GB1565497A - Portable buildings - Google Patents

Description

(54) IMPROVEMENTS RELATING TO PORTABLE BUILDINGS (71) We, PORTAKABIN LIMITED, a British Company of Huntingdon, North Yorkshire, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to portable buildings of the kind which are intended to be transported in a compact pack ready for erection when delivered to a suitable site.

More particularly, the invention is concerned with building constructions formed from one or more units each of which is potentially a complete building with roof, floor and walls, preferably complete with all necessary doors and windows, with appropriate means for assembling such units together if required to form two or more such units into a multi-unit building. Whilst each such unit would normally be provided with four walls, under some circumstances one or both end walls, or one or both side walls, may be omitted entirely to enable the tmits to be joined end-to-end or sideby-side without the interposition of even a partial dividing wall.

It is an object of the present invention to provide such building units in the form of a readily transportable pack incorporating all necessary structural parts.

In accordance with the invention we provide a portable building unit comprising a floor structure, a roof structure and at least one wall structure in the form of a knocked down pack wherein the or each wall structure lies between the floor structure and the roof structure which latter structures are secured together for transportation, the roof structure being provided with lifting stations and the wall structure being secured to the roof structure by a flexible connecting means which allows movement of the wall structure in at least two mutually perpendicular horizontal directions relative to the roof structure extending between an upper region of the wall structure and an adjacent edge of the roof structure, the arrangement being such that the roof structure can be lifted away from the floor structure by lifting means engaged with the roof at said lifting stations, the wall structure being movable by virtue of said flexible connecting means into a vertical position.

Preferably, the wall structure is secured to the roof structure only by said flexible connecting means, at least when the roof structure is lifted so that the wall structure is automatically raised to the vertical position as the roof structure is lifted.

It will be understood that as the roof structure is lifted, the wall structure is lifted initially from the region thereof which is in the pack disposed adjacent to part of the edge of the roof structure at which it is attached by the flexible connecting means until the wall structure is freely suspended from the raised roof structure. Usually, the wall structure will be suspended from that edge of the roof structure to which it is required to be secured in the assembled construction. In such a case the suspended wall structure can be manoeuvred by hand into position on the edge of the floor structure and secured thereto, the roof structure being lowered subsequently into position on the wall structure.

Although such a unit may occasionally include only one wall structure (e.g. because it is to be joined to other units on three sides) it is more usual for the unit to include at least two wall structures. Where two such wall structures constitute the opposed side walls of a rectangular building they can be laid so as at least partially to overlap one another. In such a case as the roof structure is lifted the lower edge of the uppermost wall structure slides on the lowermost wall structure whilst the lower edge of the latter slides over the floor structure, or any other component of the pack which may be mterposed. To avoid damage to the surfaces of the wall structures, the pack preferably includes spacer strips, for example of soft wood, over which the lower edges of the wall structures slide towards the edges of the floor structure.

Where, as is usuaL the unit is of rectangular form in plan view, and the building is provided with longitudinally extending side walls, it is preferred that the wall structures which are attached to the roof structure by means of said flexible members comprise those wall structures which will form the longitudinal walls of the assembled building. Any end walls may be separately stowed within the pack without attachment to the roof structure. Such end walls can be manoeuvred into upright positions separately either manually or with the assistance of lifting gear.

However, in the absence of any such longitudinal side walls, it is alternatively possible for transverse end walls to be so attached.

In this case, if the vertical dimension of the end wall structure permits, the (or each) end wall structure may initially be secured by said flexible connecting means to a longitudinal (side) edge of the roof structure instead of to the end edge thereof. The end wall structure would be secured at a position on the longitudinal edge adjacent to the end edge with which it is to be assembled, and after the roof structure is raised the suspended end wall structure would be swung through 90" into its intended position, the flexible connecting means being partly or wholly disconnected for this purpose.

By using such an arrangement it would be possible for a pair of adjacent end and side wall structures to be secured to, and lifted by, the roof structure.

