[0001] This invention relates to a roof structure for a portable building unit.
[0002] The portable building unit is factory assembled and self-contained, designed for
delivery to a prepared site in an assembled condition complete with floors, walls,
and, preferably, all windows, doors and internal fittings. Such units may be assembled
together to form a multi-unit building, provision for coupling the units together
in the desired arrangement being built into each unit before the unit leaves the factory,
so that the only assembly work required on site is that of coupling units together
where it is desired to form a multi-unit building.
[0003] In some cases the units will include end walls as well as side walls, but alternatively,
one or more of such end or side walls may be omitted to permit full width linking
of the units. Such a unit building will be described hereinafter as "of the kind specified".
[0004] An object of the invention is to provide a new and improved roof structure for a
building unit of the kind specified.
[0005] According to one aspect of the invention, we provide a roof structure for a building
unit of the kind specified comprising a pair of spaced parallel roof beams, interconnected
by a plurality of transversely extending roof joists, at least one roof panel supported
by the roof joists and the or each roof panel comprising an external skin of metal,
an internal skin and an infilling therebetween.
[0006] The infilling may comprise thermally insulating material.
[0007] The external skin of metal may comprise plastics coated steel.
[0008] The internal skin may comprise metal foil and may comprise a paper/foil laminate.
[0009] The infilling may be bonded to the external skin.
[0010] The infilling may comprise a rigid foamed or expanded plastics material and preferably
comprises foamed polyurethane.
[0011] The transversely extending roof joists may be disposed at a level so that the top
surface thereof is substantially at or above the level of the top surface of the roof
beams.
[0012] Preferably, the transversely extending roof joists are each disposed at a level which
increases from one end of the roof beams towards the other so as to provide a sloping
roof.
[0013] The roof beams may each have a flange at or adjacent their upper surface which extends
inwardly towards the other roof beam and the transversely extending roof joists may
be provided with a recess at opposite ends thereof to accommodate said inwardly directed
flanges of the roof beams.
[0014] By providing the or each roof panel as an external skin of metal, with thermally
insulating material sandwiched between the external skin and the internal skin, the
roof structure may be regarded in practical terms as "permanent" in that the roof
structure has a relatively high tolerance to damage, provides long term weather and
pollution durability, resists solar gain and degradation and resists dynamic and static
loads.
[0015] The external skin may extend as a one-piece skin over the full length of the roof
structure from one end of a roof beam to the opposite end thereof.
[0016] The or each roof panel may be provided with a peripheral frame of material more rigid
than the infilling for example softwood, and may be provided with intermediate spacers
or studs of material more rigid than the infilling.
[0017] The roof structure may be provided with facia around the whole of its periphery,
the facia having upper and lower edges at a constant horizontal level throughout the
periphery.
[0018] The provision of such a facia provides the roof structure with a visual appearance
of the roof panel or panels being horizontal, even though the roof panels are sloping
since the roof panels are hidden by the facia which is level.
[0019] The facia may conceal a rainwater gutter at the lower end of the roof structure.
[0020] A suspended ceiling may be suspended from the roof joists, the length of the suspension
means varying along the length of the roof structure so as to provide a level ceiling
despite the varying height of the roof joists.
[0021] According to another aspect of the invention, we provide a building unit of the kind
specified provided with a roof structure according to the first aspect of the invention.
[0022] The building unit may comprise a rigid frame carrying wall and floor panels, the
frame comprising a rectangular floor sub-frame comprising a pair of spaced parallel
floor beams connected together by transversely extending floor joists, a plurality
of vertical columns extending upwardly from the floor sub-frame and carrying the roof
structure.
[0023] At least one side or end of the frame may be provided with at least one panel to
provide an end or side wall, the or each panel comprising a structural sandwich comprising
an outer metal sheet and an inner sheet sandwiching therebetween an infilling.
[0024] The infilling of the or each end or side wall panel may be bonded to the outer sheet
and may comprise thermally insulating material. The infilling may be a rigid foamed
or expanded plastics material, and preferably comprises foamed polyurethane.
[0025] The or each wall panel may comprise an external skin of plastics coated steel and
an internal skin of hardboard, plasterboard, or the like, for example 9mm thick plasterboard,
on a wooden frame and infilled with rigid polyurethane foam.
