Door and frame

The present invention relates to a door and frame for use as a temporary fire door during the build phase of a building project.

During the build phase of a building project, and particularly the start of the interior fix, there is a common requirement to close door openings at least temporarily to secure a building, or to close an interior room, and for many build projects it is necessary or appropriate to do so using fire doors where possible. This can be even though the interior, and particularly all the interior brick/block or stud walls themselves may not yet be finished - i.e. before the application of plaster finishes.

A common solution for this is the use of low cost timber doorsets, and installing them temporarily in openings in the brick/block or stud walls of the building. As these doors will be exposed to the rigours of the ongoing construction on site, and are thus likely to be damaged before the build project is complete, low cost timber doorsets are best chosen for these temporary installations to avoid financial waste, especially as they get removed and replaced by the final finish doorsets later on in the installation process.

The temporary timber doorsets are also a waste product at the end of the building project as commonly they will have been cut to size to fit into the opening in the wall, or simply get damaged during fitment, use or removal, and thus cannot be reused elsewhere on the building project - or on a later project.

The present invention looks to provide an alternative solution for such temporary doorsets during the build phase of a build project.

According to the present invention there is provided a doorset comprising a frame and a door assembled therein, the frame adapted for front mounting around an opening in a wall.

In some embodiments the door is a certified fire or smoke door, certified, for example, to FD30, FD30S, FD60, FD60S, FD120, FD120S in the United Kingdom, or E30, E30sa, E60, E60Sa, E120 and E120Sa in Europe, tested to the relevant Standard, for example to BSEN1634-1and/or BSEN1634-3, or to equivalent alternative national or regional Standards.

In some embodiments the door and frame have a sprung door closure mechanism for biasing the door towards to a closed position.

In some embodiments the door has a window in it.

In some embodiments the frame and the door feature an intumescent latch and a keep therefor for securing a closed state of the door in the event of a fire. Usually the keep is positioned in an edge of the door and the intumescent latch is provided on a door-edge- facing surface of the frame. In the event of a fire, the intumescent latch - which may have an intumescent layer and a metal sheet overlying the intumescent layer - will expand or displace towards the edge of the door and into the keep. By the intumescent latch being attached to the frame, the intumescent latch will then resist opening of the door due to the engagement of the intumescent latch in the keep.

In some embodiments multiple intumescent latches and keeps may be provided around the edge of the door.

In some embodiments the or each keep is offset slightly versus the intumescent latch before activation of the intumescent latch to allow for warping or bowing of the door prior to said activation and the subsequent expansion/displacement of the intumescent latch into the keep.

In some embodiments the frame and door are both rectangular. In some embodiments the frame comprises two uprights, or legs or jambs, a top member, or a head or lintel, but no sill or threshold. This simplifies the construction of the doorset, and also the installation thereof over the opening: Having one less member around the frame reduces material costs. Further, as this is a temporary door, to use a sill or threshold would position a step across the opening which is undesirable, and thus to provide a sill could require a temporary sinking of the sill into the floor. Further, even if surface mounted to the floor, it would need to be firmly secured to the ground to avoid breakage as the doorway will be a high traffic and high wear location: Workmen in heavy boots will be regularly passing through the doorway, which when mixed with likely rubble or building waste, wheelbarrows and other large (potentially wheeled) equipment, could easily damage or wear the sill or threshold, leading to an early need for replacement.

In place of a sill or threshold, the two uprights of the frame can be connected to the door - by hinges down one side, as is conventional, and by a bolt on the opposing side, which is new. The bolt can be provided along with a spacer between the frame upright and the door edge to provide a fixed spacing around the door between the frame and the door. The doorset can thus be supplied as a fixed frame arrangement around the door, ready for simply screwing to a face of a wall around a doorway opening. In some embodiments, more than one bolt is used around the frame to fix the position, e.g. for transporting the doorset. For example, a second bolt may be provided at the top of the door - mirroring the bottom one for example.

In some embodiments the frame has a width of at least 1 meter and a height of at least 2.2 metres. Such door dimensions are typically larger than conventional single doorway openings in most building projects as doors for people to walk through are typically standardised at widths of between 450 and 950 mm wide. Common widths for single interior or exterior doors are 457mm, 533mm, 610mm, 626mm, 686mm, 711mm, 726mm, 762mm, 813mm, 826mm, 838mm, 864mm, 915mm, 926mm and 991mm, and the most common heights for a door are 1981mm, 1994mm, 2032mm, 2040mm, 2083mm, 2090mm and 2134mm. Although other sizes are also available, they are less commonly used in residential or commercial buildings, or are non-standardised installations.

In some embodiments, the doorset additionally comprises one or more extension member to provide a wider doorset frame, e.g. for accommodating a wider door opening in a wall - for example a double door opening. Multiple extensions may be used for further widening the frame. For example, the, or each, extension member may be a further frame component having a similar or common height to the frame, but having a non-windowed body. It can attach to one of the frame uprights - usually to the side with the bolt, rather than the hinges, although the extension might be adapted instead to attach to the hinge side.

The extension member, by being preassembled onto the doorset, may result in an extra wide doorset - e.g. having a width of at least 1400mm. Alternatively, the extension member may be provided as part of a kit of parts comprising the original doorset and one or more extension member.

In some embodiments the extension member is adapted to bolt onto just one side of the frame.

In some embodiments the extension member is at least 40mm wide and at least 2.2m high.

In some embodiments the door has a door catch or latch, or a door lock, to allow the door to be latched or locked in a closed state within the frame.

In some embodiments the door is attached to a first of the uprights, or the frame, by two or more hinges.

In some embodiments the doors has a security bolt - e.g. a hinge bolt - extending from a hinge side thereof and through the adjacent upright of the frame through a hole in the frame.

In some embodiments the window is a user replaceable window having frame that is screwed or bolted to the door, and removable, the frame extending around a window panel, the window panel being removable and replaceable upon removal of the frame.

In some embodiments the door is made of folded metal sheets, defining an internal cavity that is filled with a fire resistant or fire retardant material, such as rockwool, mineral wall or a phenolic resin foam. In some embodiments the metal is steel.

In some embodiments the extension member is likewise formed from folded metal sheets, defining an internal cavity that is filled with a fire resistant or fire retardant material, such as rock wool, mineral wall or a phenolic resin foam. In some embodiments the metal is steel.

In some embodiments the door is certified as a fire or smoke door, or the doorset is certified as a fire or smoke doorset, to at least a 90 minute, and more preferably a 2hr, Standard, such as British Standard Certification FD90 or FD90S, or more preferably FD120 or FD120S. As before, in some circumstances other Certifications may be adequate, such as FD30, FD30S, FD60 and FD60S in the United Kingdom.

Equivalent European Certifications are also suitable, such as E30, E30sa, E60, E60Sa, E120 and E120Sa.

