GB2458203A

GB2458203A - Ceiling hatch for secure rooms

Info

Publication number: GB2458203A
Application number: GB0903659A
Authority: GB
Inventors: Trevor David Leisk
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-03-04
Filing date: 2009-03-03
Publication date: 2009-09-16
Also published as: GB0903659D0; AU2009200822B2; GB2458018A; AU2009200822A1; GB2458018A9; AU2009200823A1; GB0903660D0

Abstract

A ceiling hatch 60 for a type 1 secure room has a hatch frame and cover. The hatch frame has a rectangular wall member 61 comprising four vertical side walls. At least one flange member 62 extends horizontally outwardly from the lower edge of each side wall. Apertures 68, 25 are provided in the side walls and/or flanges, through which screws 27, 28 can be used to fasten the frame to purlins 53. The hatch cover is a rectangular plate 70, connected by hinges 63 to the hatch frame. Planar strips 64 extend perpendicularly from the top surface of the plate 70. The hatch cover 70 can be locked in its closed position by a lock 73, which may include a micro-switch box. Gas struts 69 may be connected between the hatch frame and cover. The ceiling hatch 60 may be mounted in a support frame 50 that is independently mountable between the purlins of the ceiling. The hatch may also be installed between the studs or noggins of a stud wall.

Description

Ceiling hatch for secure rooms

Technical field.

This invention concerns secure rooms. More particularly, it concerns hatches for use in the ceilings of type 1 (top secret) secure rooms. However, the invention may be used in any room which is not a type 1 secure room but in which a degree of security of access to the space above the ceiling of the room is required. It may also be used as a security door in a stud wall.

Preliminary note.

In this specification, including the claims, "directional" terms (such as "top", "bottom", "side", "underside", "upper", "lower", "above", "upwards", "below", "inwards", "behind", "horizontal", "vertical" and the like) wifi be used in the sense that these terms would have with reference to an embodiment of the invention positioned as shown in Figures 1, 2 and 3 of the accompanying drawings.

Background to the invention.

The ceilings of type 1 secure rooms must resist a breach of the ceiling by a person or by a camera. Where it is necessary to provide access through the ceiling to air conditioning ducts, cables routed in the space above the ceiling, valves and other equipment items, the current practice is to have a rectangular manhole or trapdoor arrangement in the ceiling. A typical trapdoor comprises a square metal plate in a metal frame that is mounted in the ceiling. This type of trapdoor usually covers an aperture in the ceiling which measures about 450 mm by 450 mm. The square metal plate of the trapdoor is almost always held in place by (a) a pair of heavy duty (sturdy) hinges, which are welded to one side of the metal frame, and (b) simple bolts, which are mounted on the opposed side of the metal plate and which are secured in place by padlocks. With this form of trapdoor, the gap between the edge of the trapdoor and its surrounding frame is typically about 2 mm, which means that a miniature camera in the space above the ceiling can take photographs of the room under the ceiling, through that gap. The trapdoor is also heavy, so it is awkward to close and lock, and it has to be opened with particular care to avoid injuring the person who is opening it. In addition, it is unsightly and it is not tamper-evident (that is, no positive signal is generated to indicate an unauthorised opening of the trapdoor).

Disclosure of the invention.

It is an object of thepresent invention to provide an effective, secure ceiling hatch for a type 1 secure room, which may -if desired -include means for generating a signal to indicate that the hatch has been opened.

This objective is achieved with a hatch that is adapted to be mounted in the ceiling of a secure room (if it is to be used as a door, it will be mounted in a wall). The hatch comprises a hatch frame and a hatch cover. The hatch frame is rectangular and is constructed of a rigid material (preferably metal sheet). The frame comprises a rectangular wall member having four side walls, and at least one flange member extending horizontally outwardly from the lower peripheral edge of each side wall of the wall member. Preferably, the flange members extending from the four side walls are contiguous, and form a single flange member which completely surrounds the wall member.

The hatch frame is adapted to be mounted securely in a set ceiling. A typical set ceiling comprises a sheet of plasterboard (generally 12 mm thick) attached to purlins. The purlins usually have a standard spacing, but this invention can be used with any spacing of the ceiling purlins. If the invention is to be used as a door, the studs and noggins of the wall will be spaced to enable thehatch frame to bemounted in the wall. For convenience, the following description will relate to a ceiling mounted form of the invention (which is, of course, the perceived main use of this invention).

