of screws 100 and has a channel 102 in which is located a strip of intumescent H material 104. The mullion 96 also has a brush seal 106 to impede gaseous movement between the two sides of the glazed door 108. The glazing surround 92 has a channel that contains intumescent material 110 and a glazed pane 112. The door stile component 94 forms a channel that contains a strip of intumescent material 114 and an intumescent unit 116 that contains two different types of intumescent material 118, 120 (one of which has been selected for its insulating properties and the other of which has been selected for its pressure sealing properties).

A person skilled in the art will appreciate that, whilst the above has been described with reference to the vertical part of a door aperture surround (a mullion), the same approach could equally be applied to the horizontal part of a door aperture surround (a transom) and that accordingly, approaches described herein with reference to a mullion may equally be applied to a transom. For example, in Figure 17 a transom 120 is fixed to a wall 122 by a pair of screws 124 and has a channel 126 in which is located a strip of intumescent material 128. The transom HO also has a brush seal HO to impede gaseous movement between the two sides of a glazed door 132. The glazed door has at its top a door head component 134 having intumescent material 136, 138.

A person skilled in the art will appreciate that instead of fixing the mullion or transom to a wall, the transom may instead be fixed to proprietary aperture framing system.

A person skilled in the art will appreciate that each of the above described door stile and mullion may be employable individually, for example, the above described mullion may be employed with a known door stile, and the above described door stile may be employed with a known mullion or door frame. A person skilled in the art will also appreciate that a door stile having a door stile component 60 and a glazing surround 30 as described herein need not have all of the intumescent materials described herein; for example, one or both strips of intumescent material 46, 76 may not be present and/or the one or more intumescent units 70 may not be present. Furthermore, a person skilled in the art will appreciate that different types of intumescent material may be employed alone or in combination, for example, where more than one intumescent material is employed, a first one or more of the materials may be a thermally insulating material whilst a second one or more materials may be arranged to form a pressure resistant seal.

As one possibility, instead of having holes, one or more of the glazing surround 30, the door stile component 60, and/or the mullion 80 may have one or more impeding elements arranged to impede thermal conduction by having inferior heat conduction properties to that of the glazing surround 30, the door stile component 60 and/or the mullion 80 (which is generally of a thermally conductive material, for example the bridging portion may be of a metal such as steel, for example folded 2mm thick sheet steel), for example such an impeding element may comprise an insulating material such as ceramic wadding. A person skilled in the art will have no difficulty in identifying insulating materials that could be employed as impeding elements. As one possibility, the impeding element may be integral with the glazing surround 30, the door stile component 60 and/or the mullion 80 As one possibility, one or more impeding elements may be staggered with respect to a long axis of the glazing surround 30, the door stile component 60, and/or the mullion 80, thereby forcing heat conducting across the glazing surround 30, the door stile component 60, and/or the mullion 80 to take a circuitous route A person skilled in the art will appreciate that the retaining portions of the door stile component described above need not have bends in them and may instead be straight or curved.

A person skilled in the art will appreciate that although a door stile is described above, the component parts of such stiles may be made and sold independently and so that description should not be taken to be limiting.

A person skilled in the art will appreciate that, although the above has described through holes in the glazing surround 30, the door stile component 60, and the mullion 80, the holes may instead be blind holes.

A person skilled in the art will appreciate that the glazed panes referred to herein need not be planar and instead may be curved or irregular. The person skilled in the art will further appreciate the references herein to glazed panes, glazing, etc., refer not only to glass products, but also to transparent or translucent plastic products and to other transparent or translucent materials. Preferably glazed panes as described herein are fire retardant, for example, they may be made from the Securiglass (registered trade mark) product supplied by C3S Securiglass. As another possibility, instead of a glazed pane, the apparatus described herein may be employed with an opaque pane or panel, such as a fire retardant panel or a decorative panel.

A person skilled in the art will appreciate that the holes in the glazing surround 30, the door stile component 60, and/or the mullion 80 may be formed by the removal of material form an original blank or from the creation from component parts of the glazing surround 30, the door stile component 60, and/or the mullion 80. For example, the mullion 80 may be formed by attaching, for example by welding, transverse bridging strips to a pair of longitudinally oriented strips to form a ladder like mullion.