Ideally for the relevant standard the design of the door or doorset will have been tested and certified to the relevant Standard, for example to BSEN 1634-1 and/or BSEN 1634-3, or to equivalent alternative national or regional Standards.

In some embodiments the frame is formed from one or more folded metal section. In some embodiments it may be an extruded section. Other forms of production may include fabrication, cold drawing, hot extrusion or hot rolling. For example, the frame may be fabricated from two or more L sections welded together. These two L sections may form a side of the frame. Each side may be formed from two L sections. The top may be formed from two L sections.

In some embodiments the metal is steel. For example, the section may be 3mm thick, or more preferably 4mm thick.

In some embodiments the metal section is an L section. This simple form is inexpensive to supply and can be oriented to provide a flat planar surface around the door, formed from the foot or feet of the L section(s), which flat surface is very suitable for quick fixation to a face of a wall.

In some embodiments the metal section is a T-section or a t section or a U section.

In some embodiments for a frame upright, or both frame uprights, and optionally the top or lintel part of the frame is a metal section, the metal section comprising a foot plate with a rear surface for positioning against the wall and an opposite surface for facing away from the wall, first and second flanges extending from the opposite surface of the foot away from the rear surface, and a third flange for providing a door stop for the door. This may be formed from a folded sheet or from two L sections that are joined together, or otherwise fabricated from separate sections. In some embodiments the first and second flanges are parallel to one another.

In some embodiments either or both of the first and second flanges extend perpendicularly away from the opposite surface of the foot plate.

In some embodiments the third flange extends parallel to the foot plate.

In some embodiments the third flange is an extension of the foot plate.

In some embodiments the foot plate, the third flange and one of the first and second flanges are integrally formed and the other of the first and second flanges - usually the one more distal from the third flange - is formed separately but welded to the foot plate.

In some embodiments the third flange is a first sheet of a two sheet thick doorstop, the second sheet of the door stop being integrally formed with the other of the first and second flanges. By being two sheets thick, the door stop can be stiffened.

In some embodiments one of the first and second flanges is longer than the other - usually the one closer to the third flange.

In some embodiments there are webbing plates bridging between the first and second flanges. These stiffen the frame. Preferably such webbing plates are concentrated to be more prevalent or more closely located together wherever they lie close to hinge mounting positions of the door to the frame versus the areas that lie further away from such hinge mounting positions. This concentrates the reinforcement close to the hinges - the forces from the door will concentrate around that area of the frame in the event of a fire due to warping of the door.

In some embodiments the webbing plates are welded to the first and second flanges. They may also be welded to the foot plate.

In some embodiments the webbing plates have a flag-like shape, formed by with a generally triangular flag part (the flag) and a generally rectangular pole part (the pole for the flag), the pole part extending across the opposite side of the foot plate between the first and second flanges and the flag part extending from a side of the pole part and against a surface of one of the first and second flanges - preferably the one closer to the third webbing - preferably the longer of the two.

Preferably there is no capping sheet bridging free ends of the first and second flanges.

In some embodiments there are multiple sections in the frame that are joined together - e.g. by welding or bolts. In the case of a rectangular frame with no sill, there may be three sections, each sequentially positioned around three sides of the door to form a three-sectioned flat planar surface around the door.

With the L sections, the feet thereof provide the flat planar face for positioning against the wall. Like with the other forms, those feet allow the frame to be simply attached to the wall, around an opening therein, for example using screws or bolts.

Screw holes or screw slots can be pre-drilled into the frame, e.g. in the feet of the uprights as they are easier to reach for a builder, although preferably such screw holes or screw slots can likewise be provided in the foot of the top member too, i.e. in all three L sections.

The L sections also provide a leg part, which can be oriented to position parallel to and adjacent the corresponding edges of the door, thus also providing the door surround where the hinges and the latch keep and bottom bolt can be attached to for securing the door therein. In other embodiments, one of the first and second flanges provide this leg part - preferably the one closer to the third flange.

In some embodiments a stop can be formed around the doorward facing surface of the leg parts of the frame to provide a stop for the door. The door will thus then open in one direction, and conventional hinges can be provided - dual directional swinging of the door need not be accommodated. In some embodiments this is a third flange, as previously described.

In some embodiments the stop is a heel for the foot, thus continuing the flat planar face for positioning against the wall. The section of each of the three components of the frame around the door may then be slightly T shaped, albeit (when viewed upside down) typically with a longer foot than heel. An L or T section form for the components of the frame, or the various folds or flanges from a foot portion, provides robustness to the frame. This enables repetitive re-use of the doorset in multiple locations of a build (e.g. moving it to a different area where building work is ongoing when a first area is completed) or in multiple build projects.

Preferably the metal component is formed from folded metal plate (e.g. steel - typically galvanised steel), or an extruded aluminium or plastic section. In some embodiments it may be an extruded section. Other forms of production may include fabrication (usually including welding), cold drawing, hot extrusion or hot rolling. For robustness, metals are preferred. Steel is most preferred as it offers good fire resistance properties.

In some embodiments the material is chosen to have a thickness of at least 4mm.

For the door, again it is preferably formed from folded metal sheeting. However, as it has a larger form, a thinner material can be used. In some embodiments the door comprises a skin enclosing a fire retardant material. In some embodiments the skin of the door is at least 1 mm thick, for robustness, and more preferably about 1 2mm or about 1 5mm thick. Again this provides a robustness to the door that allows multiple re-uses of the doorset.

In some embodiments the extension member is likewise formed with a skin made of a metal sheet that is at least 1mm thick, for robustness, and more preferably about 1.2mm or about 1.5mm thick. Again this provides a robustness to the extension member that allows multiple re-uses of the extension member. Preferably the form of the extension member matches or resembles that of the door, albeit with a top to match the appearance of the top member of the frame and one side that resembles the frame parts overlaid by the other side of the extension member. This then allows the extended-width doorset, with the original doorset and the extension member, to retain a common or more uniform appearance across its front and rear faces.

In some embodiments the door is pre-fitted into the frame for quick installation of the doorset onto a wall - simply by aligning the door in front of an opening in the wall and screwing the doorset (via holes in the frame) to the wall. For some types of wall (e.g. timber framed), the screws can direct drill into the wall. For others, wall plugs, frame fixings or anchors may be needed. However, as exact positioning is not critical due to the temporary nature of its installation, and since it is a surface mount, the installation can be much quicker than trying to fit a frame inside the opening as neither the frame nor the door needs to be cut to size - it is sized to be oversized compared to the opening.