A rectangular aperture, just large enough to receive the wall member of the batch frame, is cut into the ceiling between two adjacent purlins. The wall member should be a snug fit between two adjacent purlins of the ceiling, with one side wall of the wall member close to, or touching, one purlin and with the opposed side wall of the wall member close to, or touching, the adjacent purlin. Screws are used to secure the hatch frame in place. Each screw either (a) passes upwardly through a respective clearance hole in a flange member and through the sheet of plasterboard, to be screwed into one of the purlins, or (b) passes horizontally through a clearance hole in a respective side of the wall member, to be screwed into one of the purlins. If it is felt necessary, clearance holes may be provided in both the flange members and the individual sides of the wall member, and the hatch frame may be securely mounted on the purlins using both screws through the flange members and screws through the wall member.

Hinges connected to (welded to, if the hatch frame is constructed of steel) one side of the hatch frame support a rigid, planar, rectangular sheet, constituting the hatch cover. Preferably, the hatch cover is of metal (preferably steel). The hatch cover is a very close fit within the wall member of the batch frame. Preferably the gap between the batch cover and the wall member of the hatch frame is no more than 0.33 mm.

The rectangular cover sheet has elongate planar strips of a rigid material affixed to at least part of the edge regions of its top surface, with one edge of each planar strip being in contact with, and being affixed to, this top surface, and with the plane of each strip being perpendicular to the plane of the rectangular sheet.

Each of these planar strips is thus a partial peripheral wall member on the top of the rectangular sheet. Each such sthp can be conveniently formed using a length of a rigid material (again, preferably metal) which has (for example, by bending or by extrusion) an L-shaped cross-section. Such a length of rigid material has two planar, elongate strips. One of its planar strips can be attached to the upper or top surface of the rectangular sheet, adjacent to a respective edge of the cover sheet (by bonding, by being welded to it, or by screws). The other planar strip of such a length of rigid material then extends at right angles to the plane of the rectangular sheet, to form a peripheral wall member of the hatch cover. These hatch cover wall members, when the hatch is closed, cover the ends of those screws which may have been used to attach the wall member of the hatch frame to the purlins of the ceiling.

A suitable lock is provided to ensure that the hatch can be securely locked when the hatch is closed and the plane of the rectangular sheet of the hatch cover is substantially parallel to the plane of the (or each) flange member of the hatch frame.

Thus, according to the present invention, a batch for use in the ceiling of a type 1 secure room comprises a hatch frame and a hatch cover, characterised in that: a) said hatch frame comprises a rectangular wall member consisting of four planar side walls, the plane of each side wall being vertical, with at least one flange member extending horizontally outwardly from the lowermost edge of each side wall; the dimensions of said hatch frame being such that two opposed side walls of said wall member are a close fit within adjacent purlins of said ceiling; apertures being provided in said side walls, and/or in each flange member or in selected flange members, so that respective screws may be passed through said apertures and be screwed into said purlins; b) said hatch cover comprises a rigid rectangular sheet, one edge of said rectangular sheet being connected to said hatch frame by hinges which are located on, or adjacent to, the lower inside edge of one side wall of said wall member; a respective elongate planar strip of a rigid material extending at right angles from at least part of each edge region of the top surface of said rectangular sheet to form a partial peripheral wall member on the top of said rectangular sheet; and c) said hatch cover includes a lock to lock said hatch cover in a closed position in which the plane of said rectangular sheet is substantially parallel to the plane of said, or each, flange member.

Preferably, a bracing member (for example, a length of a rigid material having an L-shaped cross-section, or a length of a rigid, hollow rod of rectangular cross-section) is also attached to the upper surface of the rectangular sheet of the hatch cover, to enhance its rigidity. Also, preferably, gas struts will be provided so that when the rectangular sheet of the hatch cover is opened, it will move slowly downwards on its hinges. In addition, it is also preferable to use a lock with a micro-switch box of the type described in the specification of my International (PCT) patent application No. PCT/AU2005/001064, which is WIPO Publication No. WO 2006/015404, so that the lock status can be monitored when the hatch is closed.

