GB2312903A - Two - skin insulated roof - Google Patents

Description

2312903 A ROUING SYSTEM This invention relates to a roofing system and, in

particular, but not exclusively to a roofing system made from profile sheeting.

Most roof s made from prof lle sheeting use two layers of sheeting with an insulating layer in between. Historically, a separate layer system has been utilised which consists of a lower skin of sheeting made of relatively thin material, an upper skin of sheeting made of much thicker material and an insulating layer placed between the two skins. Both skins are usually profiled or corrugated with the lower skin having a shallow prof ile and the upper skin having a deeper profile. The lower skin is designed to merely bear the weight of the insulation but the upper skin is load bearing and has to be designed with sufficient tolerance to take the weight of personnel working on the roof, snow and water. The insulation layer may itself include further layers such as an impermeable lower layer and a breathable upper layer so as to keep the insulation dry. The traditional system does have some benefits. For instance, sheeting manufactured off site has a length upper limit which is determined by the transport regulations. In the UK the maximum length of sheeting which can be carried by road without a police escort is 27 metres and with a police escort is 36 metres. Many roofs have spans of over 36 metres and therefore such spans would have to be covered by multiple pieces of sheet if the sheeting had to be manufactured off site. However, because the separate layer system comprises simple pieces of roll-formed aluminium it is possible to manufacture the upper and lower skin on site so that the transportation problems 1 are avoided and the maximum length of sheeting can be increased. A further advantage is the relatively low prices for these components. Nevertheless, the system suffers from a number of disadvantages. The system is particularly labour intensive and takes time to construct. During construction it is necessary to cover the roof with the lower skin first to enable people to work under dry conditions in the structure below. However, it is tempting for personnel working on the roof to walk on this thin lower profile which is particularly hazardous as it is not suitable for load bearing activities.

A second system has been developed which reduces labour and avoids the hazards associated with the previous system. The second system utilises complete composite units consisting of a roof outer skin, a bottom lining skin and an insulation layer which are fitted together and sealed into monocoque units. Unfortunately, although the units are easily fitted, they tend to be expensive to produce. Furthermore, the complexity of the unit does not facilitate on site manufacture and for the reasons previously indicated the length of the unit is therefore limited. A system and a unit have been developed which overcome these problems and provide further advantages.

According to a first aspect of the present invention there is provided a roofing system comprising a roof outer skin layer and a composite unit for the roof interior comprising a substantially rigid insulating layer and an inner lining skin layer wherein the 2 lower surface of the insulating layer and the upper surface of the lining skin layer are fixed together so as to form a layered unit.

Preferably, the outer skin is spaced from the upper surface of the insulating layer by spacers mounted on the composite unit.

According to a second aspect of the present invention there is provided a composite unit for a roof interior comprising a substantially rigid insulating layer and an inner lining skin layer wherein the lower surface of the insulating layer and the upper surface of the lining skin layer are fixed together so as to form a layered unit.

According to a third aspect of the present invention there is provided a method of constructing a roof comprising the steps of:- (a) securing a composite unit in accordance with the second aspect of the present invention to the roof support structure; and (b) securing a roof outer skin layer to at least the composite unit.

Preferably, the outer skin layer is mounted on spacers which have been secured to the composite unit.

Advantageously, at an early stage in the construction of a building, the two layered unit may be f itted to the roof to provide a 3 waterproof layer (protecting the building interior) with sufficient load bearing capabilities to allow a workman to work on the roof prior to and during fixing of the roof outer skin. In addition, as the roof outer skin is f itted as a separate unit from the two layered unit, it may be provided with different dimensions. In particular, the outer skin can be extruded on site and its length is thereby not restricted by transportation restrictions and regulations. Thus the invention has the threefold advantage of roof cover in the early stages of production, sufficient load bearing characteristics to allow further work on the roof both prior to and during fixing of the outer sheet and on-site manufacture of the outer sheet overcoming length limitations.

