CA1335532C - Roof covering - Google Patents

Abstract

A roof covering or wall covering for a building or the like comprising a supporting layer having open channels, preferably made of corrugated metal sheet.
Encasing structures, filled with a fire-retarding substance, are located in the channels of the supporting layer. The fire-retarding substance is preferably a thickened liquid. Since the liquid is thickened, it cannot escape or can escape only very slowly from leaky points in the supporting layer in the event of fire. This ensures an evaporation of the fire-retarding liquid to remove the thermoenergy produced during the fire.

Description

1 335~32 The invention relates to a roof covering for a building or the like. According to the invention, a roof covering for a building comprises a base layer having open channels, and with hollow bodies filled with a fire-retardant substance arranged in the channels, which arepreferably defined by a trapezoidally corrugated sheet.

Such trapezoidally corrugated sheets, particularly of steel, and possibly associated with insulating materials, find widespread use. At the same time, it has emerged that, in the event of fire, the heat passes upwards from the trapezoidally corrugated metal sheet, and under these circumstances, there is the risk that flammable materials above the trapezoidally corrugated metal sheet will ignite. In addition the thermal energy acting on the trapezoidally corrugated metal sheet results in the gradual reduction of the load-carrying capacity of the sheet. In the event of.....

~ 335532 fire, this results in an acute danger of collapse.

In order that the stability of the trapezoidally corrugated metal sheet remains intact in the event of fire, it is 5 known to suspend a fire-protection layer composed of special panels beneath the trapezoidally corrugated metal sheet. This solution is, however, complicated and conse-quently expensive. In addition, the heat radiation is only screened from the trapezoidally corrugated metal sheet by the fire-protection layer but not eliminated, whereupon there is formed, in the burning room, a heat build up which may bring about an intensification of the fire. Finally, the special panels of the fire-protection layer may liber-ate gases which have disadvantageous consequences in numer-15 OUS respects, for example they make the extinguishing op-erations more difficult.

Starting from this point, the invention is based on the objective to further develop a roof covering of the above 20 type in such a way that in the event of fire the heat im-pact on the supporting layer will be kept low over a period as long as possible.

This objective is achieved by a roof covering possessing 25 the features of claim 1. The fire retarding substance ful-fills two functions. On the one hand, the trapezoidally corrugated metal sheet is protected from overheating and so from a decrease in its load-carrying capacity. On the other hand, the insulating materials arranged on the steel 30 profile sheet are saved from being affected by the fire. In addition, the fire-retarding substance is filled into oblong hollow bodies which are arranged in the channels, filling out the profile of the latter completely or in parts. This way, the fire-retarding substance can be put 35 exactly in the desired place. In addition, the hollow bodies effectively prevent the fire-retarding substance from evaporising. Through the choice of material for the hollow bodies the release of the fire-retarding substance 1 3~32 which is dependent on heat-impact can be controlled.

According to an especially advantageous embodiment of the invention, each channel is equipped with separate hollow 5 bodies lying behind one another and holding the fire-retarding substance. Expediently, the separate hollow spaces of each channel are formed by equipping each channel with several hollow bodies, which are lying behind one another. With this embodiment, spaces in between the hollow o bodies which are spaced behind one another are partitioned against leakage of liquids. This embodiment has the advantage that in the case of a partial heat-up of the covering, only one or a few hollow bodies in the region of the source of fire melt and release fire-retarding 15 substance. The liquid tight partition prevents the fire-retarding substance - especially with a horizontally inclined covering - from running to a less endangered area of the covering, where the effect of this substance is not needed. Such hollow bodies can be designed as containers, 20 tubes or cushions.

According to a further especially expedient embodiment of the invention, thin tubes form the hollow bodies, with each channel being equipped with a continuous tube extending 25 over the whole length of the channel. Both tube ends are, at the oppositely situated end faces of the supporting layer in which the channels open into, connected on either side to a (shared) reservoir which holds the fire-retarding substance. The reservoir can be constructed as a container, 30 particularly a water-container, being assigned to each of the oppositely situated end faces of the supporting layer.
Alternatively, it is also possible to connect each of the opposite lying ends of '~he thin tubes in the channels with a heat-retarding (metal) conduit, preferably an existing 35 water supply system, which can be fed with the fire-retarding substance.

Expediently, thickened water is used as fire-retarding liquid, organic substances or a mixture of organic and inorganic substances preferably being used for thickening.
This way, the thickened liquid can be produced simply and s cheaply. This thickening of the fire-retarding substance guarantees that in the event of fire it can not drain without being used completely or to a substantial extent.

