COMPOSITE MATERIAL

Abstract: A composite material (1) formed of a perforate metal sheet (2) and a coating of vapour permeable water resistant polymer (3). The polymer coating is in the form of polyvinyl chloride or a synthetic rubber material and may be bounded by adhesive or cured onto the perforate metal sheet. The composite material can be profiled to form a supporting structure. The perforate metal sheet is ideally perforate for 25 % of its surface area thereby allowing the composite material to have 25 % of the vapour permeability of the polymer coating whilst providing a material with structural properties of a sheet metal.

Description: "Composite Material" This invention relates to a composite material. Vapour permeable, water resistant polymers are known and their vapour permeability is an important feature when being used in the building and construction industry. The polymers have the disadvantages that they are not structurally supportive and therefore their application is limited. Hitherto, such polymers particularly PVC, have been applied to non-perforated metals. This combination is used for flashings in single ply roof covering systems where the PVC is generally in sheet or coil form and is reinforced with glass fibre or some other non-rigid weave reinforcement. The reinforced polymer on its own is often too flexible to be used as flashings which have to be bent into pre-formed shapes. Thus bonding to, or coating metal gives the necessary rigidity for forming. the non-perforated metal, however, this stops the vapour permeability of the polymer which is its most unique aspect. Metal sheeting can be shaped and formed into water resistant roofing material and cladding panels. The most common application of this is profiled steel or aluminium panels which are commonly used on industrial and commercial buildings. Such roofing material is usually combined with insulation and a vapour barrier to form a roof or wall cladding system. As metal is impermeable to water vapour any moisture forming within such a roof or cladding system can have a detrimental effect on its performance by corroding the metal. There are many different roof systems of this nature available but unless they are installed 100% efficiently, problems can occur. A number of attempts have been made to resolve this problem, however these tend to be so complex that the human factor and conditions under which the work has to be carried out, are overlooked. As roofing has the highest incidence of failure of any element in a building it is of crucial importance to overcome or mitigate these problems. The substructure to a roof is also of great importance. Timber in the form of boards, plywood or particle board and non-perforated metal are the traditional surfaces to which mechanically fixed roof coverings, as distinct from bonded coverings, are fixed. However, timber has the disadvantages in this function that it can rot and it must be allowed to dry to an optimum range of value of moisture content per volume of wood as required by trade standards prior to covering. Metal or timber with a dense surface can hold any moisture that accumulates in the form of condensation or a small leak, in liquid between it and the roof covering. This can cause the metal to corrode. If the outer roof covering is metal, for example, zinc, lead or aluminium, this may also corrode. It is an object of the present invention to mitigate these problems encountered with such materials. According to a first aspect of the present invention, there is provided a composite material formed of a perforate metal sheet and a coating of vapour permeable water resistant polymer. The polymer coating may be vulcanised onto the perforate metal sheet. Alternatively, the polymer coating may be affixed to the perforate metal sheeting by means of an adhesive material. Preferably, the polymer coating is on at least one side of the perforate metal sheet. Preferably, the perforate metal sheet is perforate for 25% of its surface area. Preferably, the polymer coating is polyvinyl chloride or a synthetic rubber material. The polymer coating may be reinforced by a woven exterior surface. Preferably, the composite material is profiled to increase the supparting properties of the composite material. The composite material may be used as a supporting deck under a roof structure. Alternatively, the composite material may be used as a roofing material or other building material. According to a second aspect of the present invention there is provided a building material comprising a water impermeable, vapour permeable first composite sheet and a vapour impermeable second sheet and insulating material disposed between the two sheets. Preferably, the composite material is formed of a perforate metal sheet and a coating of vapour permeable water resistant polymer. Preferably, a plurality of fixings extend from the composite sheet through the insulating material to the second sheet. Preferably, a plurality of fixings are-, provi.dpd attaching the second sheet to a supporting structure of a building. Preferably, the fixings are sealed to the composite sheet by application of a liquid polymer to the fixing surrounds which liquid polymer may be the same material