Where the pack required three or four wall structures, the largest one, or opposed pair, thereof is preferably secured to the roof structure in the manner described above, with the remaining smaller one, or pair, resting on the floor structure for manhandling into the final position with the side wall structures resting on the end wall structures. Normally, the length of the floor structure would be appreciably greater than the combined width of the two end wall structures so that these could be arranged on the floor structure adjacent to the ends at which they are required to be erected and without overlapping one another.However, where necessary they could be arranged to overlap one another Conveniently, any end wall structures can in such a case be fastened to the floor structure by means of angle section uprights used subsequently for securing the end and side wall structures together at the corners of the assembled building.

However, if the remaining wall structure is inconveniently large for man-handling it may be possible for it (or both of them) also to be secured to the roof structure. For example one or two end wall structures could be secured to the roof structure by said flexible connection means either at the appropriate end edge of the latter structure or at an adjacent lateral edge, but with the addition of further releasable attachment means so that as the roof structure is initially raised the end wall structure as a whole is lifed with it. The side wall structures could be secured to the lateral edges of the roof structure at their upper edges only so as to be lifted into vertical positions as the roof structure is lifted and thereafter the attachment means for the end wall structure (or structures) could be released to allow such structures to be lowered by hand into vertical positions.

The flexible connecting means by which each wall structure is attached to the roof structure preferably comprises a pluarlity of spaced straps, for example of nylon or like webbing, so that the wall structure can be moved in three dimensions, ie. both vertically and horizontally m its own plane and also transversely to such plane, to facilitate attachment to the floor structure.

Conveniently, the floor structure includes ledges at each longitudinal edge upon which the side wall structures may rest prior to being secured in such position.

The lifting points of the roof structure may comprise brackets arranged in pairs at the edges thereof and the roof structure preferably includes vertical facia elements at its longitudinal and transverse edges, with such lifting brackets conveniently secured by bolts to the longitudinal facia elements which act as spreaders and enable the roof and wall structures to be lifted by chains without the use of spreader bars.

The lifting brackets may comprise two separable members one of which is bolted directly to the roof structure and the other of which is bolted directly to the floor structure so that such brackets serve to secure the roof and floor structures together ahd enable the whole pack to be lifted by means of such brackets. This arrangement is described and claimed in our copending application no 40287175 (Serial No.

1 565 498).

The floor structure preferably includes a pair of longitudinally extending beams to which one such member of each lifting bracket is bolted to secure the floor and roof structures together in the pack. To assemble the building from the pack, the bolts secur ing said one member of each lifting bracket to the floor structure are removed. If the unit is of the type incorporating legs by means of which its weight is transmitted to the ground, the lifting brackets may most conveniently be bolted to anchorage points provided for the attachment of such legs so that the lifting brackets may be removed entirely after the building is erected to enable the legs to be attached.

Preferably, the packs are capable of being stacked upon one another for transport, and in this case provision may be made for transmitting the weight of a superposed pack directly from the floor structure thereof to the floor structure of the lower pack. In one arrangement, longitudinal beams forming part of the floor structure may extend outwardly beyond the ends of the floor proper and upright frames may be secured to the projecting end portions of such beams so that the floor structure of the superposed pack does not rest on the roof structure of the lower pack. Alternatively, or addition ally, the two members of the lifting brackets may be formed respectively with head and foot elements so that the lower member of a lifting bracket of a superposed pack may rest upon the upper member of a bracket of the lower pack.

The invention also resides in the method of erecting portable building unit comprising a floor structure, a roof structure and at least one wall structure in the form of a knocked down pack in which the wall structure lies between the floor structure and the roof structure, the method comprising securing said wall structure of the roof structure by flexible connecting means ex fending between an upper region of the wall structure and an adjacent edge of the roof structure and lifting the roof structure away from the floor structure so as thereby to raise the wall structure to a vertical position, and thereafter securing the wall structure fixedly to the roof structure and to the floor structure.