In some embodiments the door is fitted in the frame by hinges on one side of the door and the other side of the door latches with the opposing side of the frame by a latch or lock mechanism towards the middle height of the door. In some embodiments a further bolt connects between the bottom of that opposing side of the frame and the adjacent edge of the door to secure the door within the frame in its closed state during transport and installation of the doorset. This also locks the relative position of the frame relative to that edge of the door, and to ensure a gap between that part of the frame and that edge of the door (to allow the door to swing freely once released), a spacer can be fitted between the frame and the door near or around that bolt. In some embodiments additional bolts are added for securing the door within the frame in its closed state during transport and installation of the doorset For example it is possible to add another in the top edge of the frame above the closing edge for ease of installation.

Upon its installation on a wall, the bolt can be withdrawn or removed to release the door, thus allowing a pre-set configuration of the frame relative to the door during installation of the doorset against the wall to be achieved and retained after the installation. The doorset of the present invention thus needs minimal skill to install - it is pre-assembled in the correct configuration for free-swinging of the door once the bolt is retracted from the door after the doorset’s installation on a wall.

A further aspect of the present invention provides a method of providing a temporary door across a door opening in a wall prior to installation of a final door in the opening during a building project, comprising providing a doorset as defined above, installing it on a front or rear surface of the wall with the door arranged across one side of the opening in the wall, but not in the opening, the door thus providing the temporary door across the opening.

In some embodiments a subsequent door is installed in the opening while the temporary door remains across the one side of the opening, and subsequently the doorset is uninstalled from the surface of the wall. With this further aspect of the invention, there is no need to remove the temporary doorset, which can provide a fire door across the opening, even while the final-fit door is installed in the opening, whereby the installation of the final-fit door, even if it involves multiple tradesmen, or multiple attempts at being fitted correctly, need not be completed upon a first attempt, as the temporary door maintains the security or fire safety requirements for the opening during that installation of the final-fit door. Previously the temporary door would instead need to be removed before the final-fit door can be installed as it would likewise be fitted in the opening, rather than being a surface mount solution.

The present invention also provides a single size of door/doorset, irrespective of the size of the opening to be covered, within reason, rather than needing a specific size to be ordered, or a specific size to be cut to. In particular, the present invention’s doorset is preferably sized to be larger than most typical sizes of opening for single door installations. A single size of doorset of the present invention can thus be used across multiple different door opening sizes during a building project - even sizes of opening that are smaller than the pre-installed door of the doorset!

Furthermore, given the resilience of the materials used for the doorset - typically metals rather than timber, the doorset of the present invention can be used on multiple projects for multiple door installations, rather than being a single use waste product at the end of a build project.

These and other features of the present invention will now be described in further detail with reference to the accompanying drawings in which:

Figure 1 shows an isometric view of a first embodiment of doorset in accordance with the present invention;

Figure 2 shows a front elevation of the doorset of figure 1 ;

Figure 3 shows a rear elevation of the doorset of figure 1 ;

Figure 4 shows a top plan view of the doorset of figure 1 ; Figure 5 shows a side elevation of the doorset of figure 1 ;

Figures 6 and 7 show details D and E from figures 2 and 5;

Figure 8 shows a second embodiment of doorset in accordance with the present invention, in which an extension member is added to the doorset of Figure 1 to produce an expanded-width doorset;

Figure 9 shows a rear elevation of the doorset of figure 8;

Figure 10 shows a front elevation of the doorset of figure 8;

Figure 11 shows a top plan view of the doorset of figure 8;

Figure 12 shows a perspective view of the extension member from figure 8;

Figure 13 shows a rear elevation of the extension member of figure 12;

Figure 14 shows a side elevation of figure 12;

Figure 15 shows a top plan view of the extension of figure 12;

Figure 16 shows a detail I from figure 15;

Figure 17 shows a rear perspective view of a modified door for use in the invention with keeps or trays positioned in the edges for use as strikes for intumescent locks that can be added to the frame to face towards the keeps or trays;

Figure 18 shows a rear perspective view of a modified frame featuring the intumescent locks, and also further stiffened by a return flange and webbing plates;

Figure 19 shows a rear perspective view of the door of Figure 17 fitted in the frame of Figure 18 to form a further doorset of the present invention;

Figures 20 to 26 show the construction and function of the intumescent latch; Figure 27 shows a front view of the doorset of Figure 19;

Figure 28 shows a right side view of the doorset of Figure 19;

Figure 29 shows a rear view of the doorset of Figure 19;

Figure 30 shows a left side view of the doorset of Figure 19;

Figure 31 shows a top down view of the doorset of Figure 19;

Figure 32 shows a bottom up view of the doorset of Figure 19;

Figure 33 shows in more detail a hinge side of the door and frame from below, detailing the highlighted area of Figure 32;

Figure 34 shows a non-linear cut-through of the doorset of Figure 19, showing the window and the door lock; and

Figure 35 shows a modification for the mounting of the frame to a wall, using a frame shroud or fixing extension.

Referring to figure 1, there is shown a doorset in accordance with the present invention. The doorset comprises a frame 1 and a door 2.

The frame comprises a metal three-part construction, with two uprights and a top member. The metal can be steel - for example galvanised or painted steel. Other metals, or even plastics, can also be used.

Each component of the three-part construction has a generally L-shaped section, with a foot for lying against a wall upon installation, and a leg for facing an edge of the door. The feet of the three components define a flat planar surface for facing the wall. The foot can have a heel to define a stop for the door, which heel extends from the opposite side of the leg to the foot, albeit still at the same end of the leg. The heels are shown provided on all three components, and thus form the stop around three sides the door. As there is no sill, there is no stop at the bottom of the door, although to have a stop there would be a nuisance to builders, who may regularly wheel materials in a wheelbarrow through the doorway.

Because of the stop, in this embodiment the door will open in one direction - towards the viewer in Figure 2, and away from the viewer in Figure 3.

In this embodiment the stop is a heel for the foot, thus continuing the flat planar face for positioning against the wall. In other embodiments it might be stepped back from that flat planar face.

The section of each of the three components of the frame around the door, although generally L shaped, forms a slightly T shaped form (an inverted T shape with a longer foot than heel) in this illustrated embodiment.

The heel provides a longer flat planar against the wall than can be seen from the front of the frame. This can be seen in Figures 2 and 3 by comparing the thickness of the frame as viewed in Figure 3 compared to that which remains visible in Figure 2. In Figure 2, only the foot can be seen, but in Figure 3 the foot and the heel can be seen - the door masks the heel (the stop) in Figure 2.

In this embodiment the door 2 has a window 6. The window 6 is seen as a single pane of glass, which may be double glazed or steel reinforced in some embodiments. Other window arrangements are also known in the art, and may instead be provided - for example multiple windows or multiple panes. A window is preferred to be present as it allows builders to see through the door to improve safety awareness. However, the window is not essential.