as said polymer coating. According to a third aspect of the present invention there is provided a roofing system comprising a fluid permeable support surface, an external roofing material supported by the fluid permeable support surface, and ventilation means disposed adjacent to the fluid permeable support surface. Preferably, the fluid permeable support surface is formed of a perforate sheet material. Preferably, the perforate sheet material is metal and is coated with a vapour permeable water resistant polymer. Preferably, the polymer coating is polyvinyl chloride or a synthetic rubber material. The support surface may be profiled to increase the supporting properties of the surface. The profiles may act as ventilation ducts through which air and vapour may pass. Embodiments of the present invention will now be described by way of examples only, with reference to the accompanying drawings, in which: Fig 1 is a section of a composite material in accordance with the first aspect of the present invention; Fig 2 is a section of a roof structure including the composite material of Fig 1 and in accordance with the second aspect of the present invention; Fig 3 is an isometric view of a profiled sheet material in accordance with the third aspect of the present invention. Referring to the drawings, a composite material 1 is formed of a perforate metal sheet 2 and a sheet of vapour permeable water resistant polymer 3. The polymer 3 can be applied to the perforate metal sheet 2 as a liquid coating and then cured to turn the liquid coating into a solid sheet. Alternatively, pre- cured sheets of coils of polymer 3 can be bonded with an adhesive 4 to the perforate metal sheet 2. The perforate metal sheet 2 may be up to 50% perforate and therefore the composite material 1 will have 50% the vapour permeability of the polymer coating 3. The perforate metal 2 must be a thin sheet or coil and able to be formed by means of a brake press or profiling machinery. Suitable metals are galvanised steel and aluminium, which when profiled attain a degree of stiffness. The composite material 1 can be formed into vapour permeable flashings, gutters etc in any situation where previously non-perforate metal is normally used. Referring to Fig 2, the composite material 1 can be formed into profiled self supporting roofing 5 for a roofing structure 10 by profiling the composite material 1 to enable it to be self supporting between roof supports 6. The composite material 1 can also be used as cladding sheets. The vapour permeability of the composite material 1 reduces the risk of condensation which was previously a risk in self supporting profiled non-perforate metal. The profiling, in addition to making the composite material 1 self supporting, also increases the surface area thus increasing the area of permeability per unit area of profiled material. A self supporting roof structure 10 is formed by profiling the composite material 1 to form a rigid self spanning roof panel which when combined with a width of insulating material 7 and a liner deck 8, acts as a vapour barrier. The inner deck 8 is self spanning and can be profiled and this forms a vapour check. The insulating material 7 provides insulation for the roofing structure 10. The outer deck is formed of the composite material 1 which is fixed by fixing means 11 through the insulating material 7 to the liner deck 8. The fixings 11 can be extended to the principal purlin of the roof structure 10, or separate fixing means 12 can be provided between the liner deck 8 and the roof purlins 6. It is well known to form a roof structure as described above with the outer layer in the form of metal, however such roofing structures have a very high failure rate. The proposed permeable outer layer in the form of a composite sheet 1 allows any vapour to ultimately evaporate away. Exposed fixings 11 can be sealed by in situ application of the polymer 3 in liquid form. Roof structures 10 as described above are very simple to construct, complicated profiles are not necessary and the polymer coating 3 can be coloured for aesthetic purposes. The vapour barrier in the form of the liner deck 8, whilst still important is less critical in terms of 100% effectiveness. The roof-structure 10 provides ease of removing and replacing panels. In more complex arrangements it is difficult to maintain the integrity of an area if a panel has to be removed and later replaced. Subsequent polymer coatings 3 can extend the life of the composite material 1 without prejudicing the vapour permeability and this can be carried out in situ if required. The metal sheet 2 of the composite material 1 enables the composite sheet 1 to be formed into rigid, self- spanning panels, suitable metals are galvanised steel, stainless steel and aluminium. The composite sheet 1 can also be used independently as an overlay for roofs which have moisture or condensation problems. Referring to Fig 3, a roof support structure 20 is illustrated in accordance with the third aspect of the present invention, in which a perforate metal sheet 22 is formed into a profiled sheet 23 having troughs 24 of approximate width 20 cms and rectangular peaks 25 of approximate width 80 cms. The profiling of the metal sheet 22 eliminates the need for spacers in the roof structure and the profiled sheet 23 is capable of greater spans between supports 26. The profiled metal sheet 23 is laid on and fixed to the supporting structure 26. The perforate metal is ideally perforated to at least 25% its surface area and is thick enough to support the fixings. 