GB2444772A

GB2444772A - Fire resistant door

Info

Publication number: GB2444772A
Application number: GB0624824A
Authority: GB
Inventors: Nigel Taylor; Robert Hoellrigl
Original assignee: Bowater Building Products Ltd
Current assignee: Bowater Building Products Ltd
Priority date: 2006-12-13
Filing date: 2006-12-13
Publication date: 2008-06-18
Also published as: GB0624824D0

Abstract

A composite door sash 14 has a framework including elongate upper and lower frame members and elongate opposing side frame members 58, 60. The frame members are assembled together with an opening inside the frame members and a skin 62, 64 is fixed to either face of the framework. A sheet of material 66 extends between the frame members across the opening and a foam material 70 is provided in spaces defined between the sheet and each skin inside the frame. The sheet 66 may be made from a fire resistant phenolic material. The foam may be polyurethane foam (PU foam) or phenolic foam. The skin may be formed from glass reinforced plastic (GRP) or PVCU (PVC-U or UPVC). Also claimed is a door frame with an intumescent strip retainer. The retainer 36 is shaped to receive intumescent strip 40 and is mounted to at least one of the frame members. The frame members 18-22 are extruded plastics profiles and a reinforcing member 28 is provided in each frame member to which the respective retainer 36 is affixed by means of screws 43.

Description

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* Doors The present invention relates to doors.

A door typically comprises a door frame which is adapted to be fixed in an opening in a wall or the like, and a door sash mounted to the door frame by means of hinges. The door sash can be pivoted relative to the frame for movement between closed and open positions.

Door frames and sashes have been made in a wide variety of materials.

Traditionally, both the door frame and the door sash have been made from wood. However, modern methods of manufacture have resulted in the increased use of other materials such as metals and plastics for making both door frames and door sashes.

Composite door sashes are known which comprise a framework and a panel or skin fixed to either face of the framework. The space defined between the skins and inside the framework is often filled with an insulating material such as polyurethane (PU) foam, which may be injected into the space or which may be inserted as a panel during construction of the door panel. Composite door sash skins have been made from a number of different plastic or composite materials such as PVC-U, thermoset sheet moulding compound (SMC), or Glass Reinforced Polyester (GRP). The skins may be moulded or otherwise shaped to provide architectural detail for the door. It is also known to use a range of materials to make the framework of a composite door sash, such as wood or wood laminates, plastics and metal. The outer edges of the framework may be exposed or they may be covered so as to match the skins. A known composite door panel having a framework made from aluminium is described in GB236505 I A. In order to comply with various building regulations, it is often necessary for door sashes to be constructed to resist the passage of fire for a given period of time. For example under BS 476: Pt 20: 1987, a door is

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required to resist fire for a period of 30 minutes, though other regulations require a door to resist fire for longer periods of time. To meet these and similar requirements, known composite door sashes are produced using fire resistant materials. For example it is known to fill the space defined between the skins and inside the framework with a fire resistant material such as phenolic foam.

As with the PU foam, phenolic foam may be injected into the space after the skins have been fixed to the framework or inserted as a panel during construction of the sash. To help increase the fire resistance of the sash, it is also known to make the skins from fire resistant GRP.

Whilst the known composite door sash structures are satisfactory, there are shortcomings. For example, injection of phenolic foam requires the use of different equipment from that used to inject PU foam. Hence a manufacturer that produces door sashes having an injected PU core will be required to make additional capital expenditure in order to be able to inject phenolic foam.

Alternatively, it will be necessary to machine a slab of phenolic foam material for insertion into the door. This would again require additional capital investment and will increase manufacturing times and costs.

Accordingly, there is a need for an alternative composite door sash construction which overcomes, or at least mitigates, some or all of the above problems.

Thus, in accordance with a first aspect of the invention, there is provided a composite door sash comprising a framework including elongate upper and lower frame members and elongate opposing side frame members assembled together with an opening inside the frame members and a skin fixed to either face of the framework, in which a sheet of material extends between the frame members across the opening and a foam material is provided in the spaces defmed between the sheet and each skin inside the frame.