The door in this embodiment is attached to the frame by multiple hinges - in this case three, to the right hand edge of the door as seen in Figure 2. The hinges attach to the edge of the door and to the right upright 24 of the frame 10. In this embodiment the hinge fits to the outside face of the frame and the outside face of the door, rather than being recessed therein. This simplifies the design, as profiling the sections and door becomes non-essential, which helps reduce costs, provides a default spacing between the door and the right upright (the thickness of the hinge plate) and avoids the provision of areas of weakness in the frame, such as can occur when thinning the material of the frame, or the wall of the door, for receiving the hinge plate.

Conventional hinges can be provided - dual directional swinging of the door need not be accommodated due to the presence of the stops. Further, it is preferred that rising hinges are not provided as they can make it harder to provide fire sealing around the door between the door and the frame, if required.

The frame 10 also has a left upright 26 and a top member 28. In the art the uprights are also sometimes known as legs or jambs and the top member is also sometimes known as a head or lintel.

As this doorset is typically for use as a fire door, an automatic door closing mechanism is also provided. In this embodiment there are two door closing mechanisms. The first is a surface mounted sprung door closure mechanism 18 fitted between the top member 28 and the top of the door 12. Such automatic door closure mechanisms are well known in the art. The second is a hinge-side internally mounted closure spring. Such closure springs are also well known in the art. Providing both is preferred as the door will usually be a heavy door, being larger than conventional doors, and being typically made of steel, and being typically filled with a fire retardant material so that the doorset can be certified as a fire doorset.

In some embodiments, however, one or other of the door closure mechanisms, or both, can instead be omitted, or replaced with other known forms of automatic door closure.

A latch operated by a handle 30 is also provided - in this embodiment to the left edge of the door. It allows the door to be latched in a closes state. Conventional latch mechanisms can be used, as well known in the art. In this embodiment a key operated lock 34 is also provided. This is to allow the door to be locked shut for security purposes, although this is optional.

For the latch and the lock, a keep is provided in the left upright 26 - see the alternative embodiment with an extension member where the recesses for the keep 32 can be seen (figure 14); corresponding holes can be provided in the frame upright as the keep 32. The lock may be a deadbolt lock.

In this embodiment, the handle 30 is of a lever type. However, a door knob type, or other locking or latching handles, can be used instead.

A grab handle 34 is also shown on the front of the door 12 in figure 2. This grab handle may be more convenient for some users to use when pulling the door open. It is optional.

The three components 24, 26, 28 of the frame 10 can be joined together in a known manner. They may be formed as a single piece, which is cut and folded into shape. However, in this embodiment three separate components are formed with mitred corners and the mitres are welded together to form the rectangular shape as shown. The door 12 can then be fitted into the rectangle of the frame 10 using the hinges and the bolt/latch/lock.

In some embodiments, additional door security can be provided by providing a security bolt on the hinge side to prevent removal of the hinge from releasing the hinge side of the door, as also known in the art.

In this embodiment, the door 12 is hingedly mounted to the frame 10 with three hinges 32. These may be equally spaced along the edge of the door 12. However, as shown, in this embodiment they are positioned so that a single hinge is provided towards the bottom of the door and a pair of hinges are provided towards the top of the door. The top hinges will be in tension when the door is hanging on the hinges so having a pair of hinges at the top is preferable to carry that loading. The hinge at the bottom is instead in compression and is thus less likely to fail, so a single hinge at the bottom is generally enough.

The components 24, 26, 28 of the frame 10 are preferably formed of a folded steel section. Such a simple construction for the frame 10 keeps costs to the minimum.

Preferably the metal sections are formed of at least 4mm steel thickness, more preferably 5mm steel thickness. This is heavier than usual frame sections, which more typically are made of 2mm steel or less. However, as this doorset is likely to be heavily abused during the building project due to the moving therethrough of lots of building materials, the increased gauge of the metal is preferred to provide suitable rigidity and toughness thereto to survive the full build project, and to be still useable at the end of the project for reuse on other projects.

Predrilling of screw holes or screw slots in the frame - in the feet of the frame - allows the frame 10 to be easily screwed to the surface of a wall for installing it over an opening in the wall. In this embodiment, the screw holes and screw slots are formed in the feet of the L sections which feet 40 lie parallel to the surface of the wall. Perpendicular thereto is the leg 42, which legs of the three components 24, 26, 28 provide door facing elements of the frame 10. This is best shown in figure 4. See also figure 1 for the perspective view thereof.

The screw holes 36 are shown spaced along the two uprights 24, 26 - with four thereof in each upright 24, 26. Screw slots 38 are then shown interposed between the screw holes 36. There are thus three screw slots 38 in this embodiment, on each upright 24, 26. Different numbers and different combinations of screw slots and screw holes can instead be provided. For example, there may just be screw holes or there may just be screw slots or there may be different combinations of screw holes and screw slots.

In this embodiment, the top member 28 is shown to have two screw slots 38 and two screw holes 36. They also are positioned spaced apart along the top member 28. Again, however, they can be differently arranged in different combinations, numbers or arrangements.

The use of screw slots 38 is preferable to just screw holes as screw slots allow greater flexibility in mounting positions for the frame 10 relative to an opening in a wall. For example, if attaching to a stud wall, it is desirable to screw the frame 10 to the studs or bracers in the stud wall, rather than just to the plasterboard, as the screws will otherwise be more inconvenient to fit (plasterboard fixings would be needed). With screw holes there is a greater chance that the fixed positions will not align with such studs or bracers, compared to screw slots due to the elongation of the slots giving greater location flexibility. However, having multiple screw holes or screw slots is also preferred as that can give the greatest likelihood of a suitable alignment of the frame holes 10 with such studwork. Likewise for brickwork walls or blockwork walls, it is desirable if possible to mount the frame to the mortar lines between the bricks or blocks, rather than into the bricks or blocks themselves, as to screw into the blocks will involve the use of a hammer drill, which can displace the brickwork, or weaken the bond of the mortar thereon. Having multiple screw holes and multiple screw slots thus again gives the best likelihood of a suitable and simple attachment of the frame to the wall. However, in most wall types, a firm fixation should still be possible whether just screwing into studs or mortar joints or whether attaching elsewhere as well; through multiple fixations - using a significant number of the multiple screw slots and screw holes provided, such a secure fixation should be readily achievable.

As discussed above, the frame 10 will be surface mounted to the wall across an opening therein. This may be an interior or an exterior wall. The frame can be fitted to either side of the wall, although for an exterior wall it would more preferably be applied to the internal side of that so that access to the screws that mount the frame to the wall is prohibited from outside the building - the screws instead will be internal of the building.

By surface mounting the frame to the wall, rather tian fitting it in a doorway opening in a wall, the frame and door of the present invention do not prevent access to the opening in the wall, whereby a final door and door frame can be fitted into the opening in the wall even while the doorset of the present invention is located on the wall. This is a particular advantage of the present invention compared to the prior art approach of fitting a temporary timber door and frame into the opening - which by being fitted in the opening has to be removed before the final door and frame can be installed.