[0026] The internal skin of the or each wall panel may be clad internally with plasterboard
providing a fire resistance.
[0027] The roof structure may comprise a welded steel frame comprising channel roof beams
and channel roof joists.
[0028] The floor sub-frame may comprise a welded steel frame comprising channel side beams,
channel joists and may have two steel runners.
[0029] At least one floor panel may be supported on the floor sub-frame.
[0030] The columns may each comprise a steel angle member fastened to the floor sub-frame
and to the roof structure.
[0031] According to a third aspect of the invention, we provide a building unit according
to the second aspect of the invention stacked on top of another building unit of the
kind specified.
[0032] The other unit may be similar to the building unit of the second aspect of the invention
except for the absence of a roof panel or the presence of a roof panel of a different
construction.
[0033] A facia may be provided between the upper and lower units to protect the roof frame
of the lower unit.
[0034] According to a fourth aspect of the invention, we provide two building units each
according to the second aspect of the invention and connected together in side-by-side
or end-to-end relationship.
[0035] If desired, the building units of the fourth aspect of the invention may each be
stacked on top of one or two stacked other building units of the kind specified to
form a two or three storey building respectively. Each of the other building units
may be similar to the building units of the second aspect of the invention except
for the absence of a roof panel or the presence of a roof panel of different construction.
[0036] The invention will now be described in more detail, by way of example, with reference
to the accompanying drawings, wherein:-
FIGURE 1 is a side elevation of a portable building unit embodying the invention;
FIGURE 2 is an end elevation seen in the direction of the arrow A in Figure 1;
FIGURE 3 is an end elevation looking in the direction of the arrow B in Figure 1;
FIGURE 4 is a section on the line 4-4 of Figure 2;
FIGURE 5 is a section on the line 5-5 of Figure 4; and
FIGURES 6 and 7 are fragmentary cross-sectional views to an enlarged scale on the
lines 6-6 and 7-7 respectively of Figure 2.
[0037] Referring to the drawin gs, there is illustrated
a portable building unit intended to be linked to a similar building unit in side-by-side
relationship. The building unit is of generally rectangular box-like configuration
and comprises a floor structure 10, a roof structure 11, a pair of end walls 12
a, 12
b and a single side wall 13. No side wall is provided on the side of the unit which
is to be linked to the similar unit.
[0038] If desired, a portable building unit embodying the present invention may comprise
a single one of the building unit illustrated and in this case the building unit would
be identical to the unit illustrated except that a second side wall, opposite to the
side wall 13, would be provided.
[0039] It will also be appreciated that if desired, a building construction embodying the
invention may comprise three or more building units, the building units may be linked
together in side-by-side relationship or end-to-end relationship or any desired combination
of such arrangements.
[0040] In each case, if desired, appropriate end or side walls is or are omitted from the
linked-together units.
[0041] Alternatively, if desired, when two, or more than two, of the building units are
linked together, each building unit may be provided with all its sides and end walls
but with openings or doors provided in adjacent walls to permit intercommunication
between the units. In certain circumstances it may be desired to provide a building
construction comprising two or more units but with no communication between the units,
although communication may be provided by way of a relatively small opening or merely
by way of a window.
[0042] In all the above cases however, the building unit or units concerned are identical
to the unit to be described hereinafter, except for the differences identified above,
namely the presence or absence of the relevant side and/or end walls.
[0043] If desired, one or more building units embodying the invention may be stacked on
a building unit or units which are similar, except for the absence of or a different
construction of roof panel hereinafter to be described.
[0044] Each building unit comprises a rigid steel frame upon which floor, wall, roof and/or
ceiling panels are mounted. The frame comprises a floor sub-frame 14 and a roof sub-frame
15 which comprises part of a roof structure. The sub-frames are interconnected by
vertical columns 16. The floor sub-frame 14 is a welded construction and comprises
a pair of parallel side beams 20 of channel configuration having inturned lips 21
at the free ends of the limbs of the channel. The side beams 20 are connected together
by channel configuration end joists 22 and intermediate joists 23. The end joists
22 have an inturned lip at the free ends of both the limbs of the channel, whilst
the intermediate joists 23 hve an inturned lip only at the free end of the upper limb
of the channel. A portion (not shown) is cut out from the upper corner of each joist
23 to provide a recess to accommodate the top limb and downwardly turned lip 21 of
the side beams 20. A pair of channel section runners 25 are welded to the underside
of the joists 22, 23.