Although the ceiling hatch of the present invention, as described above, is suitable for use in the ceilings of type 1 (top secret) rooms, in some circumstances it will be advantageous to provide a support frame for the ceiling hatch. In this case, the support frame will be mounted in the ceiling, by being attached, securely, to adjacent purlins of the set ceiling (to ajacent studs and/or noggins in a stud wall if it is intended to be used as an access door in a wall), and the hatch will be mounted within the support frame.

Thus the present invention also encompasses a ceiling hatch which includes a support frame (a) that is mountable in a set ceiling and (b) within which the ceiling hatch can be mounted..

Such a support frame comprises a frame which has a similar construction to the hatch frame of the ceiling hatch of the present invention, namely, a rectangular wall member consisting of four planar, vertical, side walls, with at least one flange member extending horizontally outwardly from the lower edge of each side wall. Again, preferably, the flange members extending from the four side walls of the wall member of the support frame will be contiguous, thereby forming a single flange member which completely surrounds that wall member.

To install the support frame in a set ceiling, a rectangular aperture, just large enough to receive the wall member of the support frame, is cut into the ceiling between two adjacent purlins. The support frame wall member should be a snug fit between two adjacent purlins of the ceiling, with one side wall of the support frame wall member close to, or touching, one purlin and with the opposed side wall of that wall member close to, or touching, the adjacent purlin. Screws will then be used to secure the support frame in place. Each screw will pass either (a) upwardly through a respective clearance hole in a flange member and through the sheet of plasterboard, to be screwed into one of the purlins, or (b) through a countersunk clearance hole in a side wall, to be screwed into one of the purlins.

The dimensions of the wall member of the support frame must be such that the wall member of the ceiling hatch is a close fit within the wall member of the support frame. The wall member of the ceiling hatch will contain apertures -preferably in each side wall of that wall member -through which respective screws may be passed (a) to also pass through clearance apertures in corresponding locations in the wall member of the support frame, and then to be screwed into a purlin of the ceiling, or (b) to be screwed into threaded apertures in corresponding locations in the wall member of the support frame.

Embodiments which include features of the present invention will now be described, by way of example only. In the following description, reference will be made to the accompanying drawings.

Brief description of the drawings.

Figure 1 is a schematic sketch of an end of a type 1 secure room, the ceiling of which includes a hatch constructed in accordance with the present invention.

Figure 2 is a perspective sketch, partly schematic, of one form of ceiling hatch for a type 1 secure room, constructed in accordance with the present invention.

Figure 3 is a partly schematic, partly sectional view of a ceiling hatch and a support frame in which the ceiling hatch is to be mounted.

Detailed description of the ifiustrated embodiments.

Figure 1 is a schematic view of one end of a type 1 secure room that has been fitted with the present invention. This room has double doors 11 and 14. The set ceiling 12 of the room is fitted with a security hatch 13, which is constructed in accordance with the present invention, and which provides access, when required, to the space above the ceiling.

As shown in Figure 3, a set ceiling is constructed by affixing a layer of plaster-board 55 (typically 12 mm thick) to purlins 53. It will be recalled that the typical ceiling maithole or hatch currently in use is a simple rectangular metal structure, secured by "pad-bolts". A prototype ceiling hatch constructed by the present inventor uses a rectangular metal frame and has dimensions approximately 600 mm by 750 mm. The size of the hatch, however, is not important.

The ceiling hatch illustrated in Figure 2 has a frame comprising a rectangular wall member 61 and a flange member 62 which is constituted by contiguous flange members extending horizontally from the lower edges of the four sides of the wall member 61.

Preferably, the dimensions of the wall member 61 are such that two opposed sides of the wall member are a snug fit (a press fit is ideal) between the adjacent purlins 53 of a set ceiling. If the ceiling purlins are spaced apart by a greater distance, at least one of the purlins will be "expanded" sideways by mounting a short plank of wood on the purlin. The thickness of the (or each) plank of wood will be such that the "expanded" purlins are separated by a distance such that the opposed sides of the wall members 61 are a snug fit between a purlin and its adjacent "expanded" purlin, or between two expanded purlins. (Henceforth in this specification, including the claims, the term "purlin" includes an "expanded purlin".) To install the ceiling hatch in a ceiling, a rectangular aperture is cut out of the ceiling between adjacent purlins 53. This aperture has dimensions to receive the wall member 61. A number of countersunk (countersunk on the underside) apertures 25 in the contiguous flange 62 enables respective screws 27 to secure the hatch frame securely in the ceiling. Each screw 27 penetrates the plasterboard sheet 55 to be screwed into a purlin 53. Alternatively, or in addition, the mounting of the hatch frame in the ceiling may be effected using screws 28 which pass througi clearance holes 68 in the wall member 61, to be screwed into a respective purlin 53. In the embodiment shown in Figure 2, apertures 68 are included in each side wall of the wall member 61, and in each flange constituting the contiguous flange 62, so that the ceiling hatch may be mounted in any one of four orientations in the ceiling.

