GB2395205A

GB2395205A - Roof system providing venting during fire

Info

Publication number: GB2395205A
Application number: GB0225942A
Authority: GB
Inventors: Peter Taylor
Original assignee: RIGIDAL IND Ltd
Current assignee: RIGIDAL IND Ltd
Priority date: 2002-11-07
Filing date: 2002-11-07
Publication date: 2004-05-19
Anticipated expiration: 2022-11-07
Also published as: GB2395205B; GB0225942D0

Abstract

A roofing system 1 for venting a fire from within a building comprises at least one first roofing panel 3 and at least one second roofing panel 5. The first and second roofing panels each comprise a first sheet-like layer 9, 25, a second sheet-like layer 11, 27, and spacer means 13 separating the first and second sheet-like layers; insulation 15, 29 may be present. The roofing panel 3 comprises first and second sheet-like layers of a material, e.g. aluminium having a lower resistance to temperature than the material e.g. steel of at least one of the layers of the roofing panel 5, so as to provide venting in the event of a fire when the aluminium panel melts.

Description

ROOFING SYSTEM

This invention relates to a roofing system for venting fires. Where buildings are provided with metal clad roofing, the general arrangement is such that the roofing is made up of a plurality of joined roofing members each of which comprises a liner layer, for example, a profiled metal 10 sheet, which is attached to the roof via purling, an upper weathering layer, for example, a profiled metal sheet, a bracket system which separates the liner layer and the weathering layer, and an insulation layer provided in the gap between the liner layer and the weathering layer.

Usually aluminium is used for both the upper weathering layer and the liner layer as aluminium is corrosion resistant, for example providing corrosion protection for nominally 40 years.

In the event of a fire within a building clad with aluminium lined roofing members, the aluminium roofing sheets will melt at the relatively low temperature of nominally 660 degrees Celsius. As the heat generated in the 25 roof will be transmitted throughout the aluminium lined roofing members a relatively large area of roofing above a

- 2 - fire will readily melt and form a vent in the roof through which the smoke, flames and heat of the fire can escape from within the building. In effect, the vent in the roof caused by the melting of the aluminium sheets creates a 5 chimney for drawing out the fire and acts as an indication of the position of the fire within the building.

Aluminium is relatively expensive compared to steel.

Therefore, to reduce construction or repair costs, roofs 10 may be clad with roofing members both comprising lining and weathering layers made from galvanised steel. As galvanised steel is not as corrosion resistant as aluminium, to maintain corrosion protection some roofs may be constructed with a steel liner to reduce costs, but use an aluminium 15 weathering layer for durability.

However, in the event of a fire within a building comprising steel-lined roofing members, the temperature needed to melt the steel liner is in excess of 1000 degrees 20 Celsius, for example nominally 1500 degrees Celsius. The higher melting point of the steel liner layer results in any fire within the building being contained for a longer period until the temperature generated in the steel liner layer is sufficient for the roof to be breached to form a 25 vent. The higher resistance of the steel to temperature

- 3 means a fire can become more established within the building, leading to increased damage.

The failure, in some cases, of the steel-lined roof to 5 rupture means that there is no indication of an approximate position of the fire to fire fighting personnel outside the building There is a need, therefore, for a roofing system which 10 enables a building to be roofed relatively inexpensively but which enables fire within the building to be vented through the roof to reduce the damage caused and to give an indication of the position of a fire.

15 It is therefore an object of the present invention to provide a roofing system which overcomes or minimises these problems. According to the present invention there is provided a 20 roofing system for venting a fire from within a building comprising at least one first roofing member and at least one second roofing member, the at least one first roofing member and at least one second roofing member each comprising a first sheet-like layer, a second sheet-like 25 layer, and spacer means separating the first and second sheet-like layers, wherein the at least one first roofing

member comprises first and second sheet-like layers of a material having a lower resistance to temperature than the material of at least one of the layers of the at least one second roofing member, so as to provide venting of the fire 5 from within the building in the event of a fire.