Referring again to figure 2 there is shown at the bottom of the door 12 a kick plate 20. Such kick plates 20 are known in the art and can be simply screwed, riveted or spot welded to the front of the door 12. Although optional, providing a kick plate provides additional resilience to misuse of the door, and is thus desirable.

In this first embodiment, the door 12 is formed of folded sheets of steel to provide an outer casing for the door, with the inside of the door being infilled with fire resistant materials, such as mineral wool, rockwool, or phenolic foam. In preferred embodiments the doorsets will be designed to pass the relevant standards for fire doors and doorsets, such as British Building Standards such as FD120 or FD120S. Such doors are rated to resist fire for two hours (120 minutes). A skilled person is familiar with these types of fire door Standard, including British Standard 476 part 22:1987 or British Standard EN1634- 1 2014,. BSEN1634-1 and/or BSEN1634-3, and will know how to specify material choices and thicknesses for the skin (e.g. the metal sheets) and the infill (e.g. the mineral wool, rockwool or phenolic resins) so as to meet such standards, including how to have the doors and doorsets so certified, whereby a further discussion is not needed herein. It is to be observed though that the above-mentioned materials and sheet thicknesses can readily exceed the minimum requirements required for meeting such standards.

Where the door is certified as a fire or smoke door, or the doorset is certified as a fire or smoke doorset, this might instead be fora shorter duration, such as 30, 60 or 90 minutes, although a 2 hr (120 minute) certification is preferred. Such British Standard Certifications include FD30, FD30S, FD60, FD60S, FD90 and FD90S. Equivalent European Certifications are also suitable, such as E30, E30sa, E60, E60Sa, E120 and E120Sa.

Ideally for the relevant Standard Certification the design of the door or doorset will have been tested and certified to the relevant Standard, using the relevant testing processes, or to equivalent alternative national or regional Standards.

Turning to figure 3, a window 16 is shown to be fitted to the door 12, and in this example it is provided as a cassette window, with a removable frame 24 extending around this window pane. In this example, the removable frame is provided as four mitred elements that are screwed or bolted to the rear surface of the door 12 to hold in place the window cassette 46. Using screws or bolts is preferred as they can then be easily removed to replace the window cassette 46 in the event that the window cassette 46 was to be broken during use of the doorset in the building phase of the building project. This ease of replacement is another benefit of the present invention’s design. However, in other embodiments the frame may be riveted or welded to the door, making the window more secure and harder to remove, which may be preferred for a security door.

Using a window cassette allows afire approved design to be bought off the shelf, which assists with meeting fire standard certification. Making the frame easy to remove and thus the window cassette easy to replace is a significant advantage of the present invention compared to user-replaceable window panes, which may not pass the fire and smoke testing Standards.

As shown in figure 3, the rear side of the door 12 has a handle 30 and a lock 34, like the front of the door, and they communicate with the respective opposing door handle 30 and lock 34 on that other side of the door. However, in place of the grab handle 35, on the other side of the door, as shown in figure 2, this rear side of the door 12 is provided with a push plate 48. Although optional, this push plate 48 is preferred to be provided as the door is arranged to open inwardly, i.e. away from a person at the rear side of the door - into the page in Figure 3. As such, a grab handle 35 is counterintuitive. Nevertheless, it is possible for a grab handle 35 to instead (or additionally) be provided.

It should also be appreciated that neither side has to have a grab handle, nor a push plate 48.

On the rear side of the door, at the bottom thereof, another kick plate 20 is provided. This kick plate 20 is again screwed, riveted or spot welded to the door, but in this embodiment it is positioned over an automated bottom seal mechanism. This mechanism can be one to automatically raise and lower a bottom door seal upon opening and closing the door, using a hinge-side trigger mechanism. Such automated seal mechanisms, often referred to as drop seals, are produced by companies such as Lorient, and are preferred to be provided on doors of the present invention so that when the door is closed in the frame, the door seal drops against the floor, but when the door starts to be opened the hinge-side trigger mechanism releases to lift the spring seal member located at the bottom of the door. It will nevertheless be recognised, however, that the use of a drop seal is optional, as is the use of a kick plate. It is also possible instead for the kick plate 20 simply to overlay the bottom of the door.

Although optional, this door sealing mechanism is preferred to be provided as it provides a raised bottom for the door when the door is open, as often the door will need to clear dust or rubble on the floor, yet a closer seal against the floor when the door is not in use (i.e. closed), thus offering better smoke and fire protection for the building.

In addition to the bottom seal, a smoke seal or intumescent strip may be provided around the edge of the door - between the frame and the door - or a smoke seal or intumescent strip may be located in the frame to face towards the door. Such seals are well known in the art and can further improve fire and smoke safety from the doorset.

One thing absent from this doorset is a sill or threshold. This is intentional as providing a sill or threshold would provide a high wear item of the doorset, and potentially a step due to the quick intended installation method (simply front mounting to the wall), both of which is undesirable as such a sill or threshold would likely be broken or significantly damaged during each fixed installation of the doorset, making the doorset less likely to be repeatedly reusable on different projects, locations or jobs. In particular, it may need replacement, or it could render ineffective the certification of fire resistance between installations of the doorset, thus requiring replacement of the whole doorset. Instead the doorset of the present invention is provided without a sill or threshold.

One function that a threshold or sill usually provides for a pre-assembled doorsets is a retaining function for the base of the frame - as otherwise the base of the frame is open and thus can be damaged in transit. In the present invention, however, that problem is resolved by the provision of a bolt and spacer at the bottom of the left upright - i.e. the upright without the hinges. With that bolt and spacer, in combination with the hinges on the other upright, the left upright is fixed to the door such that the spacing between the door 12 and the frame 10 is fixed across all three sides of the door against which a frame component is present - i.e. the two uprights and the top member. The hinges secure the first upright and the bolt and spacer secures the second upright, with the latch or lock offering further support too for the second (here left) upright. The frame 10 is thus secured relative to the door, with correct spacing all around the frame, both during delivery and installation of the doorset onto the surface of the wall around an opening. Only after the installation does the bolt and spacer get removed (or retracted).

It is preferred that the bolt also has a retainer so that it cannot easily be removed from the frame, such that it stays in the frame even after releasing the door. In some embodiments the retainer can also be provided to retain the spacer, or the spacer can be attached elsewhere to the frame. The bolt, and preferably the retainer too, thus will not be lost, allowing it or them to be reused to lock the frame upright to the door again when the doorset is wanted to be removed for reuse elsewhere. For receiving the bolt, the edge of the door 12 is provided with a threaded hole that aligns with the bolt when the door is closed.