The preferred construction of the hatch frame is with the flange member 62 extending outwardly from all four lower edges of the walls of the wall member 51, as shown in Figures 2 and 3, for the flange 62 acts to prevent distortion of S the shape of the wall member 51. However, the contiguous flange 62 may be replaced with a number of small flanges or "tongues", each optionally containing at least one countersunk aperture 25 to enable the hatch frame to be rigidly mounted in place using the screws 27. If this alternative, and not preferred, construction is adopted, the smaller flanges or tongues must be located (a) to ensure that the wall member 61 retains its rectangular horizontal cross-section, and this cross-section does not become rhomboidal; and (b) to fulfil an incidental benefit of the contiguous flange 62, namely, to cover the solid edges of the aperture which has been cut in the plasterboard 55 to receive the ceiling hatch frame, and to prevent visual access from the space above the ceiling to the room below from any gap that might have been created between the wall member 61 and the cut edge of the plasterboard 55.

A rectangular, planar hatch cover 70, in the form of a rigid rectangular plate, has one of its four edges connected to the hatch frame by hinges 63. (If the hatch frame is constructed using steel plate, the knuckles of the hinges 63 are preferably welded onto the sheet 70 and onto the hatch frame.) Planar strips 64 of a rigid material extend perpendicularly from the top surface of the plate 70, along at least part of each edge of the plate 70. (In the ifiustrated embodiment, the strips 64 extend upwardly from the entire edge of the sheet 70, which is the preferred arrangement.) As noted above, conveniently, these sthps 64 may be created using a length of a rigid material which has an L-shaped cross-section, with one of the two strips of such a length of rigid material bonded to, welded to, or screwed onto the top surface of the cover sheet 70. The peripheral wall (or partial peripheral wall) formed by the strips 64 (a) ensures that the cover sheet 70 is unlikely to bend, and (b) when the hatch cover is closed, provides a covering for the ends of any screws 28 that may have used to secure the hatch frame to a purlin, thereby preventing access to those screws 28 from the space above the ceiling.

An additional strip 65 of a rigid material having an L-shaped cross-section, or a length of a hollow rectangular rod, or other suitable bracing member, has been affixed to the hatch cover sheet 70 to provide further bracing for the hatch cover.

The hatch cover 70 can be constructed to be a very close fit within the hatch frame. For example, if laser cutting is used to cut the contiguous flange member 62 and the cover sheet 70 from the same sheet of heavy gauge steel plate, the "gap" between the edge of the hatch cover 70 and the flange 62 will be 0.33 mm.

This gap size does not permit a miniature camera to be used by a person in the space above the ceiling to photograph the inside of the secure room beneath the ceiling.

From the above description, it will be apparent that if the hatch cover as shown in Figure 2 is constructed using a heavy gauge steel plate, it will weigh a considerable amount. Accordingly, in the illustrated embodiment, gas struts 69 have been provided. Each gas strut 69 has one end connected to a wall of the wall member 61 of the batch frame, and its other end connected to a respective strip 64 extending from the hatch cover, adjacent to one edge thereof. The gas struts 69 ensure that, when the hatch cover is unlocked, the hatch cover will be opened in a controlled manner, with minimal risk of injury to the person opening the hatch.

A handle 71 will normally be provided to assist in the opening and closing of the hatch.

Preferably, the hatch is secured in its closed position by a lock 72 which has an associated micro-switch box 73 of the type described in the specification of my International (PCT) patent application No. PCT/AU2005/001064, which is WIPO Publication No. WO 2006/015404. Most preferably, in type 1 secure rooms, the micro-switch box includes a triple reed switch -for example, a Chubb ("Chubb" is a trade mark) triple reed switch. Normally, a cover (not shown in Figures 2 and 3, but present in Figure 1) will be provided for the region of the hatch frame that contains the micro-switch box 73. The space beside the micro-switch box 73 may be used to house other components.