Preferred embodiments of the invention are described in o more detail below with reference to corresponding drawings which show:

Figure 1 in cut-away, perspective view a roof covering with a supporting layer constructed from trapezoidally corrugated metal sheet and con-tainers being arranged in the channels of the trapezoidal profile as well as further layers lying thereupon.

Figure 2 an enlarged cross-sectional view of part of the roof covering with hollow bodies arranged in the trapezoidal profiles according to Figure 1, Figure 3 a cut-away perspective view of part of the roof covering according to Figure 2 with a hollow body being round in profile namely a tube, Figure 4 a cross-sectional view of a special tube embodi-ment with a filler socket arranged in a channel of the trapezoidal profile, Figure 5 a cross-sectional view of three tubes arranged in a channel of the trapezoidal profile, 5 Figure 6 a view of the supporting layer according to Figure 1 with hollow bodies of a further embodi-ment arranged in the channels, Figure 7 a cross-sectional view of a roof covering with an insulating layer sprayed on the supporting layer, s Figure 8 a perspective view corresponding to Figure 1 of a roof covering with tubes holding the fire-retarding substance, Figure 9 a view corresponding to Figure 2 of tubes o arranged in a channel of the trapezoidally corrugated metal sheet, Figure 10 a side view of the filled tube, Figure 11 a plan view onto the tube of Figure 10, Figure 12 a side view of a filled cushion as an alter-native to the tube, Figure 13 a plan view onto the cushion according to Figure 12, Figure 14 a plan view onto the supportive layer with a further embodiment of the hollow bodies, that is to say tubes, arranged in the channels, which are connected to two oppositely situated water containers, sitting at the end faces of the supporting layer, Figure 15 a view according to Figure 14 of a further embodiment of the invention, with the thin tubes being connected to conduits sitting at the end faces of the supporting layer.

The embodiment shown in Figure 1 relates to a roof covering 10 comprising a plurality of layers. The roof covering 10 is composed (from the bottGm upwards) of a supporting layer 11, a vapor barrier 12, an insulating material layer 13, 1 33~532 and also three sealing sheets 14, 15 and 16.

The supporting layer 11 i s manufactured in the normal manner from steel sheet, namely constructed as trapez-5 O i dally corrugated metal sheet 17. The trapezoidally corru-gated metal sheet 17 consequently has channels 18 which are arranged next to one another and which are open upwards, i.e. towards the vapor barrier 12. With an inclined arrangement of the roof covering 10, the channels 18 are oriented in the parallel extension direction to the roof ridge, that is to say, extend roughly horizontally.

A lower cross-plate 24 of each channel 18 is equipped with spaced holes 21.

In the case of the roof cover 10 shown in Figure 1, there lie in each of the channels 18 elongated hollow bodies, namely containers 19. According to Figure 2 the outer contours of container 19 are adjusted to `fit the inner 20 dimension of channels 18, that is to say they have a trapezoidal profile. The vapor barrier 12 rests on the upper cross-plates 20 of the supporting layer 11.

In the event of fire, it is important to protect the 25 supporting layer 11 from overheating so that it does not lose its strength. This is achieved by the heat-retarding substance 49 enclosed in the containers 19. The heat developed during a fire causes the walls 22 of containers 19 to melt, as a result of which the fire-retarding 30 substance 49 in containers 19 is released. The heat is carried off supporting layer 11 due to the high heat capacity of fire- retarding substance 49 and to the necessary evaporation energy. Besides, the rising moisture creates a climates unfavourable for the formation of a fire 35 in the roof layer. Finally, the heat-retarding substance 49 can drip out of channels 18 down throuyh holes 21 in the lower cross-plates 24.

1 3~5~2 Figure 3 shows a hollow body constructed as a tube 29 laid down in channel 18. The profile of tube 29 results from placing it in the trapeze profile 17. The wall 22 of tubes 29 ist flexible.

According to Fig. 4, tube 29 is equipped with a filler socket 23 for filling in fire-retarding substance 49. This filler socket 23 makes it very easy to fill fire-retarding substance 49 into the tube 29 after putting on roof covering 10. Apart from that, fire-retarding substance 49 can be changed or topped up at any time. Filler socket 23 is firmly connected to wall 22 of tube 29, in particular welded. Supporting layer 11 has an opening 25 to fit filler socket 23 in the region of the lower cross-plate 24.
15 Opening 25 is drawn in Figure 4 with broken lines. In order to fix the filler socket 23 in the opening 25, the former is equipped with an outer thread 26 and a fitting nut 27.
Nut 27 guarantees that filler socket 23 can not be pulled out the lower cross-plate 24. Containers 1g can also be 20 equipped with a filler socket in a corresponding way.