The spacer is preferred as it helps to prevent that bolt 14 from overly tightly connecting its upright to the edge of the door 12, whereupon after installation the frame would interfere with the door, making the door hard to open and close. The spacer 50 is thus pre-fitted between the frame upright 26 and the door 12 so as to pre-define a consistent gap at the bottom, and the rest of the frame is sized around the door to maintain that spacing along the length of the upright 26 (the opposing edge of the door has similar spacing due to the multiple hinges, and with the hinges and the bolt cooperating to secure the door in the frame, the top member can likewise have its spacing maintained - preferably a similar gap again.

After installing the doorset to the wall, the bolt 14 can be undone and the door spacer 50 can be removed, retracted or relocated, thus leaving the installation with the correct spacing around the door in the frame so that the door can open and close as appropriate.

In a simple embodiment, the bolt can be fully removable from the leg, but will be left in the leg 42 by the installer, albeit in a contracted condition (away from the edge of the door, and out of the threaded hole), albeit with the spacer fitted on to that bolt on the other side of the frame (away from the door edge), as that will keep the bolt and spacer safe, whereby when the doorset is to be removed from the wall for re-use elsewhere, the bolt and spacer can simply be reverted to the transport configuration - attached into the threaded hole in the edge of the door 12 with the spacer between the upright and the door for re-setting that fixed spacing during transport of the doorset to its new location.

Although described above as being fitted to the left upright 26, the hinges may instead be mounted on that left upright and the bolt and door spacer 40, 50 could instead then be mounted on the right upright, and the threaded hole for the bolt can then be in the right edge of the door 12.

This bolt and spacer arrangement is shown in more detail in figure 7.

Referring next to figure 6, the mounting of one of the hinges is shown in more detail. As can be seen, rivets, nuts, bolts or screws may be used for this purpose. In this preferred embodiment, as shown in figure 5, the two hinge plates of the hinge 22 are provided such that one hinge plate is provided on the right upright 24 - on the outside surface of that leg, whereas the other hinge plate of the hinge 22 is provided to the outer surface of the adjacent edge of the door. With this arrangement there is no need to recess the hinge plates into the edge of the door or into the upright of the frame section - they can simply be surface mounted. It is of course possible to instead recess them into the surfaces thereof, if preferred, as that could give a cleaner finish. However, simplicity of constructions is preferred for this temporary use doorset, to keep costs to a minimum, and there is less emphasis on aesthetics for the product as it is not for a final fit purpose. Such surface fitting will still provide the desired clearance between the frame and the door (at least the thickness of the hinge plate, and it is common for hinges to not close both hinge plates into parallel contact to one another, so there is a natural spacing anyway between the hinge plates (when lying parallel to and overlaying one another). By choosing a hinge with a natural spacing to match or exceed the thickness of the material for the upright, or providing the upright with a thickness to match or be less than that natural spacing of the hinges, the door can still close without stressing the hinges and while providing a required clearance between the door and the upright when the door is closed.

Referring next to figures 8 to 11, the doorset of figures 1 to 7 is shown in combination with an extension member 52. The extension member 52 is attached to the original doorset’s frame 10 for widening the doorset into an extended doorset. The extension member 52 is shown on its own in figures 12 to figure 16. This second embodiment may be suppled as a kit of parts comprising the doorset of figures 1 to 7 and separately one or more extension members as per figures 12 to 16, or in fully assembled form where the extension members will be attached to the frame 10 of the doorset of figures 1 to 7.

The extension member 52 is attached over the left upright 26 of the original doorset - bolted thereto using the screw holes 36 and screw slots 38 in that left upright 26. In other embodiments it may be arranged for bolting to the other upright.

Figure 9 shows the bolt screws 54 extending through those screw holes 36 and screw slots 38. The bolt screws 54 extend into receiving threaded holes 56 in the extension member 52, which holes 56 are shown in figure 12. See also figure 11. Upon bolting that extension member 52 to the previous doorset, a wider width of opening can be accommodated by the extended doorset. To allow the extended doorset 58 to be attached to the wall, the extension member 52 also has various screw holes 36 and screw slots 38 in a flanged edge 40 thereof - the flanged edge resembles the foot 40 of the L section of the original frame 10. The screw holes 36 and screw slots 38 in this embodiment are thus similarly alternating up and down the flanged edge of that extension member 52.

There are also one or more screw holes or slots in a top flange 40 of the extension member 52 - as shown there is a single screw hole 36 in this embodiment, although a different number of holes or slots or just a slot can instead be provided.

This extension member 52 typically will be formed with a similar material structure as that of the door, namely a metal sheet body filled with a fire retardant or fire resistant material, such as mineral wool, rockwool or phenolic resin foam.

The thickness and colour (e.g. if painted) of the extension member may also match that of the door, for providing a common or matching appearance.

In this embodiment no window is provided in the extension member, although one can be provided if preferred.

In this embodiment the extension member is about 400mm wide, and has a height to match that of the first doorset. Other widths are also possible - e.g. much wider extension members. A double or triple width extension member, or an extension member having a width of about 900mm, 1m, or to match that of the original frame set, is also possible to allow a simple extension to bridge across a double width door opening in a wall.

As shown in figure 12, the edge of the extension member 52 that faces the door 12 can be provided with latch and lock keeps 32, much like the left upright 26. They can be holes in the edge thereof. They would line up with the keeps 32 in that left upright 26 so that the latch and lock of the door can still operate.

In a preferred embodiment, the profile of extension member where it overlies parts of the frame 10 of the original doorset can be recessed for accommodating the parts of the frame - so that the combined extended doorset (the original frame 10 and the extension member 52) can still present a flush planar surface for lying flush against the wall. In the illustrated embodiment, however, no such recess is provided so there will be a small step - the thickness of the material of the frame high, in that planar surface in the extended doorset. However, as the doorset will typically be applied to an unfinished wall, such small irregularities in that wall facing surface (i.e typically less than 5mm) will not present a problem, and as builders regularly use spacers or packers (usually made of various colours of plastic) for fitting windows or doors, they will be able to pack any spaces with them, if needed.

In some situations, more than one extension member may be needed to further extend the doorset, e.g. if need for a particularly wide doorway. For example, for a double doorway, two or more extension members may be required, especially if an extra wide extension member (such as those discussed above) is not provided. As a double wide door is not typically going to be required during the building process, it will be acceptable temporarily to close a double doorway with the extended doorset, even though it will only have the single door (of the original doorset). That single door can be used for the temporary purpose of the present invention - i.e. during the building process, even over such double wide doorways.

Referring next to Figure 17 an alternative door 12 is shown. This door 12 may be fitted to the frame 10 of the previous embodiment or to the frame 10 of the embodiment of Figure 18. The door 12 is similar to the previous door 12, and thus has largely the same features. However, various details are changed or modified, and some additional or alternative features are added. These changes or features are typically optional as the feature set for the door (and doorset) can vary widely depending upon customer requirements.

As shown, the size and orientation of the window 16 is changed. Further, a signage holder 60 has been provided on each side of the door 12.