In the above description of the embodiment of Figure 2, it will be apparent that the preferred material for constructing a ceiling hatch for a type 1 secure room is heavy gauge steel plate. However, for some secure rooms, and if the ceiling hatch is for a room having a lesser security requirement, other materials may be used to construct the ceiling hatch. Such other materials include certain rigid plastics materials.

Figure 3 is a partly schematic, partly sectional view of a combination ceiling hatch and support frame 50.

The support frame 50 comprises a rectangular wall member 51 having four planar, vertical side walls, of a rigid material. A contiguous flange member 52 extends horizontally outwardly from the lower peripheral edge of the wall member 51.

When the hatch is to be used in a ceiling of a type 1 secure room, the four side walls of the wall memberS! and the contiguous horizontal flange member 52 are preferably constructed by welding together lengths of heavy gauge steel plate.

However, the wall member 51 and the flange member 52 may be constructed from other suitable materials -including some rigid plastics materials -if the ceiling hatch is to used in the ceiling of a room with a lower security classification.

Preferably, the dimensions of the support frame are such that two opposed sides of the wall member 51 are a snug fit (a press fit is ideal) between the adjacent purlins 53 of a set ceiling. If the ceiling purlins are spaced apart by a greater distance, at least one of the purlins will be "expanded" by mounting a short plank of wood on the purlin, and the thickness of the (or each) plank of wood will be such that the "expanded" purlins are separated by a distance such that the opposed wall members 51 of the support frame are a snug fit between a purlin and its adjacent "expanded" purlin, or between two expanded purlins. (As noted earlier, in this specification, including the claims, the term "purlin" includes an "expanded purlin".) The dimensions of the support frame 50 are also such that a ceiling batch 60, constructed in accordance with the present invention, fits snugly within the walls 51 of the support frame 50.

To install the support frame 50 shown in Figure 3, a rectangular aperture is cut out of the ceiling between adjacent purlins 53. This aperture has dimensions to receive the support frame 50. A number of countersunk apertures 56 in the flange member 52 enable respective screws 57 to mount the support frame securely in the ceiling. Each screw 57 penetrates the plasterboard sheet 55 to be screwed into a purlinS3.

Although the preferred construction of the support frame 50 is with the flange member 52 extending outwardly from the entire lower edge of the wall member 51, for the flange 52 prevents distortion of the shape of the wall member 51, the flange 52 may be replaced with a number of small flanges or "tongues", each containing at least one countersunk aperture to enable the support frame to be mounted rigidly in place using the screws 57. If this alternative, and not preferred, construction is adopted, the smaller flanges or tongues must be located (a) to ensure that the wall member 51 retains its rectangular horizontal cross-section and this cross-section does not become rhomboidal; and (b) to fulfil an incidental benefit of the contiguous flange 52, namely, to cover the edges of the aperture which has been cut in the plasterboard 55 to receive the support frame, and to prevent visual access to the room below from any gap that might have been created between the wall member 51 and the cut edge of the plasterboard 55.

The ceiling hatch 60 has the same construction as the ceiling hatch shown in Figure 2. When the ceiling hatch 60 has been positioned within the support frame 50, with its wall member 61 a close fit within the wall member 51 of the support frame, screws 67 are passed through countersunk apertures 68 in the wall member 61 to be screwed into respective threaded apertures 58 in the wall member 51 of the support frame. Provided the apertures 58 and 68 are located higher in the walls of the wall members 51 and 61 than the apertures 58 and 68 shown in Figure 3, screws may be passed through countersunk apertures 68 in the wall member 61 and through correspondingly located clearance apertures 58 in the wall member 51, to be screwed into a purlin 53.

As noted earlier in this specification, although intended for use in a ceiling, the hatch of the present invention (including the combination of a ceiling hatch and a support frame) may also be used in a stud wall, with the studs and/or noggins of the stud wall replacing the purlins 53.

Engineers will appreciate that illustrative examples of the present invention have been described above, and that variations of, and modifications to, these embodiments may be made, within the scope of the following claims.