Figure 5 shows an embodiment with several, namely three pipes 28 lying in channel 18 of supporting layer 11. This has the advantage that tubes 28 are smaller and therefore 25 easier to handle and it is possible that always the same tubes 18 can be used for different size trapeze profiles 17.

In the embodiment of the invention according to Figure 6, 30 each channel 18 of supporting layer 11 holds several hollow bodies, namely short containers 30, lying behind one another. Containers 30 lie in each channel 18 spaced out in small distances one behind the other, thus leav;ng an empty space between neighbouring containers, which is filled with 35 an appropriate insulating partition 31. Insulating partition 31 can be made of sprayed foam (PU-foam), so that it is virtually water-tight. That way, a number of separate chambers ;s formed, in each case lying between two insulating partitions 31 in channels 18. In the event of a local fire, these chambers guarantee a well-aimed, efficient protection, as fire-retarding substance 49 can not drain to areas next to the source of the fire, where it 5 would be virtually ineffective.

Figure 7 shows containers 32, which do not fill the profile of channels 18. Compared to channel 18 they are smaller in height. Due to the reduced profile, containers 32 hold a smaller volume of fire-retarding substance 49, so that the dead-weight of roof covering 10 is reduced. What is more, this embodiment leaves space above containers 32 for wires (not shown) or the like, which have to be installed on the roof covering 10.

Furthermore, Figure 7 shows an insulating layer which is simplified compared to the one in Figure 1. The former layer consists of a homogenous foam material layer 34, which can simply be sprayed on supporting layer 11 and 20 containers 32 lying in channels 18. At the same time, foam material layer 34 can be used for forming insulating partition 31 between containers 30. The foam material layer 34 is preferably made of a multi-compound-PU-foam synthetic material.

The roof covering 10 shown in Figure 8 has elongated hollow bodies lying in channels 18, which almost fill out the channel profile. These hollow bodies are constructed as tubes 35, which are according to Figure 9 again shorter 30 than each corresponding channel 18. That means, there are several tubes 35 lying behind one another in each channel 18. The chosen length of tubes 35 guarantees that every single tube is easy to handle. Preferably tubes 35 are one meter in length.

The tubes 35 serving to receive the heat-retarding substance 49 are made of a thermoplastic synthetic laminate. Preferably it is composed of two layers, namely 9 1 3~532 an (inner) ethylene-vinyl acetate copolymer layer and an (outer) polyethylene layer. Both layers are joined to each other during the manufacture. A particularly good weldability of the tube 35 is ensured by this construction 5 of the laminate, in particular the inwardly situated arrangement of the ethylene-vinyl acetate copolymer layer, since, to form the fin welds 36, the (inner) ethylene-vinyl acetate copolymer layers which are directed towards each other and which have better welding properties, in o particular a low melting point, compared with the polyethylene of the outer layer, can be welded directly to each other. On the other hand, the polyethylene outer layer ensures a gas tightness of tubes 35 which is reliable even over a prolonged period, as a result of which a 15 VO latilization or decomposition of the fire-retarding substance arranged therin is reliably avoided. Preferably, the outer polyethylene layers of the laminate are thicker than the (inner) ethylene-vinyl acetate copolymer layers.

20 The tubes 35 are formed in that a tube section open at opposite end faces is cut off in a suitable length from an endless, preferably cylindrical tube extrudate, having a wall thickness of around 0.4 mm, and first closed by welding at one end face, preferably by a hot-seal weld, as 25 a result of which a fin weld 36 is produced at one side.
The fire-retarding substance 49 is then poured in through the then still open end face of the flexible tube prepared to this extent. Thereafter, the second end face left open to pour in fire-retarding substance 49 is sealed, likewise 30 by a hot-seal weld, so that a fin weld 36 is also produced here. On the basis of the mode of production described above, a tube 35 according to Figures 3 and 4 is produced.

A three-layer laminate of an (inner) polyethylene layer, an 35 intermediately situated aluminum layer and an (outer) polyester layer may also be used for the tube 35. In this case, the aluminum layer may be formed by single-sided inner vapor-coating either of the polyethylene or the polyester layer. The welding of tube 35 to form the fin welds 36 is carried out here at the (inner) polyethylene layers which are directed towards each other and which have a lower melting point compared with the (outer) polyester 5 layers, so that a satisfactory welding is possible without appreciable deteriation of the outer, higher-melting polyester layer.