The at least one first and at least one second roofing members may also comprise thermal insulation material between the first and second sheetlike layers. The thermal 10 insulation material in the at least one first roofing member may be of a different form and/or type from the insulation in the at least one second roofing member. For example, the at least one first roofing member may comprise loose filled thermal insulation material.

The at least one first roofing member may also comprise retaining means to prevent the insulation material from becoming displaced from between the first and second sheet like layers.

The retaining means may be a mesh, preferably a galvanised steel wire mesh.

The mesh may have a pitch of 100 mm pitch.

The wire of the mesh may have a diameter of 5 mm.

The first and second sheet-like layers of the at least one first roofing member may comprise a metal with a relatively low melting point, preferably aluminium.

5 The first sheet-like layer and the second sheet-like layer of the at least one second roofing member may comprise a metal with a relatively high melting point, preferably steel. 10 The roofing system may comprise a plurality of first and second roofing members, wherein the roofing system comprises greater than O per cent but less than 100 per cent of first roofing members, for example between 5 and 40 per cent of first roofing members, and preferably around 15 20 per cent of first roofing members.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the 20 accompanying drawings in which: Figure 1 is a plan view of a section of a roofing system according to the present invention;

- 6 Figure 2 is a cross-sectional view of the section of roofing system shown in Figure 1 taken along the line A-A of Figure 1; and 5 Figure 3 is a cross-sectional view of the section of roofing system shown in Figure 1 taken along the line B-B of Figure 1.

Referring to Figures 1 to 3, a roofing system 1 according 10 to the present invention comprises a plurality of coplanar roofing members comprising first roofing members 3, for example 1000 mm wide, and second roofing members 5, for example 1000 mm wide, arranged substantially sideby-side with the adjacent edges of the first and second roofing 15 members being overlapped, for example by 100 mm, at an endlap 7, in a manner known to a person skilled in the art to produce a substantially continuous roof surface.

The roofing members are arranged, for example, such that 20 the roofing system 1 comprises sections where a first roofing member 3 is adjacent to eight second roofing members 5 as shown in Figure 1. It should be appreciated that other arrangements of first and second roofing members are possible.

The roofing system comprises greater than O per cent but less than 100 per cent of first roofing members, for example between 5 and 40 per cent of first roofing members, and preferably around 20 per cent of first roofing members.

As shown in Figures 2 and 3, the first roofing members 3 comprise a first sheet-like layer 9 in the form of a profiled liner layer, for example 0.7 mm thick, of a relatively low melting point metal, for example aluminium, 10 and a second sheet-like layer 11 in the form of a profiled weathering layer, also of a relatively low melting point metal, for example aluminium.

The liner layer and weathering layer are profiled such that 15 the layers, when viewed in use, comprise a repeating pattern of longitudinal inverted "U" shaped ridges positioned across the full width of the layers. The bases of adjacent ridges are connected by substantially laminar regions of the layers 9, 11. Figure 1 shows a cross-section 20 of the roofing members 3, 5 substantially at right angles to the longitudinal direction of the ridged profile, whereas Figure 2 shows a cross-section of the roofing members 3, 5 substantially in the longitudinal direction of the ridged profile.

8 - The liner layer 9 and weathering layer 11 are separated by means of a spacer system 13, for example, by means of galvanised steel bars and brackets, to produce a roofing member of the required thickness.

Provided between the liner layer 9 and the weathering layer 11 is a loosely filled layer of thermal insulation material 15, for example, in the form of non-combustible material split up into small sections of thermal insulation material 10 closely butted together.

Provided between the liner layer 9 and the insulation layer 15 is a layer of galvanised steel wire mesh 17, for example of 100 mm pitch by 5 mm diameter.

The first roofing members 3 are attached to the building via steel roof purlins 19, by means of attachment means, for example stainless steel screws, attaching the lining layers 9 to the purlins 19. Isolation tape 21, for example 20 PVC tape, is applied to the roof purlins to separate the dissimilar metals of the purlin and the liner sheet.

The galvanised steel wire mesh layer 17 between the insulation 15 and the aluminium liner layer 9 of each first 25 roofing member is held in place by galvanised steel clips 23 fixed directly to the roof purling.