As mentioned previously, the outer skin is spaced from the upper surface of the insulating layer by spacers mounted on the two layered unit. Hitherto, this has not been possible due to the lack of significant load bearing characteristics in a fibre glass insulating layer and/or an inner skin with low tolerance.

An unforseen advantage of the invention is the possibility of placing the spacers on the two layered unit to suit the unsupported spanning capability of the roof outer sheet. In the known systems the outer sheet must be supported directly by the purlins underlying the roof lining skin as the lining skin and the fibre glass offer little, if any, support. The invention offers more flexibility so that the purlins need only be placed to support the two layered unit while the two layered unit itself provides the support to the outer roof sheet. As the unsupported spanning capabilities of the two 4 layered unit are greater than the outer sheet, fewer purlins are required than would be the case if the outer sheet required direct support from the purlins. Alternatively, the expensive possibility of providing thicker outer sheets with increased tolerances and thus needing fewer purlins is avoided.

Furthermore, marking of the lower layer to reveal the position of the underlying purlins and thus appropriate support points is not required which, in addition to convenience, avoids the possibility of an erroneous mark leading to an inadequately supported outer skin.

Preferably, the spacers are made from plastic to reduce creaking noise during roof movements and to reduce heat transfer between the roof layers.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which:- Figure 1 shows a lateral cross section of a roofing system in accordance with the present invention; Figure 2 shows assembled composite units prior to fitting of the outer skin in accordance with the present invention; Figure 3 shows a composite unit in accordance with the present invention; and Figure 4 shows a halter for spacing the outer roof skin from the composite unit.

Referring to figure 1, a composite unit 2 is shown in cross section flanked by adjacent composite units 4,6 (shown partially). The units have stepped side edges which are designed to co-engage with the stepped side edge of the adjoining piece so that the respective upper and lower surfaces of adjacent units present a continuous planar surface across the roof top. Each composite unit has a lining skin 10 forming the lower surface thereof. The lining skin also continues around the stepped sides of the composite units so as to provide further protection where adjoining units abut. Each unit co-operates with adjacent units on each flank and this is effected by having a continuous longitudinal step 12 on one flank and a continuous longitudinal overhanging step 14 on the opposite flank so that the overhanging step 14 co-operates with a step 13 of the adjacent piece on one flank and the step 12 co-operates with an overhanging step 15 of the adjacent piece on the opposite flank of the unit. The lining skin 10 defines the surface of the two steps 12,14 and at the side f lanked by the step 12 continues at right angles along the upper surface 16 of the unit before folding downwardly at right angles to be terminated in the insulating layer 18. At the overhanging step 14, the lining skin extends as far as the upper surface 16 and thereafter folds away from the unit at right angles to form an overhanging lip 20 parallel with the plane of the upper surface 16.

The composite unit is secured to the purlins (not shown) by way of a screw threaded bolt 22 which has a drill bit head 24 to enhance 6 its placement in the purlins. The bolt 22 is conveniently driven into the unit f rom the upper surface of the step 12 in order to secure the composite unit to the purlins. A complimentary recess 26 is provided in the bottom surface of the overhanging step 14 so as to accommodate the head 28 of the bolt 22 when the composite units are fitted together.

The outer roof sheet 30 has a series of spaced parallel longitudinal profile ridges 32 which correspond with equivalent ridges formed in the lower skin 10 and insulation 18. The outer skin 30 is spaced from the upper surface 16 of the insulating layer 18 by means of halters 34.