Figures 12 and 13 show an alternative to tube 35, namely an encasing body formed as cushion 37. Said cushion 37 is formed from two elongated blanks 38 and 39 arranged as a double layer. These blanks 38, 39 are first welded at the oppositely situated longitudinal edges 40, as a result of which two parallel longitudinal welds 41 are produced in 15 this case. Then one of the two open end faces is sealed by a further weld, namely again a fin weld 42. The fire-retarding substance 49 is then poured into the cushion 37 through the then still open second end face and the former is thereupon completely sealed by forming the second fin zo weld 42.

Figure 14 shows an embodiment with the hollow bodies formed by relatively thin tubes 43, with one continuous tube 43 lying in one channel 18. As tubes 43 can only hold a 25 relatively small volume of fire-retarding substance 49, the opposite tube ends are connected to liquids-reservoires. In this embodiment the two oppositely situated end faces 44 of supporting layer 11, i n which channels 18 open into, have each been equipped with a liquids-reservoir in the form of 30 storage container 46. All tubes 43, which are projecting from supporting layer 11 on one end face 44 open ;nto each storage container 46. This embodiment has two advantages:
On the one hand, the relatively thin tubes 43 containing the small amount of liquid only put a small weight on the 35 roof covering 10. On the other hand, a sufficient quantity of liquid is available in the event of fire, which is guaranteed by appropriate dimenions of storage containers 46. Alternatively to embodiment shown in Figure 14, it is also possible to equip only one end face 44 of supporting layer 11 with a storage container 46. In this case, the free ends of the thin tubes 43 will be sealed.

s Finally, Figure 15 shows an embodiment of the invention which also has a thin tube 43 lying in each channel 18.
Tubes 43 are fed in a different way though, namely by highly heat-retarding (metal) conduits 47. In Figure 15 each end face 44 is again equipped with a conduit 47, which has connections 48 for the ends of tubes 43. Conduits 47 are fed by a central liquids-reservoir. Here it might also be sufficiant to equip only one end face 44 with a conduit 47.

15 Expediently, conduit 47 or conduits 47, as the case might be, are installed near the edge of the roof, so that possible leakages will not affect the roof and connections 48 are easy to control.

20 Water treated in an special way, that is thickend, is preferably used as fire-retarding substance 49. As a result of this, the water acquires a relatively high viscosity which, when one or more containers 19, 32, cushion 37 or tubes 35 burst or melt through, prevents the water arranged 25 therein draining in a short time and consequently virtually unused in the event of fire. On the contrary, the thickened water virtually remains in the hollow bodies, and to be specific, in particular also in the burst or burnt-through containers 19, 32, tubes 28, 29, 35 or the like, in which 30 it evaporates. The heat is taken off the supporting layer 11 by the large heat capacity of the water (and to be specific, also in the gelled condition) and also by the energy of evaporation required. Impairment of the supporting layer 11 in a static relationship consequently 35 does not occur to an appreciable extent in the static aspect.

Organic substances are preferably used to thicken the water. As such cellulose ether or salts of an acrylic acid polymer or copolymer are, in particular, suitable. Even at the lowest concentration, that is to say, when small s quantities are used, these result in a substantial thickening of the water. In particular, the use of these substances also ensures that the water retains its thickened state virtually unchanged even after many years, and to be specific, without a formation of putrefaction or the like. In order to definitely exclude a risk of putri-faction, a preservative may further be added to the water in addition to the thickening agent. Suitable preservatives are: methyl p-hydroxybenzoate, isothiazolynones, ethyl p-hydroxybenzoate (commercial name Solbrol A supplied by 15 Bayer AG), methyl p-hydroxybenzoate (commercial name Solbrol M supplied by Bayer AG), propyl p-hydroxybenzoate (commercial name Solbrol P supplied by Bayer AG), benzoic acid, sodium benzoate, sorbic acid or potassium sorbate.
Because of their toxicological harmlessness, these 20 substances are suitable in a particularly advantageous manner as preservatives.

If polyacralic acid is used as starting substance for the thickening agent, the thickening of the water occurs in Z5 that the latter is first mixed with 0.05 to 1 % by weight, in particular 0.25 % by weight, of acrylic acid without an appreciable thickening of the water already occurring under these circumstances. Only after adding an equivalent quantity of a neutralizing agent, for example a 10 % sodium 30 hydroxide solution, to the water and the polyacrylic acid already dissolved therein does an abrupt thickening of the solution take place, as a result of which a highly viscous mixture is procuces. Instead of sodium hydroxide solution, another hydroxide solution may also be used as neutralizing 35 agent. Furthermore, it is alternatively possible to use low-molecular amines or ammonium hydroxides as neutralizing agent.

~ 335532 The preservative, which may be the abovementioned substances, is added to the water before the neutralization of the polyacrylic acid, that is to say, some time before the occurrence of the thickening.