- 9 - The spacer system 13 of each first roofing member, separating the liner and weathering layers, is fixed to the roof purlins and the weathering layer by means of, for example, stainless steel screws.

The second roofing members 5 comprise a first sheet-like layer 25 in the form of a profiled liner layer of a relatively inexpensive metal, for example galvanised steel (or steel provided with an alternative corrosionresistant 10 coating), and a second sheet-like layer 27 also of a relatively inexpensive material, for example galvanised or like steel, in the form of a profiled weathering layer. As described hereinabove for the first roofing members, the liner layer and weathering layer of the second roofing 15 members are profiled such that the layers, when viewed in use, comprise a repeating pattern of longitudinal inverted "U" shaped ridges positioned across the full width of the layers. The bases of the ridges are connected by substantially laminar regions.

The liner layer 25 and weathering layer 27 are separated, for example by means of galvanised steel bars and brackets 13, secured in place with stainless steel screws, to produce a roofing member of the required thickness.

25 Provided between the liner layer 25 and the weathering

- 10 layer 27 is a layer of thermal insulation material 29 of a type known to a person skilled in the art.

The second roofing members 5 and the spacer system 13 5 contained within the second roofing members are attached to the building via the roof purlins 19.

Each of the exposed sides of the first and second roofing members, and regions of the roofing system where roofing 10 members are overlapped 7, may have sealing means 31, for example, continuous runs of butyl mastic tape, to prevent vapour ingress into the roofing members. Vapour ingress into the first and second roofing members may also be prevented by a vapour control layer (not shown), for 15 example, of fire retarding material, being provided in the first and second roofing members in a manner known to a person skilled in the art.

As the galvanized steel liner layers 25 and the galvanised 20 steel weathering layers 27 are relatively inexpensive compared with the aluminium layers 9, 11, the roofing system, when assembled in place on a building, will predominantly consist of second roofing members, with a relatively small proportion of the roofing system 25 comprising the first roofing members.

- 11 The aluminium liner layers of the first roofing members and/or the steel liner layers of the second roofing members can be coloured such that they have the same colour.

5 Although the second roofing members described hereinbefore comprise galvanized steel weathering layers, it should be appreciated that the weathering layers of the second roofing members may comprise aluminium to provide superior corrosion resistance.

In the event of a fire within a building comprising a roofing system in accordance with the present invention, the heat generated by the fire will cause both the steel and aluminium liner layers of the roofing system to heat 15 up. The temperature generated by the fire will depend on the fuel sources, for example, furniture, paper, plastics and/or solvents, present within the building. However, temperatures in excess of 700 degrees Celsius are common.

20 As discussed hereinbefore, the melting point of aluminium is nominally 660 degrees Celsius whereas the melting point of steel is in excess of 1000 degrees Celsius, for example nominally 1500 degrees Celsius.

25 As such, the areas of the roofing system above a fire comprising a first roofing member will readily melt and

- 12 rupture at a lower temperature than the surrounding second roofing members. Once the aluminium liner layer and weathering layer of the first roofing member are ruptured, the first roofing member forms a vent in the roofing system 5 through which the smoke, flames and heat of the fire can escape from within the building. In effect the vent in the roofing system caused by the melting of the aluminium sheets of the first roofing member creates a chimney which draws the fire from the inside of the building.

As the insulation in the first roofing members is selected to be noncombustible, the insulation when exposed to the fire by the melting of the liner layer, does not act as a fuel source for the fire in the area of the roofing system.

The venting of the fire through the thermal insulation material of the first roofing members is aided by the fact that the thermal insulation material comprises small pieces of insulation material. The small pieces of thermal 20 insulation material form a relatively poor barrier to the passage of the fire, as the fire can travel through the gaps between adjacent pieces.

When the aluminium liner layer of the first roofing member 25 is melted and ruptured by fire, the thermal insulation material is prevented from falling away from the roofing

- 13 system by means of the wire mesh layer positioned between the layer of thermal insulation material and the aluminium liner layer. Even though the liner layer has been ruptured, the wire mesh will remain held in place by the clips fixed 5 directly to the steel roof purling.