A door sash constructed in accordance with the first aspect of the invention has five layers of material in the central region of the sash inside the frarnc members, these being the two skins, the two regions of foam material and the sheet. This compares with only three layers (the two skins and the foam core) in known door sashes. The additional layers of material aid in resisting the progress of fire through the door sash and means that a door sash having satisfactory fire resistance can be produced using conventional PU foam and PVC-U or GRP skins. Alternatively, a door sash having improved fire resistance can be produced if fire resistant foam, such as phenolic foam, and/or skins made from a fire resistant material such as fire resistant GRP are used.

Preferably, the sheet is made from a fire resistant material, it is particularly preferred that the sheet is a phenolic sheet.

The sheet is preferably located substantially centrally of the thickness of the door.

The inner surfaces of the frame members may have slots into which the outer edges of the sheet locate.

The frame members may be made of wood, such as sapele for example, or a wood laminate.

The skins may be made of GRP or they may be made from PVC-U.

The foam may be PU foam or it may be fire resistant foam such as phenolic foam. The foam may be injected into the spaces between the sheet and the skins. Alternatively, the foam may be in the form of foam panels.

The door sash may further comprise one or more glazed panels and/or a letter plate.

In order that a door assembly provides an effective barrier to the passage of fire, smoke and hot gasses, is often necessary to use strips of intumescent material to seal the gap between the sash and the door frame in the event of a fire. Intumescent strips typically comprise an intumescent material housed within a plastics sleeve. In the event of a fire, the strip expands to many times its original volume to seal the gap between the frame and the door sash.

In known door arrangements, intumescent strips are affixed directly into a rebate in the door frame or the door sash using an adhesive. Whilst these arrangements are generally satisfactory, there is a risk that the door frame may distort or move during a fire so that the strip is unable form an adequate seal.

This is a particular problem where the frame is made of extruded plastics frame members.

There is a need, therefore, for an improved arrangement for mounting an intumescent strip to a door frame and for a door frame having an improved means of supporting an intumescent strip.

Thus, in accordance with a second aspect of the invention, there is provided a door frame comprising a plurality of elongate frame members, in which at least one inturnescent strip retainer is mounted to at least one of the frame members, the retainer being shaped to receive at least one intumescent strip.

In a door frame in accordance with the second aspect of the invention, the intumescent strip retainer provides a stable base for the intuniescent strip which is less likely to move during a fire.

The intumescent strip retainer may be made of made of steel or it may be made of a fire resistant material, such as fire resistant GRP or phenolic material.

The, or each, intumescent strip retainer may be shaped to provide one or more rebates or recesses for receiving an intumescent strip. The, or each, intumescent strip retainer may be shaped to provide two or more rebates or recesses, each rebate or recess being adapted to receive an intumescént strip.

The door frame may comprise at least three frame members. The frame may comprise an upper frame member and two side frame members. The frame members may be extruded plastics profiles. The frame members may be extruded PVC-U profiles. Each profile may define a hollow interior and a reinforcement member may be received within the hollow interior of the profile. The, or each, intumescent strip retainer may be secured to a reinforcement member within its respective frame member. The reinforcing member may be made of wood or GRP or the like. The, or each, retainer may be secured to a respective reinforcing member by means of suitable fasteners which extend through a wall of the profile into the reinforcement member. The fasteners may be screws. At least one intumescent strip retainer may be affixed to each member of the frame.

The door frame may comprise at least one intumescent strip mounted to each intwnescent strip retainer.

The frame may further comprise a lower threshold member which extends between the lower ends of the two side frame members. The threshold member may be an aluminium extrusion.

In accordance with a third aspect of the invention, there is provided a door comprising a door sash in accordance with the first aspect of the invention mounted to a door frame in accordance with the second aspect of the invention.

In accordance with a fourth aspect of the invention, there is provided an intumescent strip retainer for use in a door frame in accordance with the second aspect of the invention or a door in accordance with the third aspect of the invention.

The intumescent strip retainer may be shaped to provide one or more rebates or recesses for receiving an intumescent strip. The intumescent strip retainer may be shaped to provide two or more rebates or recesses, each rebate or recess being adapted to receive an intumeseent strip.

There will now follow, by way of example only, a detailed description of one embodiment of the invention with reference to the accompanying drawings, in which: Figure 1 is a front elevation of a door in accordance with the present invention; Figure 2 is a cross sectional view through the door of Figure 1 taken on line X-X; Figure 3 is a cross-sectional view through the door of Figure 1 taken on line Y-Y; Figure 4 is an enlarged view of Figure 2 showing only the upper and lower end regions; Figure 5 is an enlarged view of Figure 3 showing only the left and right hand side regions; and, Figure 6 is a cross sectional view through an intumescent strip retainer forming part of the door pf Figure 1.