[0045] A floor deck comprising wood particle board in the form of panels 26 is fastened
to the joists 22, 23 and side beams 20 with an underdrawing of bitumen-impregnated
fibreboard, and mineral fibre insulation is laid between the joists on top of the
underdrawing 27. If desired, the floor deck may be of other suitable construction,
for example the panels 26 may comprise plywood.
[0046] The connection between the side beams 20 and end joists 22 comprises an angle section
member to the lower end of which is welded a gusset plate which overlies, and is welded
to, the upwardly facing surface of the lower limb of the beam 20 within the upturned
lip 21. The upper and lower limbs of the end joists 22 are cut away to accommodate
the end of the beam 20 and the web part of the end joist is welded to one of the gusset
plate, whilst the oth er limb is welded to the web
of the beam 20.
[0047] The intermediate joists 23 are welded directly to the side beams 20, 20
a and again have a portion cut out from the upper corner to accommodate the top limb
and downwardly turned lip 21
a of the side beams.
[0048] The roof structure comprises spaced parallel side beams 40 of channel configuration
having inturned lips 39 at the free ends of the limbs of the channel. The roof side
beams 40 are connected together by channel end joists 41 having inturned lips at the
free ends of the limbs of the channel, and intermediate joists 42 which are welded
to the side beams 40 in a similar manner that the joists 22, 23 are welded to the
side beams of the floor frame. Again, appropriate cut-outs 38 provide recesses at
the upper corners of the joists, and the connection between the roof beams 40 and
the end joists 41 uses an angle member and gusset plate as described in connection
with the floor sub-frame.
[0049] The roof structure differs from the floor sub-frame in that the joists 41 and 42
are arranged at a different level along the length of the roof beams 40, as best shown
in Figure 4. More particularly, at the left hand end of Figure 4, hereinafter referred
to as the low end L, the end roof joist 41 has the upper surface of its upper limb
41
a slightly below the upper surface of the top limb of the roof beam 40, whilst at the
opposite end of the roof structure, hereinafter referred to as the high end H, the
end roof joist 41 projects above the top of the roof beams 41 by approximately half
of its height, whilst the intermediate roof joists 42 are disposed at intermediate
heights to provide a rectilinear gradient between the end roof joists.
[0050] In addition, the spacing of the joists is different in that the distance between
two joists in the roof structure is occupied by three joists in the floor frame.
[0051] If required, the roof beams 40 may be bowed before being internally and externally
clad, as hereinafter described, so that when they are subjected to the static load
imposed by the cladding, they straighten out.
[0052] Plasterboard ceiling panels (not shown) may be suspended by clips comprising a one-piece
cold rolled section clipped to the lower limb of the associated roof joist, the length
of the clips varying from roof joist to roof joist to accommodate the different level
of roof joists whilst providing a horizontal ceiling. If desired, other material may
be used for the ceiling panels such as mineral fibre board. If desired, such suspended
ceilings may be installed on site.
[0053] A roof deck 50 is provided and supported on the roof joists 41, 42. The roof deck
comprises a single panel which extends over the whole length of the roof structure
from the high end to the low end and over the whole width of the roof structure. The
roof panel comprises a one-piece polyurethane foamed filled sandwich panel comprising
external skin of plastic coated galvanised mild steel sheet 51 of desired profile.
Bonded by suitable adhesive to the internal surface of the steel skin 51 is a softwood
perimeter frame 52 and intermediate studs of high density profiled foam/ply composite
(not shown). The panel has an internal skin 53 of foil faced building paper and injected
therebetween is rigid polyurethane foam 54 which is bonded to the internal surface
of the steel skin 51 and to the internal surface of the foil faced building paper
53. The plastics coated steel sheet may extend as a single sheet over the whole width
of the panel or comprise a plurality, for example three, sheets, each of whch extend
over the full length of the roof structure from the high end to the low end but which
are disposed in side-by-side relationship with edge corrugations which overlap and
are sealed together by an interposed bead of elastomeric material.
[0054] The roof panel is fastened to the joists 41, 42 by wood screws driven upwardly through
apertures in the joists and into the inter mediate
studs of the roof panel.
[0055] If desired, the roof panels may be made of different material, for example the infilling
may be made of any suitable thermal insulating material and the peripheral frame may
be made of any other suitable material than softwood. The internal skin may be made
of a steel lining instead of the foil faced building paper and the external surface
may be made of other metal such as aluminium.
[0056] As best shown in Figure 5, an infill 60, comprising a plywood panel having laminated
thereto foamed insulation material, is spaced above the one roof beam 40 provided
with the side wall 13 and hence there is a gap between the infill and the beam, which
varies along the length of the beam. A suitable weatherproofing membrane material,
such as Hypalon, is provided to cover the infill 60 and the top of the panel which
provides the side wall 13 to form a seal with the roof panels and completes the insulation,
to prevent cold bridging and possible condensation problems. At each side of the roof
panel a steel flashing, not shown, is provided over the top of the side walls and
the end corrugation of the roof panel. Where the unit is disposed side-by-side with
an identical unit, a suitable flashing is provided to extend over the adjacent end
corrugations of the end panels of the units.
[0057] The roof structure and floor sub-frame described hereinbefore are interconnected
in spaced parallel relation by columns 16 which are bolted to the side beams 20 and
40 of the floor sub-frame and roof structure. The columns at the high and low end
of the building unit are of the same height, the slope of the roof being provided
by the different level of the roof joists 41, 42. In the present example, the slope
of the roof is approximately 1° to ensure positive water shedding and avoiding the
risk of water pooling on the roof. If desired, other slopes may be used but it is
preferred that the slopes exceed one in sixty.
[0058] Each end wall 12
a, 12
b, and the side wall 13 is provided by a single structural panel comprising an outer
plastics coated galvanised mild steel sheet 70 bonded to a softwood frame 71 with
hardboard or 9mm thick plasterboard internal panelling 72 nailed to the frame 71 with
a rigid polyurethane foam infilling 73 therebetween. An internal lining of 12.5mm
thick fibre reinforced plasterboard may be bonded to the 9mm thick plasterboard and
also nailed to the frame.
[0059] The frame for each side and end wall panel comprises top and bottom rails interconnected
by vertical end rails with intermediate vertical rails therebetween. The spacing between
the rails is such that every rail is located at the junction between adjacent sheets
of the plastics coated steel panel. The steel sheets are connected together by interlocking
double folded seams as described in our previous Patent Specification No. 1,520,272.
[0060] The vertical end frame members are secured to the vertical columns 16 by screws driven
from the interior of the unit and the top and bottom rails are nailed to the associated
side beams 20, 40 of the floor sub-frame and roof structure or end joist members thereof.
[0061] A facia arrangement 80 is shown at the high end of the unit and comprises a facia
panel 81 and a lipped channel configuration facia mounting element 82, screwed to
a wall panel 83, screwed to an associated roof joist 41. The facia panel 81 is maintained
in the element 82 by its own weight and an adhesive sealing strip which locates it
against the back faces of the lipped channels. At the low end, the unit is provided
with a facia arrangement 84 comprising a facia panel 85 identical with the panel 81
and a facia mounting element 86 of such configuration as to accommodate a concealed
gutter 87, and which is fixed to the peripheral frame of the roof panels so that the
upper edge of the facia panel 85 is in the same horizontal plane as the upper edge
of the facia panel 81. In addition, a facia panel 88 of the same configuratio n as
the panels 81 extends along the side wall 13 provided with the wall panel and thus
masks the fall in height of the roof. This longitudinally extending facia panel 88
is mounted on the unit by facia mounting elements, identical to the elements 82, which
are fixed to the ply/foam infill 60.
[0062] Where the building unit is provided with a wall panel on both long sides, then of
course a further facia panel assembly, identical to the panel assembly 88, 89, is
provided on both sides of the building unit.
[0063] Where the building units are connected together in end-to-end relationship, then
an appropriate facia element is omitted and suitable ridge or valley gutter components
provided.
[0064] Other details of the building unit and its connection or stacking to similar units
are described in our published specification No. 2,084,213B except that instead of
the HYPALON (Registered Trade Mark) sheeting being folded around the ends of the peripheral
frames and associated beams 40, there are provided metal trims and flashings.
[0065] Where the building unit above described is to be stacked on one similar unit, or
two, stacked similar units, to provide a top storey of a two or three storey building,
respectively, the or each similar building unit does not have a roof panel as described
above but is preferably provided with a temporary weatherproof roof comprising a panel
with a weatherproof membrane which affords protection in storage and during transport
until a unit with a roof panel as described above is stacked thereon. The panel comprises
a particle board decking fastened to cold formed second members with a membrane to
prevent ingress of moisture.
[0066] The features disclosed in the foregoing description, or the accompanying drawings,
expressed in their specific forms or in terms of a means for performing the disclosed
function, or a method or process for attaining the disclosed result, or a class or
group of substances or compositions, as appropriate, may, separately or in any combination
of such features, be utilised for realising the invention in diverse forms thereof.
1. A roof structure for a building unit comprising a pair of spaced parallel roof
beams, interconnected by a plurality of transversly extending roof joists, at least
one roof panel supported by the roof joists and the or each roof panel comprising
an external skin of metal, an internal skin and an infilling therebetween.
2. A structure according to Claim 1 wherein the external skin comprises plastic coated
steel.
3. A structure according to claim 1 or claim 2 wherein the internal skin comprises
metal foil.
4. A structure according to any one of the preceding claims wherein the transversely
extending roof joists are disposed at a level so that the top surfaces thereof are
substantially at or above the level of the top surfaces of the roof beams.
5. A structure according to any one of the preceding claims wherein the transversely
extending roof joists are each disposed at a level which increases from one end of
the roof beams towards the other so as to provide a sloping roof.
6. A structure according to any one of the preceding claims wherein the roof beams
each have a flange at or adjacent their upper surface which extends inwardly towards
the other roof beam, and the transversely extending roof joists are provided with
a recess at opposite ends thereof to accommodate said inwardly directed flanges of
the roof beams.
7. A structure according to any one of the preceding claims wherein the external skin
extends as a one piece skin over the full length of the roof structure from one end
of the roof beams to the opposite end thereof.
8. A structure according to any one of the preceding claims wherein the or each roof
panel is provided with a peripheral frame of material more rigid than the infilling.
9. A structure according to any one of the preceding claims wheein
the roof structure is provided with a facia around the whole of its periphery, the
facia having upper and lower edges at a constant horizontal level throughout the periphery.
10. A structure according to Claim 5 or any one of Claims 8 to 7 when appendant to
Claim 5 wherein a suspended ceiling is suspended from the roof joists by suspension
means, the length of the suspension means varying along the length of the roof structure
so as to provide a level ceiling despite the varying height of the roof joists.
11. A building unit having a roof structure according to any one of claims 1 to 18.
12. A unit according to claim 11 wherein the building unit comprises a rigid frame
carrying wall and floor panels, the frame comprising a rectangular floor sub-frame
comprising a pair of spaced parallel floor beams connected together by transversely
extending floor joists, a plurality of vertical columns extending upwardly from the
floor sub-frame and carrying the roof structure.
13. A unit according to claim 12 wherein at least one side or end of the frame is
provided with at least one panel to provide an end or side wall, the or each panel
comprising a structural sandwich comprising an outer metal sheet and an inner sheet
sandwiching therebetween an infilling.
14. A unit according to Claim 13 wherein the or each wall panel comprises an external
skin of plastics coated steel and an internal skin of hardboard or plasterboard on
a wooden frame and infilled with rigid polyurethane foam.
15. A unit according to any one of Claims 11 to 14 wherein the roof structure comprises
a welded steel frame comprising channel roof beams and channel roof joists.
16. A unit according to Claim 12 or any one of Claims 13 to 15 where appendant to
Claim 12 wherein the floor sub-frame comprises a welded steel frame comprising channel
side beams and channel floor joists.