By forming a vent for the fire, the ruptured first roofing member prevents excessive heat building up within an otherwise substantially sealed building. By releasing the 10 heat, the likelihood of sufficient temperatures to cause melting of the steel liner layer of any of the second roofing members, or any other steel components of the roof, is reduced, thus limiting the damage caused by the fire.

15 As the area of the roofing system directly above a fire will initially experience relatively higher temperatures than surrounding areas of the roofing system, the first roofing member of the roofing system nearest to the fire source will melt in preference to first roofing members 20 positioned in other regions of the roofing system. Thus the presence of the vent in the roofing system can indicate the relative position of the fire to fire fighting personnel positioned outside the building, and fire fighting procedures can be directed to the correct area of a burning 25 building without the initial need for the building to be entered.

- 14 Although Figure 2, hereinbefore, shows the liner and weathering layers of the first and second roofing members having a profile of a repeating pattern of inverted "U" shaped ridges connected by substantially laminar regions, 5 it should be appreciated that the liner and weathering layers may have alternative profiles or may even be substantially laminar.

Claims

- 15 CLAIMS

1. A roofing system for venting a fire from within a building comprising at least one first roofing member and 5 at least one second roofing member, the at least one first roofing member and at least one second roofing member each comprising a first sheet-like layer, a second sheetlike layer, and spacer means separating the first and second sheet-like layers, wherein the at least one first roofing 10 member comprises first and second sheet-like layers of a material having a lower resistance to temperature than the material of at least one of the layers of the at least one second roofing member, so as to provide venting of the fire from within the building in the event of a fire.

2. A roofing system as claimed in claim 1, wherein the at least one first and at least one second roofing members include thermal insulation material between the first and second sheet-like layers.

3. A roofing system as claimed in claim 2, wherein the thermal insulation material in the at least one first roofing member is of a different form from the thermal insulation material in the at least one second roofing 25 member.

- 16

4. A roofing system as claimed in claim 2 or 3, wherein the thermal insulation material in the at least one first roofing member is of a different type from the thermal insulation material in the at least one second roofing

5 member. 5. A roofing system as claimed in claim 2, 3 or 4, wherein the at least one first roofing member includes loose filled thermal insulation material.

6. A roofing system as claimed in any preceding claim, wherein the at least one first roofing member includes retaining means to prevent the insulation material from becoming displaced from between the first and second sheet 15 like layers.

7. A roofing system as claimed in claim 6, wherein the retaining means is a mesh.

20

8. A roofing system as claimed in claim 7, wherein the retaining means is a galvanized steel wire mesh.

9. A roofing system as claimed in claim 7 or 8, wherein the mesh has a pitch of 100 mm.

- 17

10. A roofing system as claimed in claim 8 or 9, wherein the wire of the mesh has a diameter of 5 mm.

11. A roofing system as claimed in any preceding claim, 5 wherein the first and second sheet-like layers of the at least one first roofing member comprise a metal with a relatively low melting point.

12. A roofing system as claimed in claim 11, wherein the 10 first and second sheet-like layers of the at least one first roofing member comprise aluminium.

13. A roofing system as claimed in any preceding claim, wherein the first sheet-like layer and the second sheet 15 like layer of the at least one second roofing member comprise a metal with a relatively high melting point.

14. A roofing system as claimed in claim 13, wherein the first sheet-like layer and the second sheet-like layer of 20 the at least one second roofing member comprise steel.

15. A roofing system as claimed in any preceding claim, wherein the roofing system comprises a plurality of first and second roofing members.

16. A roofing system as claimed in claim 15, wherein the roofing system comprises greater than O per cent but less than 100 per cent of first roofing members.

5

17. A roofing system as claimed in claim 16, wherein the roofing system comprises between 5 and 40 per cent of first roofing members.

18. A roofing system as claimed in claim 17, wherein the 10 roofing system comprises substantially 20 per cent of first roofing members.

19. A roofing system for venting a fire from within a building substantially as hereinbefore described with 15 reference to, and as shown in, the accompanying drawings.