A door 10 comprises a door frame 12 and a door sash 14 mounted to the door frame by means of hinges 16 in a conventional manner. The frame comprises three frame members, an upper frame member 18 and two side frame members 20, 22 adapted to be fixed within an opening in a wall, or the like, of a building, or the like. A threshold 24 extends underneath the frame 12 and the sash 14, at least when the sash is in the closed position.

In the preferred embodiment, the frame members 18, 20, 22 are all extruded profiles made of a plastics material such as PVC-U. However, the frame members can be extruded or otherwise formed from other plastics or composite materials if desired. Indeed, in certain aspects of the invention, the frame rnembcrs can be made of any suitable material such as wood or metal and by any suitable method. The threshold 24 is also an extruded profile but is preferably extruded aluminium as this provides a more hardwearing surface suitable for walking on. However, it will be appreciated that the threshold could be made from other materials if desired. For example the threshold could be an extruded plastics profile or it could be made from other metals, such as steel, using any suitable methods.

As can best be seen in Figures 4 and 5, each frame member 18, 20, 22 comprises a hollow profile defining an inner cavity 26. A reinforcing member 28 is received in the inner cavity 26 of each frame member. The reinforcing member may be made of wood, such as sapele, or any other suitable wooden material including laminate. Alternatively, the reinforcing member could be made from a GRP of a similar material and could be filled with penenolic foam.

In a further alternative, the reinforcing member could be omitted altogether and the internal cavity 26 of the profile filled with a phenolic or other fire resistant foam.

Each frame member comprises a main body portion 29 which defmes the inner cavity 26. An inner wall 30 of the main body portion 29 opposes an edge of the door sash when the door sash is closed. At one side edge of each frame member is an extension portion 32 which projects inwardly so as to overly a face of the door sash. A fire resistant seal 34 is mounted to the extension portion 32 for contact with the face of the sash 14 when it is closed. Depending on the desired direction of opening of the door sash 14, the extension portions 32 of the frame members can be arranged to overlie either the inner or the outer face of the door sash.

An intumescent strip retainer 36 is mounted to the inner wall 30 of the main body portion of each frame member 18, 20, 22 in opposing relation to a side edge of the door sash 14, when the sash is closed. The retainer 36 in the preferred embodiments is made from steel, which may be passivated steel, and is shaped so as to provide two rebates or recess 38, 39 opening towards the door sash and which can each receive an intumescent strip 40. As can be seen best in Figure 6, the retainers are formed from a length of sheet steel which is pressed or otherwise formed to define a convex central portion 42 between the two rebates or recesses. The frame members 18, 20, 22 have suitable shaped recesses 41 for locating the retainer 36.

The retainer 36 is fixed to the frame member by means of fasteners 43, which extend through the central portion 42 of the retainer 36 between the two rebates, through the inner wall 30 of the frame member and into the wooden reinforcing member 28. In the present embodiment, the fasteners are screws but any suitable type of fastener can be used. On the side of door which is hinged, the fasteners 43 which secure the hinges 16 to the frame member 22 can also be used to secure the retainer 36 to the frame member. If no reinforcement member is present, the retainer 36 may be secured to the frame member only, by means of suitable fasteners.

The intumescent strips 40 are affixed in their rebates using adhesive in a known manner. Any suitable type of intumescent strip can be used. In the event of a fire, the strips 40 expand to fill the gap between the frame member and the edge of the door to provide a barrier to the progress of fire, smoke and hot gases.

It is preferred that the retainer 36 is made of steel as this is a naterial which can withstand the sort of high temperatures that might be experienced in a fire, for example in the region of 900 deg c, and which can be readily manufactured. However, other suitable materials could also be used. For example, the retainer 36 could be made from a fire resistant material such as GRP or moulded from a phenolic material.

The threshold 24 has three rebates 44 in an upper surface into which are located plastics or rubber inserts 45 to provide a non-slip surface. A further rebate 46 holds a seal 47 for engaging with a lower edge of the door sash 14 when it is closed. The seal 47 is preferably a fire/smoke resistant seal. Further seals 48 are fixed in the lower edge of the door sashl4 for engagement with the threshold. A thermal break 50 is located in an inner chamber of the threshold.