Claims

Claims: A ceiling hatch for use in the ceiling of a type 1 secure room comprises a hatch frame and a hatch cover, characterised in that: a) said hatch frame comprises a rectangular wall member consisting of four planar side wails, the plane of each side wail being vertical, with at least one flange member extending horizontally outwardly from the lowermost edge of each side wail; the dimensions of said hatch frame being such that two opposed side walls of said wall member are a close fit within adjacent purlins of said ceiling; apertures being provided in said side walls, and/or in each flange member or in selected flange members, so that respective screws may be passed through said apertures and be screwed into said purlins; b) said hatch cover comprises a rigid rectangular sheet, one edge of said rectangular sheet being connected to said hatch frame by hinges which are located on, or adjacent to, the lower inside edge of one side wall of said wall member; a respective elongate planar strip of a rigid material extending at right angles from at least part of each edge region of the top surface of said rectangular sheet to form a partial peripheral wall member on the top of said rectangular sheet; and c) said hatch cover includes a lock to lock said hatch cover in a closed position in which the plane of said rectangular sheet is substantially parallel to the plane of said, or each, flange member.
2. A ceiling hatch for a secure room, including a support frame, characterised in that: (a) said support frame comprises a rectangular support frame wall member consisting of four planar side walls, the plane of each side wall of said support frame wall member being vertical, with at least one support frame flange member extending horizontally outwardly from the lowermost edge of each side wall; the dimensions of said support frame being such that two opposed side walls of said support frame wall member are a close fit within adjacent purlins of said ceiling; at least one aperture being provided in each support frame flange member, so that respective screws may be passed vertically upwards through said apertures and be screwed into said purlins; (b) said ceiling hatch comprises a hatch frame and a hatch cover, characterised in that: 1) said hatch frame comprises a rectangular wall member consisting of four planar side walls, the plane of each side wall of said hatch frame wall member being vertical, with at least one flange member extending horizontally outwardly from the lowermost edge of each side wall of said hatch frame wall member; the dimensions of said hatch frame being such that the four side walls of said hatch frame wall member are a close fit within the four side walls of said support frame wall member; apertures being provided in said hatch frame wall member, so that respective screws may be passed through said apertures in said batch frame wall member and then either be screwed into correspondingly located threaded apertures in the wall member of said support frame, or be passed through correspondingly located clearance holes in the wall member of said support frame and be screwed into said purlins; 2) said hatch cover comprises a rigid rectangular sheet, one edge of said rigid sheet being connected to said hatch frame by hinges which are located on, or adjacent to, the lower inside edge of one side wall of said hatch frame wall member; a respective elongate planar strip of a rigid material extending at right angles from at least part of each edge region of the top surface of said rectangular sheet, to form a partial peripheral wall member on the top of said rectangular sheet; and 3) said hatch cover includes a lock to lock said hatch cover in a closed position in which the plane of said rectangular sheet is substantially parallel to the plane of said, or each, hatch frame flange member.
3. A ceiling hatch as defined in claim 1 or claim 2, including a bracing member attached to the upper surface of said rectangular sheet.
4. A ceiling hatch as defmed in claim 3, in which said bracing member is a length of rigid material having an L-shaped cross-section, or is a hollow rectangular rod.
5. A ceiling hatch as defined in any preceding claim, including a pair of gas struts, each gas strut having one end connected to a respective side wall of said hatch frame wall member and the other end connected to one of said elongate planar strips of a rigid material extending from an edge region of the top surface of said rectangular sheet.
6. A ceiling hatch as defmed in any preceding claim, in which said lock includes a micro-switch box, as hereinbefore described.
7. A ceiling hatch as defined in claim 6, in which said micro-switch box includes a triple reed switch.
8. A ceiling hatch as defmed in any preceding claim, in which said at least one flange member extending horizontally outwardly from the lowermost edge of each side wall of said hatch frame wall member comprises a single coirtiguous flange extending around the periphery of the four sides of said hatch frame wall member.
9. A ceiling hatch as defined in claim 2, or as defined in any one of claims 3 to 8 when appended directly or indirectly to claim 2, in which said at least one flange member extending horizontally outwardly from the lowermost edge of each side wall of said support frame wall member comprises a single contiguous flange extending around the periphery of the four sides of said support frame wall member.
10. A ceiling hatch as defined in any preceding claim, installed in a set ceiling of a room.
11. A ceiling hatch as defined in any preceding claim, in which said hatch is installed in a stud wall, and said purlins are replaced by the studs and/or noggins of said stud wall.
12. A ceiling hatch as defined in claim 1 or claim 2, substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings.