Various panels of this type are known. There is, however, a need for an improved panel which will ensure the integrity of a sealed joint between adjacent panels on assembly.

Statements of Invention According to the invention, there is provided an insulated panel comprising :- an external sheet; an internal lining sheet; an insulating core between the external sheet and the internal lining sheet; and indicating means to indicate correct jointing of adjacent panels, on assembly.

In one embodiment of the invention at least one of the sheets has profiled joint forming portions and the indicating means is provided on at least one joint forming portion.

The indicating means is preferably exposed on correct jointing of adjacent panels.

Ideally the indicating means is occluded on correct jointing of adjacent panels.

The indicating means may comprise a mark such as a line or band on a joint forming portion of a sheet.

In one embodiment the indicating means is provided by at least two separate indicator elements which may be spaced apart across the width of a panel. Preferably the indicator elements are aligned.

In one embodiment the indicator means or indicator elements comprise a line marked on a joint forming portion of the sheet. Preferably the line is of a dark colour.

In a preferred embodiment the line is located at a position corresponding to a correct joint between adjacent panels. The line is preferably located at a position corresponding to a margin of an external gap between adjacent panels, on assembly.

In most cases the indicating means is provided on the external sheet. Ideally the external sheet has a male projecting joint-forming portion and the indicating means is provided in the male portion.

Alternatively or additionally the indicating means is provided on the internal sheet.

In another embodiment the indicating means comprises a colour coding.

The indicating means or indicating element may comprise a band. In this case there may be two bands which are differently coded, such as colour coded.

The invention also provides an insulated panel assembly including a plurality of the panels of the invention.

Brief Description of the Drawings The invention will be more clearly understood from the following description thereof, given by way of example only, with reference to the accompanying drawings, in which :- Fig. 1 is a side cross-sectional view of a panel according to the invention; Fig. 2 is a cross-sectional view of portion of two adjacent panels separated; Fig. 3 is a perspective view of a detail of the panel; Fig. 4 is a side cross sectional view of the panels jointed together with seals omitted for clarity; Fig. 5 is a side cross-sectional view of another panel according to the invention; Fig. 6 is a cross-sectional view of portion of two adjacent panels of Fig. 5 separated; and Fig. 7 is a cross-sectional view of the panels of Fig. 6 jointed together.

Detailed Description of the Drawings Referring to the drawings and initially to Figs. 1 to 4, there is illustrated an insulated panel 1 according to the invention and comprising an external sheet 2, an internal liner sheet 3 and an insulating core 4 between the external sheet 2 and internal sheet 3. The sheets 2 and 3 are typically of steel material and the core 4 is of polyurethane or

polyisocyanurate foam material which fills the space between the sheets 2,3. The panel 1 is typically used for roofing and/or cladding systems, especially in this case for cold-store applications.

The external sheet 2 and internal sheet 3 have profiled joint-forming portions for connecting adjacent panels, on assembly as illustrated.

The external sheet 2 has an external male projecting part 10 and an internal male projecting part 11 on one side for engagement, on assembly, with a corresponding external recess or female part 12 and internal recess or female part 13 respectively on the opposite side of the panel. A seal 52,53 may be placed in one or both of the recesses 12,13 for sealing engagement, on assembly, with the male projecting parts 10,11 of an adjacent panel. The seals are typically of silicone and are site-applied.

Both the external sheet 2 and the internal sheet 3 are turned back to define a male projecting part 10,11 on one side and a female recess part 12,13 on an opposite side of a panel. Each male part 10,11 comprises an outwardly extending leg 20 and an inwardly extending leg 21 which terminates in a clip portion 22 which is embedded in the insulating core 4. The corresponding recesses 12, 13 are formed by similarly shaping the ends of the external and internal sheets 2,3. The recesses 12,13 are defined by an outwardly extending leg 24 and an inwardly extending leg. Again, the sheets 2,3 terminate in clip portions 23 which are embedded in the insulating core 4.

The outwardly extending leg 20 extends at an angle A of from 15° to 25°, ideally about 19° to the horizontal. The inwardly extending leg 21 extends at an angle (3 of from 2° to 8°, ideally about 5° to the horizontal. This facilitates ease of engagement of a male projecting part in a corresponding recess whilst ensuring adequate insulation at the joint and facilitating filling of the area defined by the male projecting part with foam on manufacture of a panel.

The insulating core at the edges of the panel between the joint forming portions engage on assembly as illustrated in Fig. 3 to provide an insulated substantially air- tight joint. In this case the exposed section of the insulating core is of generally trapezoidal shape with a male part 30 defined at one edge and a female recess part 31 defined at an opposite edge. The webs of the trapezoidal sections of the insulating core extend at an angle of from 100° to 120°, ideally about 110° to the base or top of the trapezoidal section. Thus, the angle oc is about 20°. This facilitates effective jointing whilst facilitating economic manufacture of the panel.

On assembly, the exposed gap g is about 3 mm to facilitate expansion and contraction, in use.

A seal trap is also provided at the joint between the panels at least on one of the inside and outside, in this case on both the inside and outside. The seal trap is defined by a recess 40 provided in the outwardly extending leg 20 of the male projections 10,11 and an angled lead-in portion 41 of the sheets 2,3. After on-site assembly of the panels, a waterproof sealant 50 such as a gun applied silicone may be injected into the region defined by the recess 40 and lead-in portion 41 through the outer and/or inner gap. The sealant 50 becomes trapped between 40 and 41 and is firmly retained in situ, on setting. This is important in ensuring that the integrity of the seal 50 is maintained when the exposed walls of the panels are washed for cleaning, in use, even when cleaning is carried out using pressure jet washing.

Indicating means are provided to indicate correct jointing of adjacent panels, on assembly. In this case the external face of the projecting part 10 has markings which indicate whether a correct joint has been made, on assembly. Referring in particular to Fig. 3 the markings in this case comprise a line 26 which is printed, for example by ink jet printing onto the outwardly extending leg 20 of the male projecting part 10. In this case there are two line sections which are spaced apart across the width of the panel to reduce printing costs. Each line 26 is spaced outwardly from the external edge of the outer sheets for a distance corresponding to the gap g, i. e., 3 mm. On

assembly, the line 26 should be in line with the outermost edge of the external sheet of an adjacent panel at the joint. In this way assembly is assisted and the alignment of the panels can be readily checked. If the line is visible and in line with the edge, the joint is correct, if not a correct joint is not made.

In the arrangement of Figs. 5 to 7 the markings in this case comprise colour coding provided by a first indicating band 28 in the region bc and a second indicating band 29 in the region ab of the projecting part 10. The first band 28 may be coloured red and the second band 29 may be coloured green. When adjacent panels are correctly jointed an assembly, as illustrated in Fig. 2, the red band 28 is occluded and the green band 29 is visible. Thus, a simple visual inspection of the joint indicates whether the joint has been correctly assembled. If there is an error such as an excess gap at the joint portion of the red band 26 will be visible, on inspection.

It will be appreciated that many other types of alternative or indeed similar indicating means may be used. For example, a similar indicating means may be provided on the internal sheet in addition to or as an alternative to the external sheet. The indicating means can be of any suitable form. For example, the code may be a bar-type code.

The invention provides an insulation panel which can be readily checked to ensure that the correct jointing technique has been used on assembly. Heretofore incorrect jointing was difficult to detect without carrying out extensive and expensive tests.

The invention provides an insulated panel with side edges which are arranged for highly efficient insulation.

It will be appreciated that the panels may be provided with opposite side edges or two different panels with a similar profile on both side edges may be provided.

The invention is not limited to the embodiments hereinbefore described which may be varied in construction and detail.