The invention will now be described by way of example with reference to the accompanying drawings which illustrate a single embodiment of the invention. In the drawings, FIGURE 1 shows a knocked down pack in end view, FIGURE 2 shows an end portion of the pack in side view, FIGURE 3 illustrates a stage in the erection of the building from the pack, and FIGURE 4 shows a perspective view of the fully erected building unit.

The building unit in accordance with the invention incorporates a prefabricated roof structure 10, a prefabricated floor structure 20, prefabricated side wall structures 30 and 40, and two prefabricated end wall structures 50, only one of which is shown in the accompanying drawings.

The roof structure 10 incorporates vertically disposed longitudinal facia elements 11 and transverse facia elements 12 which add rigiditv to the structure.

The floor structure 20 includes a flat floor proper 21 provided at its longitudinal edges 21a and 21b with angle section members 22 on which the lower edges of the wall structures 30 and 40 are intended to rest.

The floor structure 20 also includes a pair of longitudinally extending beams 23 which are secured together by means of cross members not visible in the accompanying drawings, but similar to the cross member 71 forming part of the frame structure 70 as hereinafter described.

The wall structures 30 and 40 are each complete with all necessary doors as shown at 41 and windows as shown at 42 in Figure 4. Likewise, the end wall structures 50 are also provided with any necessary doors and windows as shown at 52.

In the pack, the end wall structures 50 are each laid separately on the floor structure 20 adjacent to the respective ends at which they are to be erected, and as shown they are conveniently arranged with their height extending transverse. The end wall structures 50 are secured in position of the floor structure 20 by means of angle section members 53 which are used subsequently for securing the end and side wall structures together at the corners of the unit.

As can be seen from Figure 1, the side wall structures 30 and 40 rest on one another on top of the end wall structures 50 and preferably strips of soft wood or the like are arranged to extend transversely between these structures in order to prevent damage thereto. The side and end wall structures are arranged with their outer facse downwards and the side wall structures 30 and 40 are secured to the roof structure 10 by means of flexible straps 33 and 43 extending between the upper edges of the wall structures and the upper edges of the facia elements 11 of the roof structure. The straps are secured at their ends to the inner faces of the wall structures and the facia members.

At two points along its length, each longitudinal facia element 11 is provided with anchorage points 13, (see Figure 4) for lifting brackets 60. Each lifting bracket 60 comprises an upper plate 61 which is bolted directly to the facia element 11 and terminates at its upper edge in an inturned flange 62. An inverted U-shape stirrup 63 has its straight limbs welded to the edges of the upper plate 61 and is adapted to receive a lifting hook as indicated at -64 (Figure 3).

Each lifting bracket 60 further comprises a lower plate 65 which is bolted to a spacer member 66 in the form of a short length of square section tube secured to one of the longitudinal beams 23 of the floor structure. For this purpose, the tube includes end plates formed with bolt holes. The outermost end plate also carries an angle section bar 67 secured to the underside of the angle section member 22 at the edge of the floor 21.

The lower plate 65 of the lifting bracket 60 is bolted to the outermost end plate of the spacer member 66 and at its upper end overlaps the uper plate 61 so as additionally to be secured to the roof structure 10 through the same bolts which secure the upper plate 61. At its lower end, the lower plate 65 is provided with an outwardly directed flange or foot 68 which is adapted to rest on the flange 62 of the upper plate of another similar bracket if the pack is stacked on top of a similar pack.

Such stacking of the packs is further facilitated by the frameworks 70 previously referred to although these may not be necessary in all cases. As can be seen from Figure 2, the longitudinal beams 23 of the floor structure include end portions which project endwise beyond the floor 21 and such portions are joined together by a transversely extending beam 71. Each end portion of the beams 23 carries a pair of angle section plates 72 to which upright posts 73 are secured. Diagonal braces 74 extend between the posts 73 and the cross member 71 to connect these together into a vertical framework. The posts 73 carry plates 75 at their upper ends and preferably such plates have upturned flanges at three of their edges so as to be adapted to re ceive and positively locate the projecting end portions of the longitudinal beams 23 of a superposed pack.The vertical frameworks 70 would normally be removed from the beams 23 after the unit has been erected.

For transport, the packs rest on the longitudinal beams 23 and the feet 68 of the lifting brackets, the whole pack being lift able by means of the stirrups 63. The vertical facia elements 11 and 12 obviate the necessity for using spreader bars between the slings used for this purpose. On delivery, the pack is placed in the desired position and then the lower plates 65 of the lifting bracket 60 are removed so that the pack is supported entirely by the longitudinal beams 23 whilst the upper plates 61 are re-connected to the roof structure. The roof structure 11 is then lifted by means of the stirrups 63 and, as shown in Figure 3, the side wall structures 30 and 40 are thus simultaneously lifted by means of the straps 33 and 34.The lower edge 35 of the side wall structure 30 slides over the uppermost, inner face of the side wall structure 40 and at the same time the lower edge 45 of the side wall structure 40 slides in the opposite direction over the uppermost, inner face of the end wall structures 50.

As mentioned previously, strips of soft wood may be interposed between the wall structures to facilitate this and protect them from damage. Where, as is normally the case, the width of the two end wall panels 50 is in combination less than the length of the floor 21, the space on the floor inbetween the two end wall panels would normally house transversely extending strips of wood or the like to support the middle portion of the side wall structure 40.

As the roof structure 10 is lifted, the side wall structures 30 and 40 automatically assume vertical positions substantially in alignment with the longitudinal edges of the floor 21 and due to the flexibility of the straps 33 and 43 they can readily be manoeuvred onto the angle members 22 and secured to the floor structure in this position. Thereafter, the end wall structures 50 can be removed from the base structure and, because of their smaller size, quite readily lifted into position manually and then secured to the end edges of the floor structure and to the end edges of the side wall structures by means of the angle section members 53. The wall structures then form a rigid box and the roof structure 10 can be lowered into position with the facia elements 11 and 12 lying outwardly of the respective wall structures.

If desired, the upper plates 61 of the lifting bracket 60 can then be removed from the roof structure in order to ensure that no attempt can subsequently be made to lift the entire building by means of the roof structure. However, should it be necessary to lift the entire building, this can be achieved by securing the upper plates 61 of the lifting brackets to the lower anchorage points afforded by the spacer members 66, the plates then being turned around so that the flanges 62 face outwardly. Alternatively, if the unit is of the type which is intended to be supported from the ground through the intermediary of legs, the attachment points 13 and those afforded by the spacer members 66 can be used for the attachment of such legs, which are prefer- ably of telescopic form such as to enable the building to be jacked up after the legs are in position so that the longitudinal beams 23 are clear of the ground and the unit is supported entirely by the legs.

It will be understood that were the units are required to be joined directly in end-toend relation, it would not be possible for the beams 23 to project endwise as shown.

In this case, provision of stacking the packs, if required, may be made entirely through the lifting brackets 60, or upright posts similar to the posts 70 could be supported at the ends of transversely extending members, similar to the spacer members 66, projecting outwardly of the lateral edges of the pack, such transverse members also affording respective foot elements similar to feet 68 to engage the head plate 75 at the upper end of each post 70 of a lower pack.

In the preceding description and accompanying drawings, the building unit is described and shown as having four wall structures. However, as previously mentioned any one or more of such wall structures may be omitted where the unit is intended for joining in full-width end-toend or side-to-side relationship with adjacent similar units. Thus, one or both of the end wall structures 50 may be omitted and/or one of the side wall structures 30 and 40 may be omitted. In a case where a unit is required to have end walls 50 only and no side walls, the two end walls could be connected to the roof structure 10 by means of flexible straps so that such walls are raised to the vertical position when the roof structure is lifted.This could be achieved by arranging the upper edge of each end wall structure at a position adjacent to the appropriate end edge of the floor structure 20, with flexible straps connecting the upper edge of each end wall structure to the respective transverse facia elements 12. In this case, the end wall structures would be lifted by the roof structure into substantially their desired positions relative to the base structure in the same manner as has been described in relation to the side wall structures in the embodiment illustrated.

On the other hand, it may in some instance be more convenient for the end wall structures to be laid upon the floor structure in the manner illustrated in the accompanying drawings, i.e. with their heights extending transverse to the length of the floor structure. In this case, the upper edge of one end wall structure would preferably be arranged adjacent to one end of one of the longitudinal facia elements 11, and the upper edge of the other end wall structure would be arranged adjacent to the opposite end of the opposite longitudinal facia element. The two end wall structures would then be secured to the respective facia elements by means of flexible straps similar to those previously described so that when the roof structure 11 is lifted the two end wall structures would be raised into vertical positions in which they extend generally transversely to their intended positions.Thereafter, by releasing one or more straps so as to leave each end wall structure supported by only a single strap, the wall structures would then be swung in a vertical plane through 90C into their desired positions at opposite ends of the floor structure.

It will also be possible to arrange one end wall structure in this manner together with one side wall structure in the manner previously described in a case where the unit is to be provided with a single side wall and single end wall.

In a further alternative arrangement, it would be possible to dispose one or two end wall structures 50 on top of the side wall structures 30 and 40, such end wall structures being secured to the roof structure 10 at both their top and bottom edges so as to be lifted together with the roof structure 10 when the side wall structures 30 and 40 are raised to their vertical positions in the manner shown in Figure 3. Thereafter, the lower edge of the, or each, end wall structure would then be released from the roof structure to enable to end wall structure itself to be swung downwardly into a vertical position between the already vertical side wall structures.

WHAT WE CLAIM IS:- 1. A portable building unit comprising a floor structure, a roof structure and at least one wall structure in the form of a knocked down pack wherein the or each wall structure lies between the floor structure and the roof structure which latter structures are secured together for transportation, the roof structure being provided with lifting stations and the wall structure being secured to the roof structure by a flexible connecting means which allows movement of the wall structure in at least two mutually horizontal directions relative to the roof structure, the flexible connecting means extending between an -upper region of the wall structure and an adjacent edge of the roof structure, the arrangement being such that the roof structure can be lifted away from the floor structure by a lifting means engaged with the roof at said lifting stations, the wall structure being movable by virtue of said flexible connecting means into a vertical position.

2. A portable building unit according to Claim 1 wherein the wall structure is secured to the roof structure only by said flexible connecting means, at least when the roof structure is lifted so that the wall structure is automatically raised to the vertical position as the roof structure is lifted.

3. A portable building unit according to Claim 1 or Claim 2 wherein the or each wall structure is connected by said flexible connecting means to that edge of the roof structure to which it is required to be secured in the assembled construction.

4. A portable building unit according to any one of the preceding claims including

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (29)

**WARNING** start of CLMS field may overlap end of DESC **. similar to the posts 70 could be supported at the ends of transversely extending members, similar to the spacer members 66, projecting outwardly of the lateral edges of the pack, such transverse members also affording respective foot elements similar to feet 68 to engage the head plate 75 at the upper end of each post 70 of a lower pack. In the preceding description and accompanying drawings, the building unit is described and shown as having four wall structures. However, as previously mentioned any one or more of such wall structures may be omitted where the unit is intended for joining in full-width end-toend or side-to-side relationship with adjacent similar units. Thus, one or both of the end wall structures 50 may be omitted and/or one of the side wall structures 30 and 40 may be omitted. In a case where a unit is required to have end walls 50 only and no side walls, the two end walls could be connected to the roof structure 10 by means of flexible straps so that such walls are raised to the vertical position when the roof structure is lifted.This could be achieved by arranging the upper edge of each end wall structure at a position adjacent to the appropriate end edge of the floor structure 20, with flexible straps connecting the upper edge of each end wall structure to the respective transverse facia elements 12. In this case, the end wall structures would be lifted by the roof structure into substantially their desired positions relative to the base structure in the same manner as has been described in relation to the side wall structures in the embodiment illustrated. On the other hand, it may in some instance be more convenient for the end wall structures to be laid upon the floor structure in the manner illustrated in the accompanying drawings, i.e. with their heights extending transverse to the length of the floor structure. In this case, the upper edge of one end wall structure would preferably be arranged adjacent to one end of one of the longitudinal facia elements 11, and the upper edge of the other end wall structure would be arranged adjacent to the opposite end of the opposite longitudinal facia element. The two end wall structures would then be secured to the respective facia elements by means of flexible straps similar to those previously described so that when the roof structure 11 is lifted the two end wall structures would be raised into vertical positions in which they extend generally transversely to their intended positions.Thereafter, by releasing one or more straps so as to leave each end wall structure supported by only a single strap, the wall structures would then be swung in a vertical plane through 90C into their desired positions at opposite ends of the floor structure. It will also be possible to arrange one end wall structure in this manner together with one side wall structure in the manner previously described in a case where the unit is to be provided with a single side wall and single end wall. In a further alternative arrangement, it would be possible to dispose one or two end wall structures 50 on top of the side wall structures 30 and 40, such end wall structures being secured to the roof structure 10 at both their top and bottom edges so as to be lifted together with the roof structure 10 when the side wall structures 30 and 40 are raised to their vertical positions in the manner shown in Figure 3. Thereafter, the lower edge of the, or each, end wall structure would then be released from the roof structure to enable to end wall structure itself to be swung downwardly into a vertical position between the already vertical side wall structures. WHAT WE CLAIM IS:-