0.7mm thick galvanised sheet or 0.9mm thick aluminium are preferred materials. The fixings are by means of screw fixings 27 through the troughs 24 of the profiled sheet 23 into the supporting structure 26. A roof covering is then fixed to the perforate metal sheet 22. As the supporting profile sheet 23 is perforate, ventilation and airflow can pass along the channels of the peaks 25 and troughs 24 or orthogonally 1 through the perforations, across the peaks 25 and 2 troughs 24. *"> 4 Perforate metal is usually used for sound dampening and 5 not usually in a structural or decking capacity, 6 however, the ventilation properties are extremely 7 important and useful in a roof structure. The 8 profiling of the perforate metal provides cross 9 ventilation without the need for additional framing. 0 1 The perforations prevent any water caused by 2 condensation or leakage, being trapped between two 3 impervious surfaces which can lead to corrosion. Also 4 no timber is needed which could rot or cause delays 5 during construction whilst drying. 6 7 During construction of the roof, the use of a perforate 8 metal sheet profiled as described above has the 9 disadvantages that rain can enter the building. 0 Therefore the perforate metal sheet 23 can be coated to 1 form a composite material, by coating in a vapour 2 permeable water resistant polymer in the form of 3 polyvinyl chloride or a synthetic rubber material as 4 previously described. 5 6 Modifications and improvements can be made to the 7 present invention without departing from the scope of 8 this invention.

Claims: CLAIMS 1 A composite material formed of a perforate metal sheet and a coating of vapour permeable water resistant polymer. 2 A composite material as claimed in Claim 1, wherein the polymer coating is vulcanised onto the perforate metal sheet. 3 A composite material as claimed in Claim 1, wherein the polymer coating is affixed to the perforate metal sheet by means of an adhesive material. 4 A composite material as claimed in any one of the preceding Claims, wherein the polymer coating is on at least one side of the perforate metal sheet. 5 A composite material as claimed in any one of the preceding Claims, wherein the perforate metal sheet is perforate for 25% of its surface are. 6 A composite material as claimed in any one of the preceding Claims, wherein the polymer coating is polyvinyl chloride or a synthetic rubber material. 7 A composite material as claimed in any one of the preceding Claims, wherein the polymer coating is reinforced by a woven exterior surface. 8 A composite material as claimed in any one of the preceding Claims, wherein the composite material is profiled to increase the supportive properties of the composite material. 9 A composite material as claimed in any one of the preceding Claims, wherein the composite material is used as a supporting deck under a roof structure, as an exterior roofing material or as another building material. 10 A building material comprising a water impermeable, vapour permeable first composite sheet and a vapour impermeable second sheet and an insulating material disposed between the two sheets. 11 A building material as claimed in Claim 10 wherein the composite sheet is formed of a perforate metal sheet and a coating of vapour permeable water resistant polymer. 12 A building material as claimed in Claim 10 or 11, wherein a plurality of fixings extend from the composite sheet through the insulating material to the second sheet. 13 A building material as claimed in Claim 10, 11 or 12, wherein a plurality of fixings are provided attaching the second sheet to a supporting structure of a building. 14 A building material as claimed in Claim 12 or 13, wherein the fixings are sealed by application of a liquid polymer to the fixing surrounds. 15 A roofing system comprising a fluid permeable support surface, an external roofing material supported by the fluid permeable support surface, and ventilation means disposed adjacent to the liquid permeable support surface. 16 A roofing system as claimed in Claim 15, wherein the fluid permeable support surface is formed of a perforate sheet material. 17 A roofing system as claimed in Claim 16, wherein the perforate sheet materials metal and is coated with a vapour permeable water resistant polymer. 18 A roofing system as claimed in Claim 17, wherein the polymer coating is polyvinyl chloride or a synthetic rubber material. 19 A roofing system as claimed in any one of Claims 15 to 18, wherein the support surface is profiled to increase the supporting properties of the surface. 20 A roofing system as claimed in Claim 19 wherein the profiles of the supporting surface act as ventilation ducts through which air and vapour may pass.

Inventors: WATSON WILLIAM BLACK, WATSON, WILLIAM, BLACK
Applicants: WATSON WILLIAM BLACK, WATSON, WILLIAM, BLACK
Application year: 1993
Main classification: E04D5
IPC codes: E04D5, E04D12