The thermal break may be made of wood or plastics or any other suitable material having a relatively low thermal conductivity compared with aluminium.

The door sash 14 is of composite construction and comprises a frame 52 consisting of four elongate frame members, an upper member 54, a lower member 56 and two side members 58, 60, assembled together to form a planar or lainella rectangular framework having an opening inside the frame members.

In the present embodiment, the door sash frame members 54-60 are made of wood, such as sapele, but they can be made of any suitable material. A skin 62, 64 is fixed to either face of the frame in a conventional manner. The skins may be PVC-U mouldings or they may be made from GRP or any other suitable material. The skins may be moulded or otherwise shaped to provide architectural detail for door. The outer edges of the door sash frame 52 may be covered in strips of the same material as the skins or they may be left exposed.

A sheet of material 66 extends between the inner edges of the frame members across the opening inside the frame members. To hold the sheet in position, slots 68 are formed along the inner edges of door sash frame members 54-60 and the outer edges of the sheet 66 are received in the slots. It will be appreciated, however, that other means of locating the sheet can be used. The sheet 66 is preferably made of a fire resistant material and advantageously may be a phenolic sheet. Phenolic sheets typically comprise a composite consisting mainly of cured phenolic resin and glass fibre. However, the term phenloic sheet is used herein to define a sheet of material comprising phenolic materials, such as phenolic resin and/or phenolic threads.

The sheet 66 is located centrally of the door sash with regard to its thickness so that there is a space between the sheet 66 and each of the skins 62, 64. These spaces are filled with a foam material 70, such as PU foam. The foam typically has a density in the range of 45 to 8Okg/m3 but any suitable foam can be used. Advantageously, the foam is injected into the spaces after the skins 62, 64 have been affixed to the frame. However, the foam material can be provided in panel form and inserted into the spaces before the skins 62, 64 are fixed in position.

The inclusion of sheet 66 means that the door sash 14 has five layers.in the central region inside the door sash frame members, rather than the usual three layer construction, helping to resist the progress of fire through the sash.

As a result, a door sash can be produce which has satisfactory fire resistance properties whilst using conventional PU foam to fill the spaces between the sheet and the skins and conventional PVC-U or GRP skins 62, 64. This is particularly so where the sheet 66 is a phenolic sheet or is made of some other fire resistant material. Alternatively, a fire resistant foam, such as phenolic foam, can be used to fill the spaces between the sheet 66 and the skins and/or the skins can be made of a fire resistant material, such as fire resistant GRP, to provide door sash having increased resistance to the passage of fire.

The usual door hardware, such as lock member 72, may be fitted to the door sash 14 and frame 12. The door sash 14 may be provided with one or more glazed panels and/or a letter plate as is known in the art, with suitable openings being provided in sheet 66 as required.

* The combined assembly of the door frame 12 incorporating the intumescent strip retainers 36 and the door sash 14 with the internal sheet 66 provides an improved door for resisting the passage of fire, smoke and hot gasses. However, it will be appreciated that the door frame 12 including the intumescent strip retainers 36 could be used with a conventional door sash whilst still providing significant advantages. Similarly, the inventive composite door sash 14 with the internal sheet 66 can be used in association with conventional door frame and intumescent strip mounting arrangements.

Whereas the invention has been described in relation to what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed arrangements but rather is intended to cover various modifications and equivalent constructions included within the spirit and scope of the invention.

Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification, they are to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.

Claims

Claims 1. A composite door sash comprising a framework including

elongate upper and lower frame members and elongate opposing side frame members assembled together with an opening inside the frame members and a skin fixed to either face of the framework, in which a sheet of material extends between the frame members across the opening and a foam material is provided in spaces defined between the sheet and each skin inside the frame.
2. A composite door sash as claimed in claim 1, in which the sheet is made from a fire resistant material.
3. A composite door sash as claimed in claim 2, in which the sheet is a phenolic sheet.
4. A composite door sash as claimed in any one of the preceding claims, in which the sheet is located substantially centrally of the thickness of the door.
5. A composite door sash as claimed in any one of the preceding claims, in which the inner surfaces of the frame members have slots into which the outer edges of the sheet locate.

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6. A composite door sash as claimed in any one of the preceding claims, in which the frame members are made of wood or a wood laminate. p....
7. A composite door sash as claimed in any one of the preceding claims, in which the skins comprise GRP.
8. A composite door sash as claimed in any one of claims 1 to 6, in which the skins comprise PVC-U.
9, A composite door sash as claimed in any one of the preceding claims, in which the foam is PU foam.
10. A composite door sash as claimed in any one of claims 1 to 8, in which the foam is fire resistant foam such as phenolic foam.
11. A composite door sash as claimed in any one of the preceding claims, in which the foam is injected into the spaces between the sheet and the skins.
12. A composite door sash as claimed in any one of claims 1 to 10, in which the foam is in the form of foam panels.
13. A composite door sash as claimed in any one of the preceding claims, in which the sash further comprises one or more glazed panels and/or a letter plate.
14. A composite door sash substantially as hereinbefore described, with reference to and as illustrated in Figures 1 to 5 of the accompanying drawings.
15. A door frame comprising a plurality of elongate frame members, in which at least one intumescent strip retainer is mounted to at least one of the frame members, the retainer being shaped to receive at least one intumescent strip.
16. A door frame as claimed in claim 15, in which the at least one intumescent strip retainer is made of steel.
17. A door frame as claimed in claim 15, in which the at least one intumescent strip retainer is made of a fire resistant material, such as fire resistant GRP or phenolic material.
18. A door frame as claimed in any one of claims 15 to 17, in which the at least **** one intumescent strip retainer is shaped to provide one or more rebates or . : recesses for receiving an intumescent strip.
19. A door frame as claimed in any one of claims 15 to 17, in which the at least * one intumescent strip retainer is shaped to provide two or more rebates or recesses, each rebate or recess being adapted to receive an intumescent strip.
20. A door frame as claimed in any one of claims 15 to 19, in which the frame comprises at least three frame members.
21. A door frame as claimed in any one of claims 15 to 20, in which the frame comprises an upper frame member and two side frame members.
22. A door frame as claimed in any one of claims 15 to 21, in which the frame members are extruded plastics profiles.
23. A door frame as claimed in claim 22, in which the frame members are extruded PVC-U profiles.

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24. A door frame as claimed in claim 22 or claim 23, in which each profile defines a hollow interior and a reinforcement member is received within the hollow interior of the profile.
25. A door frame as claimed in claim 23, in which the at least one intumescent strip retainer is secured to a reinforcement member within its respective frame member.
26. A door frame as claimed in claim 24 or claim 25, in which the reinforcing member is made of wood or GRP or the like.
27. A door frame as claimed in any one of claims 24 to 26, in which the at least one claim intumescent strip retainer is secured to a respective reinforcing member by means of suitable fasteners which extend through a wall of the profile into the reinforcement member.
28. A door frame as claimed in any one of claims 15 to 27, in which at least one intumescent strip retainer is aflxed to each member of the frame.
29. A door frame as claimed in any one of claims 15 to 28, in which the door frame Comprises at least one intumescent strip mounted to each intumescent strip retainer.

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30. A door frame as claimed in claim 21, or any one of claims 22 to 29 when dependent on claim 21, in which the frame further comprises a lower threshold member which extends between the lower ends of the two side frame *:. members.
31. A door frame as claimed in claim 30, in which the threshold member is an aluminium extrusion.
32. A door frame substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.
33. A door comprising a door sash in accordance with any one of claims I to 14 mounted to a door frame in accordance with any one of claims 15 to 32.
34. A door substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.
35. An intumescent strip retainer for use in a door frame in accordance with any one of claims 14 to 32 or a door in accordance with claim 33 or claim 34.
36. An intumescent strip retainer as claimed in claim 35, in which the intumescent strip retainer is made of steel.
37. An intumescent strip retainer as claimed in claim 35, in which the intumescent strip retainer is made of a fire resistant material, such as fire resistant GRP or phenolic material.
38. An intumescent strip retainer as claimed in any one of claims 35 to 37, in which the intumescent strip retainer is shaped to provide one or more rebates or recesses for receiving an intumescent strip.
39. An intumescent strip retainer as claimed in claim 38, in which the intumescent strip retainer is shaped to provide two or more rebates or recesses, each rebate or recess being adapted to receive an intumescent strip.
40. An intumescent strip retainer substantially as hereinbefore described, with reference to and as illustrated in Figures 2 to 6 of the accompanying drawings. * *

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