In this embodiment, the door handles 30 for turning a latch of a lock 34 are not provided, although the grab handle 35 is shown. Instead of the turnable latch, a deadlock 34 with a deadbolt 82 are provided, turnable instead with a key, or some other mechanism. In this illustration the keyhole is covered with an escutcheon or blanking plate cover, although in practice the face of the door to which locking or unlocking access is desired to be granted can be uncovered so that a key can fit in the lock to provide that function. A finger turn handle may also be provided if desired - usually only to one side.

Keeps or trays 68 are provided in the top edge 62 and the free side edge 68 of the door 12 into which intumescent latches 72 can extend from the frame 10 in the event of a fire. This is discussed in further detail below with reference to Figures 20 to 26. The number and position of these keeps is highly variable, dependent upon client requirements, although the illustrated provision of more down the free edge 62 than at the top is preferred.

It is typically not necessary to provide these down the hinged side 66 of the door 12 as the hinges 22 and dog bolts (holes 92 for which - in the frame 10 - are visible in Figure 19) securely hold that side of the door 12 in the frame 10. Likewise they are not needed in the bottom as there is no bottom frame member in this embodiment.

A finger plate 17 is provided, as provided in the previous embodiment.

The kick plate 20 is again provided, and as in the previous embodiment this is shown to be provided with an automated seal mechanisms, often referred to as a drop seal, which again is preferred but optional.

A bolt 14 and spacer 50 are also again provided at the bottom edge of the door 12 for the purpose previously discussed for the previous embodiment, and again is optional but preferred.

A door closure mechanism 18 is also provided at the top 62 of the door, as per the previous embodiment.

Referring next to Figure 18, a modified frame 10 is shown for receiving the door 12 of either embodiment, but preferably the door 12 of Figure 17 due to the provision of intumescent latches 72 along respective parts thereof for facing the keeps / trays 68 of that door 12. As will be discussed below, with reference to Figure 20, the intumescent latches 72 are fitted to the frame by two connection bolts 86 and there is also a cover plate 84 for each intumescent latch 72 for closing a hole 104 in the frame 10 into which a spring 98 of the intumescent latch 72 fits. In this embodiment there is one intumescent in the top part of the frame - substantially opposite a keep that is near the free edge end of the door 12, and five along the side part of the frame 10 that is located opposite the free edge side 64 of the door 12. These five are distributed above and below the deadbolt 82, with three above and two below the deadbolt 82. More are positioned above as that corner of the door, if it warps in the heat of a fire, allows faster distribution of heat from one room to the next than a corresponding warping of the bottom edge, due to the fact that hot air rises. Also, this arrangement is because the space below is usually shorter than the space above, so the warping can theoretically be further, as the deadbolt 82 is usually positioned below the midpoint of the door edge 64. More may be added where necessary to suitably restrain the door when exposed to fire conditions or for doorsets of a much larger nature in height and width.

The top part of the frame also has a bracket 74 provided on it for receiving a part of the door closure mechanism 18.

In this modified frame 10, the structure thereof is reinforced versus the L or T shape of the previous embodiment. For this purpose the section has an additional flange and webbing plates.

As before the frame 10 has a basic L shape in section, but this just forms a core shape of the section, with the foot 116 of the L forming a foot plate 116 with a rear surface 124 for positioning against the wall and an opposite surface 126 for facing away from the wall, and the leg 118 forming a first flange 118 extending from the opposite surface 126 of the foot 116 away from the rear surface 124. There is then, however, a second flange 120, spaced from the first 118, also extending from the opposite surface 126 of the foot 116 away from the rear surface 124. Finally there is a third flange 122 for providing a door stop (or frame stop) 114 for the door 12, much like in the previous embodiment. However, in this embodiment the section is now formed from two separate parts 128, 130 that are welded together at a weld line 132, as shown in Figure 33. As shown in Figure 33, the first part 128 is a first L section 128 that provides the leg or first flange 118 and the door stop 114 against which the door 12 can close, although a sealing member 110 is also provided for the door to seal with, preventing contact between the door 12 and the first L section 128. The second part 130 is then a second L section 130 that provides the foot 116, the second flange 120 and an extension of the foot that backs onto the door stop 114 to double its thickness. The weld line 132 then joins these two L sections together along their length (or intermittently along their lengths) at the ankle of the core shape of the section.

In this embodiment the frame stop 114 and the third flange 122 are coterminous at their free ends, and may be welded together at those ends. Alternatively it might be possible to form this section in a single folded sheet where there is a bend between these free ends.

The hinges 22 are attached - for example by screws, bolts, rivets or welds - such that one of the leaves thereof is between the leg (first flange) 118 and the door 12 and the other of the leaves thereof is to the other side of the leg (first flange) 118. Thus the hinge’s gait (thigh gap) defines the thickness of the leg 118 (or the hinge is chosen with an appropriate swage to so fit.

In this embodiment the foot 116 and the third flange 122 are parallel and in line with one another and are formed from a continuous leg of the second L section 130.

In this embodiment the first and second flanges 118, 120 are parallel and spaced from one another with the foot extending between their ends. The third flange is thus an extension of the foot plate.

In this embodiment both the first flange 118 and the second flange 120 extend perpendicular to the opposite surface 126 of the foot plate 116.

In some embodiments the third flange extends parallel to the foot plate.

In some embodiments the foot plate, the third flange and one of the first and second flanges are integrally formed and the other of the first and second flanges - usually the one more distal from the third flange - is formed separately but welded to the foot plate. Here, it is the second flange 120 that is integrally formed with the foot plate 116 and the third flange 122, and the first flange is integrally formed with a second layer of the third flange, which second layer is the door stop 114, as this provides a stiffer door stop 114 - due to its backing by the third flange. The third flange 122 is thus part of the door stop 114 too.

In this embodiment the first flange is longer than the second flange - the first flange (leg 118) it is the flange that is closer to the third flange (the frame stop) 122/114. It is provided to extend such that it’s free end lies substantially flush with the rear of the door 12.

In this embodiment, to provide a stiffened edge for the door, the door features an L sectioned element 112. That provides a hanging-edge stiffening function as it is internal of the folded edge of the door 12.

The door 12 or the frame 10 also has a dog bolt 92 for increasing the security of the door within the frame. In this embodiment it extends from the frame 10 and into the edge of the door 12 - through a hole in both the folded edge and the L sectioned element 112 in this embodiment.

In this embodiment there are webbing plates 76 bridging between the first and second flanges 118, 120. As shown in Figure 29, the webbing plates are concentrated more closely together in the area of the frame 10 to which the hinges 22 are mounted to the frame, versus the areas that lie further away from such hinge mounting positions. This is to impart additional stiffness in those areas as the hinges will focus the forces in those areas from a bowing of the door in a fire.