As one possibility, the holes in the glazing surround 30, the door stile component 60, and/or the mullion 80 have curved edges, advantageously, this can reduce both localised stress and hot spots Preferably the glazing surround, the door stile component, and the mullion described herein are arranged to meet the insulation requirements of British Standard 476: part 22: 1987 "Methods for determination of the fire resistance of non-load bearing elements of construction" for a period of 70 or more minutes.

As one possibility, instead of the above described glazing surround being arranged for fixation to a wall or window, the glazing surround may have third and fourth retaining portions arranged to retain a second glazed pane; in this manner, the glazing surround may be used in situations where a plurality of end-to-end glazed panes are employed A person skilled in the art will appreciate that, although the above has described channels for glazing panes and intumescent units with respect to Figures having generally u-shaped channels, the channels may have other shapes, for example, they may be v-shaped, c-shaped, w-shaped, or have a stepped profile. Likewise, the above described mullion may be arranged to have a u-shaped, v-shaped, c-shaped, w-shaped, etc. profile.

A person skilled in the art will appreciate that although the term glazing surround has been employed herein, it should not be construed to require that any glazed pane held be the surround be completely surrounded; instead, such glazing surrounds may surround one or more portions of such panes.

A person skilled in the art will appreciate that, whilst the above has described a mullion having one or more holes, as another possibility, the mullion could instead be split into two or more separate pieces -for example, one piece for each side of the door.

A person skilled in the art will appreciate that references herein to intumescent materials and/or strips refer to intumescent materials and strips that are activatable by the application of heat.

Various features described above may have advantages with or without other features described above The above embodiments are to be understood as illustrative examples of the invention.

Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Alternative Embodiments Alternative embodiments of the present invention are also defined by way of the following clauses: Clause 1. A fire retardant glazing device comprising: a bridging portion a first retaining portion coupled to a first side of the bridging portion; and a second retaining portion coupled to a second side of the bridging portion; wherein: the first and second retaining portions and the bridging portion are arranged to form a channel for a glazed pane; and the bridging portion comprises at least one impeding element arranged to impede thermal conduction between the first and second sides of the bridging portion.

Clause 2 The device of clause 1, wherein the first and second retaining portions and the bridging portion are unitary, Clause 3. The device of clause 1, further comprising: a third retaining portion coupled to the first side of the bridging portion; and a fourth retaining portion coupled to the second side of the bridging portion, wherein the third and fourth retaining portions and the bridging portion are arranged to form a channel for one or more intumescent units.

Clause 4. The device of clause 3, wherein the first and second retaining portions and a first portion of the bridging portion are unitary, and the third and fourth retaining portions and a second portion of the bridging portion are unitary.

Clause 5. The device of clause 3 or 4, further comprising a strip of intumescent material arranged so that, when one or more intumescent units are received in the channel for or more intumescent units and the strip is activated by heat, one or more portions of the activated strip lie between the one or more intumescent units and the bridging portion.

Clause 6. The device of clause 5 wherein at least one of the at least one impeding elements is a hole in the bridging portion, preferably a through hole, and wherein the strip of intumescent material is further arranged so that, when one or more intumescent units are received in the channel for one or more intumescent units and the strip is activated by heat, intumescent material from the activated strip enters the hole.

Clause 7. The device of any preceding clause, further comprising a strip of intumescent material arranged so that, when a glazed pane is received in the channel for a glazed pane and the strip is activated by heat, one or more portions of the activated strip lie between the glazed pane and the bridging portion.

Clause 8. The device of clause 7 wherein at least one of the at least one impeding elements is a hole in the bridging portion, preferably a through hole, and wherein the strip of intumescent material is further arranged so that, when a glazed pane is received in the channel for a glazed pane and the strip is activated by heat, intumescent material from the activated strip enters the hole.

Clause 9. The device of any of clauses 1 to 5 or 7, wherein at least one of the at least one impeding elements is a hole in the bridging portion, preferably a through hole.

Clause 10. The device of any preceding clause, wherein at least one of the at least one impeding elements is an insert of fire retardant, insulating and/or intumescent material.