1. A portable building unit comprising a floor structure, a roof structure and at least one wall structure in the form of a knocked down pack wherein the or each wall structure lies between the floor structure and the roof structure which latter structures are secured together for transportation, the roof structure being provided with lifting stations and the wall structure being secured to the roof structure by a flexible connecting means which allows movement of the wall structure in at least two mutually horizontal directions relative to the roof structure, the flexible connecting means extending between an -upper region of the wall structure and an adjacent edge of the roof structure, the arrangement being such that the roof structure can be lifted away from the floor structure by a lifting means engaged with the roof at said lifting stations, the wall structure being movable by virtue of said flexible connecting means into a vertical position.

2. A portable building unit according to Claim 1 wherein the wall structure is secured to the roof structure only by said flexible connecting means, at least when the roof structure is lifted so that the wall structure is automatically raised to the vertical position as the roof structure is lifted.

3. A portable building unit according to Claim 1 or Claim 2 wherein the or each wall structure is connected by said flexible connecting means to that edge of the roof structure to which it is required to be secured in the assembled construction.

4. A portable building unit according to any one of the preceding claims including

two such wall structures which constitute the opposed side walls of a rectangular building, in the pack, such two side wall structures being laid so as at least partially to overlap one another.

5. A portable building unit according to Claim 4 wherein one or more additional end wall structures are separately stowed within the pack.

6. A portable building unit according to any one of Claims 1 to 3 wherein the or each such wall structure comprises a transverse end wall for a iectangular building.

7. A portable building unit according to any one of the preceding claims wherein at least one such wall structure is attached to the roof structure by means of said flexible members extending between the upper edge of said wall structure and the corresponding edge of the roof structure to which the wall structure is required to be secured when assembled.

8. A portable building unit according to any one of the preceding claims wherein at least one such wall structure is attached to the roof structure by means of said flexible members extending between the upper edge of said structure and an edge of the roof structure adjacent to the edge thereof to which the wall structure is required to be secured when assembled.

9. A portable building unit according to Claim 5 wherein the or each end wall structure is fastened to the floor structure at least partially by means of angle section members intended subsequently for use in securing the end and side wall structures together at the corners of the assembled building.

10. A portable building unit according to any one of Claims 1 to 3 further comprising one or two end wall structures secured to the roof structure by flexible connection means at their upper edges and additionally secured to the roof structure at their lower edges by releasable attachment means so that when the roof structure is initially raised the or each end wall structure is lifted with it while the or each side wall structure is raised to its vertical position.

11. A portable building unit according to any one of the preceding claims wherein the flexible connecting means comprises a plurality of spaced straps so that the wall structure when suspended thereby can be moved both vertically and horizontally in its own plane and also transversely to such plane.