In this embodiment the webbing plates 76 are welded to the first and second flanges 118, 120 and extend perpendicularly between those flanges 118, 120. They are also welded to the opposite surface 126 of the foot plate 116.

In this embodiment the webbing plates 76 have a flag-like shape, formed by with a generally triangular flag part (the flag) and a generally rectangular pole part (the pole for the flag). This is illustrated clearly in Figure 33 in which an imaginary line of separation is shown by the dotted line therein. The pole part extends across the opposite surface 126 of the foot plate 116, between the first and second flanges 118, 120. The flag part extends from a side of the pole part and against a surface of the first flange 118 that faces the second flange 120.

There is also shown a bottom plate at the bottom of each frame side piece with a hole 88 in it for use as a fixing point for the frame 10 to the floor. See it also in 19.

In this embodiment there is no capping sheet bridging free ends of the first and second flanges 118, 120. This ensures there is easy access to the screw holes 36 and screw slots 38 in the foot place 116 for mounting the frame 10 to the wall. However, boxing it with such a capping sheet may offer additional rigidity to the frame, and thus may be provided in some embodiments.

Referring next to Figures 20 to 26, the intumescent latches 72 and their inter engagement with the keeps 68 in the edges of the door 12 will be further discussed.

With reference to Figure 20, the intumescent latches 72 are fitted to the first flange or leg 118 of the frame 10 by two connection bolts 86. These connection bolts 86 are formed from a screw 96 and a spacer 94, with the screw 96 having a head larger than a hole through the spacer 94 and a shaft smaller than the hole so that the shaft fits inside the spacer 94.

They are attached to the frame with a bolt 97 that is sized also to extend inside the spacer 94 to engage with the screw 96. The spacer 94 thus surrounds both the screw 96 and the bolt 97.

A hole 106 through the first flange 118 for receiving the bolt 97 is sized to be smaller than the spacer 94 so the spacer sits on one side and the head of the bolt 97 sits on the other side of the first flange 118.

In this embodiment the spacer 94 is a tube of thermoplastic, such as polyethylene, such that it softens in the vicinity of a fire - e.g. at a temperature of perhaps more than 70°C.

Between the holes 106 in the first flange is a further hole 104 - in this embodiment bigger than the bolt holes 106, the further hole 104 being provided for a spring of the intumescent latch 72. The spring hole 104 is made blind with a cover plate 84 on the same side of the first flange 118 as the spacers 94. The spring can then be sandwiched in the hole 104 by the intumescent latch 72 by positioning thereover an intumescent 100 and a lock plate 102, which bridge across the two bolts 97 and the spring 98.

At the time of installation, the intumescent 100 is unexpanded and may be approximately 1.3mm thick as it is preferably a sheet from Technical Fibre Products Ltd called Technofire (RTM) 67152B, supplied unexpanded with a thickness of 1.3mm. The lock plate 102 is likewise a sheet material - preferably made of metal such as stainless steel, but stiff enough not to excessively flex under the influence of the compressed spring 98. In this example it is made of 0.9mm thick stainless steel.

With this arrangement, and while the intumescent 100 is unexpanded, the spacers 94 are not softened or deformed, and the spring is compressed by the stiffness of the lock plate (the intumescent 100 may have a hole through it or may be positioned as two pads either side of the spring so that the spring directly acts on the lock plate 102), the intumescent latch 72 is clear of the respective keep 68 in the facing edge of the door 12. However, upon exposure to heat - e.g. a fire, either the intumescent will expand or the spacers will soften, thus allowing either or both of the intumescent 100 and the spring 98 to deflect the lock plate 102 into the keep 68.

Typically the spacer’s glass transition temperature will be chosen to be below the temperature of activation of the intumescent, whereby the spacers 94 will soften first, thus allowing the spring to do the initial deflection. Then, as the temperature increases (due to a fire for example) , the intumescent will expand to backfill a gap between it and the frame’s first flange 118, as shown in Figures 24 to 26, where figure 24 shows the start condition, figure 25 shows the effect of the spacers 94 softening and deforming under the influence of the spring 98 against the lock plate 102, to move the lock plate into the opening 108 of the keep 68, and then Figure 26 showing the back-filling by the intumescent and ultimately a further deflection of the lock plate 102 further into the keep 68, which can even include a bending of the lock plate if the combined forces of the spring and the intumescent overcome the stiffness of the lock plate. See also Figure 23 for this fully extended configuration - Figure 23 is a section through one of the connection bolts 86). These intumescent latches could likewise be incorporated onto the frame of the first embodiment - and the keeps into the door of that first embodiment.

Referring next to Figures 22 and 23, an initial lateral offset of the keep 68 relative to the lock plate 102 is shown. This is to allow for the fact that the door 12 may start to bow in response to a fire before the spacer can soften. This is because of an inevitable temperature difference between the two sides of the door in the event of a fire on one side of the door causing expansion of the relatively hotter side of the door relative to the relatively colder side of the door. Even a small temperature difference of 10 to 20 degrees can cause noticeable bowing. Upon that bowing occurring, the keep 68 will be brought into alignment with the intumescent latch 72 such that upon either the softening of the spacers 94 or expansion of the intumescent 100 the intumescent latch 72 will correctly engage into the keep 68.

In this embodiment the keep has an overhang 136 which can dig into the intumescent 100 to lock the lock plate 102 in the keep 68, thus preventing the warping or bowing of the door from continuing beyond a certain degree - retained by the bolts 97 and screws 96 of the connection bolts 86 of the intumescent latch 72.

With this second embodiment, the frame is stiffer and is thus less likely to buckle in a fire.

Referring finally to Figure 35, an optional levelling frame shroud 138 or fixing extension is shown fixed to the wall between the frame 10 of the doorset and the wall. This optional levelling frame shroud allows the frame 10 to be fixed to a non-level wall surface, such as a stone wall. It can be made of a more flexible material than the frame to allow it to shape closer to the wall’s contours, although in this embodiment it is a similar material. It has an outwardly extending flange to which the frame 10 of the doorset can be affixed - for example using bolts, rivets or welding. In Figure 19, holes 90 for bolts are shown in the frame 10. In addition to allowing a less flat wall to be accommodated, the optional levelling shroud or fixing extension 138 can allow the frame 10 to be fitted to an opening in the wall that is only slightly smaller than the frame, without needing the provision of the side panel of Figures 12 to 16, or similar. The levelling frame shroud or fixing extension may even be a short extension for the frame or a short L bracket - being a single side element rather than necessarily being to the sides and top of the frame, or just one of multiple L brackets to the side. For example a suitable L section similar to that shown can extend the width (or height) of the frame by a few cm to take connections screws further away from an edge of an opening, if needed. The present invention has therefore been described above purely by way of example. Modifications in detail may be made to the invention within the scope of the claims as appended hereto.