During assembly, after fixing a first composite unit by way of the screw threaded bolts 22, a second composite units is laid along its flank so that the overhanging lip 20 of the lining sheet 10 on the second unit overhangs the folded back portion 40 of the lining sheet on the secured unit. The second unit is thereafter secured on its opposite flank and the process is then repeated until the roof is entirely covered with the units. Thereafter, the halters 34 may be mounted on the lip 20 and secured to the composite unit by means of a clamping screw 36 which acts to clamp together the base 38 of the halter 34, the overhanging lip 20 and the fold back portion 40. A screw threadedly adjustable wing nut 42 is utilised to urge the three pieces together and against the head 44 of the clamping screw 36 to provide a secure connection. The head 46 of the halter 34 is utilised to assist the interlocking of adjacent pieces of the roof outer skin 30. The edges of each outer sheet 30 are shaped so as 7 to clip onto the head 46 of the halter 34 in such a manner that a first sheet clips over the head of the halter on one flank and clips over both the head and the clip of the adj acent sheet on the opposite flank so as to provide a secure connection. Each sheet has an inner clip 50 on one side thereof and an outer clip 52 on the opposite side thereof so that a number of sheets may be clipped together in this manner.

The lip 20 extends longitudinally down each composite unit as does the fold back portion 40 on the opposite flank of each unit. This arrangement allows the halters 34 to be mounted at any point along the length of the composite unit. Similarly, the clipped portions 50,52 on either flank of each outer sheet 30 extend longitudinally from one end of the sheet to the other. Due to this arrangement, the position and the number of the halters may be varied and chosen so as to provide support which reflects the tolerances of the outer sheet 30. As the tolerance of the composite unit is greater than the outer sheet due to the substantially rigid insulation layer, such positioning may be independent of the positioning of the purlins upon which the composite units are placed.

The stepped co-operation of adjacent composite units means that they are relatively secure once the threaded bolts 22 are driven into the underlying purlins. The units thus provide shelter f or the interior of the construction and, additionally, provide support for personnel working on the roof top. The independence of the outer sheet construction from the composite unit construction allows the length of the former to be independently produced so as to match the 8 appropriate roof conditions and, in particular, the span of the roof As the composite unit only provides the interior roof the span length is less important and the problems of transport associated with previous constructions are avoided. Furthermore, the composite unit is load bearing and the problems associated with personnel hazard and associated interior roof damage are thereby avoided. The unit is additionally less costly than the known composite unit due to the absence of the outer roof sheet and maintains the advantage of producing the outer roof sheet on site.

The provision of the lip 20 together with the fold back portion 40 provides a convenient f irm securement point for the mounting of the halter 34. Although it is advantageous for the lip and the fold back portion to extend longitudinally along the whole length of the composite unit so as to provide f or variable positioning of the halter it is nevertheless possible for this feature to be varied so that, for instance, it could simply provide a series of possible fixing points rather than a continuous lip or fold back portion.

The height of the shaf t of the halter may be varied in order to cause a corresponding variation in the roof space between the upper surface of the insulating layer and the lower surface of the outer sheet. Such variations made be required to meet building roof space regulations.

9

Claims (8)

1 A roof ing system comprising a roof outer skin layer and a composite unit for the roof interior comprising a substantially rigid insulating layer and an inner lining skin layer wherein the lower surface of the insulating layer and the upper surface of the lining skin layer are f ixed together so as to form a layered unit.

2 A roofing system as claimed in claim 1, wherein the outer skin is spaced from the upper surface of the insulating layer by spacers mounted on the composite unit.

3 A roofing system as claimed in claim 2, wherein the spacers are made from plastic.

4 A composite unit for a roof interior comprising a substantially rigid insulating layer and an inner lining skin layer wherein the lower surface of the insulating layer and the upper surf ace of the lining skin layer are f ixed together so as to form a layered unit.

A method of constructing a roof comprising the steps of:- (a) securing a composite unit as claimed in claim 4 to the roof support structure; and (b) securing a roof outer skin layer to at least the composite unit.

6 A method as claimed in claim 5, wherein the outer skin layer is mounted on spacers which have been secured to the composite unit.

7 A roofing system as hereinbefore described and with reference to the accompanying drawings.

8 A composite roof unit as hereinbefore described and with reference to the accompanying drawings.