12. A portable building unit according to any one of the preceding claims wherein the floor structure includes ledges at each longitudinal edge at which a side wall structure is required to be disposed in the assembled building so that the such side wall structure may rest upon such ledge prior to being secured in position.

13. A portable building unit according to any one of the preceding claims wherein spacer strips are provided within the pack over which the lower edge of the or each wall structure can slide as it is lifted to its vertical position when the roof structure is raised.

14. A portable building unit according to any one of the preceding claims wherein the lifting points of the roof structure com- prise brackets arranged in pairs at opposed edges thereof.

15. A portable building unit according to Claim 14 wherein the roof structure includes vertical facia elements at its longitudinal and transverse edges.

16. A portable building unit according to Claim 15 wherein the lifting brackets are secured to the longitudinal facia elements of the roof structure.

17. A portable building unit according to any one of Claims 14 to 16 wherein said lifting brackets comprise two separable members, one of which is bolted directly to the roof structure and the other of which is bolted directed to the floor structure so that such brackets serve to secure the roof and floor structures together.

18. A portable building unit according to Claim 17 wherein the building is of the type incorporating two opposed pairs of legs by means of which its weight is to be transmitted to the ground, and the lifting brackets are secured to anchorage points provided on the floor and roof structures for the attachment of such legs.

19. A portable building unit according to Claim 17 or Claim 18 wherein the floor structure includes a pair of longitudinally extending beams to which one such member of each lifting bracket is bolted to secure the floor and roof structures together in the pack.

20. A portable building unit according to any one of the preceding claims wherein the pack is adapted to be stacked upon another similar pack for transport, provision being made for transmission of the weight of a superposed pack directly from the floor structure thereof to the floor structure of the lower pack.

21. A portable building unit according to Claim 20 as appendant to Claim 19 wherein the longitudinal beams which form part of the floor structure extend outwardly beyond the ends of the floor proper and upright frames are secured to the projecting end portions of such beams so that the floor structure of the superposed pack-does not rest on the roof structure of the lower pack but is supported by such frames.

22. A portable building unit according to Claim 20 or 21 as appendant to Claim 17 wherein the two members of the lifting brackets are formed respectively with head and foot elements so that the lower member of a lifting bracket of a superposed pack may rest upon the upper member of a bracket of the lower pack in load transmitting relation thereto.

23. A method of erecting a portable building unit claimed in any one of the claims 1 to 22 comprising securing said wall structure to the roof structure in the said pack by flexible connecting means extending between an upper edge of the wall structure and an adjacent edge of the roof structure and lifting the roof structure away from the floor structure so as thereby to raise the wall structure to a vertical position, and thereafter securing the wall structure fixedly to the roof structure and to the floor structure.

24. A method according to Claim 23 wherein the wall structure whilst suspended from the roof structure is fixedly secured to the floor structure and thereafter the roof structure is lowered into position on the wall structure and fixedly secured thereto.

25. A method according to Claim 23 or 24 wherein two opposed side wall structures are simultaneously raised to the vertical position when the roof structure is lifted, said two side wall structures at least partially overlapping one another so that as the roof structure is lifted the lower edge of the uppermost wall structure slides on the lowermost wall structure whilst the lower edge of the latter slides over the floor structure or any other component of the pack interposed between the lower wall structure and the floor structure.

26. A method according to Claim 24 or 25 wherein an end wall structure is secured to the roof structure by said flexible connecting means in such a manner as to be lifted to a vertical position in which it extends transversely to its intended position in the erected building and is thereafter swung about a vertical axis into its intended position with the flexible connecting means partly or wholly disconnected.

27. A method according to any one of the preceding claims wherein the pack further includes an end wall structure which is secured to the roof structure by said flexible connection means at its upper edge and is additionally secured to the roof structure at its lower edge by releasable attachment means so that when the roof structure is lifted the end wall structure is lifted with it and is subsequently swung downwardly to a vertical position upon release of said attachment means.

28. A portable building unit substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

29. A method of erecting a portable building unit substantially as hereinbefore described.