Clause 11. The device of any preceding clause, having a plurality of said impeding elements, wherein said impeding elements are staggered with respect to a transverse axis of the channel for a glazed pane Clause 12. The device of any preceding clause wherein the bridging portion is made of a thermally conductive material, preferably of a metal, and more preferably of steel.

Clause 13. A window, window frame, door, or door stile comprising the device of any preceding clause, preferably wherein the window, window frame, door, or door stile is able to meet the insulation requirements of at least one of British Standard 476: part 22: 1987 "Methods for determination of the fire resistance of non-load bearing elements of construction" and BS EN 1364-1:1999 "Fire resistance tests for non-loadbearing elements" for a period of 30, 60, or 90 or more minutes, preferably for 70 minutes or more.

Clause 14 A fire retardant glazing device substantially as described herein and with reference to the accompanying drawings.

Clause 15. A fire retardant transom or fire retardant mullion for an elongate portion of a door frame, the transom comprising: a first elongate member having a transversally projecting portion; a second elongate member having a transversally projecting portion; wherein the projecting portions of the first and second elongate members are arranged to form, when coupled to a door frame, a channel for receiving activated intumescent material from a door portion, the transom or mullion further comprising at least one impeding element arranged to impede thermal conduction between the first and second elongate members.

Clause 16. The transom or mullion of clause 15, wherein at least one of the at least one impeding elements is a hole in the transom or mullion Clause 17. The transom or mullion of clause 16, further comprising heat activatable intumescent material in the hole.

Clause 18. A door frame comprising the transom or mullion of any of clauses 15 to 17.

Clause 19 A fire retardant transom or fire retardant mullion substantially as described herein and with reference to the accompanying drawings.

Claims

C LA I MSI. A fire retardant transom or fire retardant mullion for an elongate portion of a door or window frame, the transom or mullion comprising: a first elongate member having a transversally projecting portion; a second elongate member having a transversally projecting portion; and at least one impeding arranged to impede thermal conduction between the first and second elongate members, wherein the projecting portions of the first and second elongate members are arranged to form, when coupled to a door frame, a channel for receiving and to receive heat-activated intumescent material from at least one of the at least impeding feature and the portion of the door or window, such that the heat-activated intumescent material, when received in the channel, is abutted by the projecting portions of the transom or mullion to resist opening, bowing or dishing of the door or window due to the heat; and at least one impeding feature arranged to impede thermal conduction between the first and second elongate members.
2. The transom or mullion of claim 1, wherein at least one of the at least one impeding features is a hole in the transom or mullion.
3. The transom or mullion of claim 2, further comprising heat activatable intumescent material in the hole.A door frame comprising the transom or mullion of any of claims 1 to 3 Amendment to the claims have been filed as follows: CLAIMS I. A fire retardant transom or fire retardant mullion for an elongate portion of a door or window frame, the transom or mullion comprising: a first elongate member having a transversally projecting portion; a second elongate member having a transversally projecting portion; wherein the projecting portions of the first and second elongate members are arranged to receive: a one piece surround comprising a first retaining portion, a second retaining portion and a bridging portion; wherein the first and second retaining portions and the bridging portion are arranged to form a channel to receive a first intumescent material and to support a pane, and wherein the bridging portion has one or more holes.2 The transom or mullion of claim 1, wherein the surround is configured to be to CO 15 receive a second intumescent material between the surround and the first and second elongate members CD 3. The transom or mullion of claims 1 or 2, wherein the one or more holes are elongate.
4. The transom or mullion any preceding claim, wherein the one or more holes extend along the surround.
5. The transom or mullion any preceding claim, further comprising an intumescent material and wherein the intumescent material comprises a strip of intumescent material extending along the surround.
6. The transom or mullion any preceding claim; further comprising a pane and wherein the pane configured to be held in position with respect to the surround by one or more beads of heat resistant sealant.The transom or mullion of claim 6, wherein the pane is a glass pane.A door frame comprising the transom or mullion of any of claims 1 to 7 9. A kit of parts comprising a fire retardant transom or fire retardant mullion according to any preceding claim and the first intumescent material received in the channel.10. A fire retardant transom or fire retardant mullion substantially as described herein and with reference to the accompanying Figures 6 and
7.