The example below is intended to clarify the relationship between the water and the thickening agent and also the preservative in using polyacrylic acid as starting substance. Accordingly, the following mixing ratio is used:

94.9 - 99.74 % by weight of water 0.05 - 1 % by weight of polyacrylic~ci~e k~
(e.g. Carbopol supplied -y the B.F.Goodrich company) 0.01 - 0. 1 % by weight of methyl p-hydroxybenzoate (alternatively one of the alternative preservative sub-stances specified above within the specified quantity range) 0.2 - 4 % by weight of a 10 % solution of sodium hydroxide In order to avoid the neutralization of the thickening agent in preparing the thickened water, it is also 25 conceivable to add the sodium salt of a copolymer (Hostacerin supplied by Hoechst company) directly to the water to be thickened. The use of a neutra~nizing agent, for example a 10 % sodium hydroxide solution, is then no longer necessary for preparing the thickened water.

The thickening of the water with the aid of cellulose ether can be carried out with 1 - 5 % by weight, in particular 3 % by weight of methylcellulose. The following mixing ratio then results:

94.9 - 98.98 % by weight of water 1 - 5 % by weight of methylcellulose 0.02 - 0.1 % by weight of methyl p-hydroxybenzoate (alternatively, one of the preservatives mentioned above can be used in the same weight range).

The two abovementioned mixtures may alternatively further contain additives, namely texotopic agents, for example salicic acid, but also in addition to the additives or as an alternative thereto, inorganic fillers.

Alternatively, unthickened water can be arranged in the hollow bodies. This is particularly suitable for the (thin) tubes 43 which can be filled by storage container 46 or conduits 47.

Claims (32)

1. Roof covering for a building, comprising a base layer having open channels, and with hollow bodies filled with a fire-retardant substance arranged in the channels, wherein the fire retardant substance is a thickened liquid.

2. Roof covering according to claim 1, wherein the open channels are defined by a trapezoidally corrugated sheet.

3. Roof covering according to claim 1 or 2, wherein in an inclined or horizontal roof, the channels are open upwardly.

4. Roof covering according to claim 1, wherein the hollow bodies are formed of gas-impermeable material.

5. Roof covering according to claim 4, wherein the gas-impermeable material is a thermoplastic material.

6. Roof covering according to claim 4, wherein the gas-impermeable material is polyethylene.

7. Roof covering according to claim 1, 2, 5 or 6, wherein plural separate hollow bodies are located in each channel, and insulating partitions of foamed material are disposed between the bodies or groups of adjacent bodies.

8. Roof covering according to claim 1, wherein the hollow bodies have closable filler spigots securely connected thereto.

9. Roof covering according to claim 8, wherein the base layer has openings for the filler spigots.

10. Roof covering according to claim 1, 2, 4, 5, 6, 8, or 9, wherein plural separate hollow bodies are located in each channel.

11. Roof covering according to claim 1, wherein the heat-retardant substance is water thickened with an organic substance.

12. Roof covering according to claim 11, wherein the organic substance is a cellulose ether.

13. Roof covering according to claim 11, wherein the organic substance is 1% to 5% by weight of methyl cellulose.

14. Roof covering according to claim 11, wherein the organic substance is 3% by weight of methyl cellulose.

15. Roof covering according to claim 11, wherein the organic substance is a neutralized acrylic acid polymer or copolymer.

16. Roof covering according to claim 11, wherein the organic substance is 0.05 to 1% by weight of polyacrylic acid.

17. Roof covering according to claim 11, wherein the organic substance is 0.25% by weight of polyacrylic acid.

18. Roof covering according to claim 11, 12, 13, 14, 15, 16 or 17, wherein a preservative is added to the thickening agent.

19. Roof covering according to claim 11, 12, 13, 14, 15, 16 or 17, wherein a preservative selected from an isothiazolynone, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, benzoic acid, sodium benzoate, sorbic acid and potassium sorbate, is added to the thickening agent.

20. Roof covering according to claim 1, 2, 4, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16 or 17, wherein the hollow bodies have rigid walls fitting the channels.

21. Roof covering according to claim 1, wherein the hollow bodies are tubular or cushion shaped.

22. Roof covering according to claim 21, wherein the walls of the hollow bodies are formed of a plastic laminate.

23. Roof covering according to claim 22, wherein the laminate is polyethylene modified with ethylene-vinyl acetate copolymer.

24. Roof covering according to claim 22, wherein the laminate is a three layer polyethylene/aluminum/polystyrene laminate.

25. Roof covering according to claim 21, wherein the hollow bodies are tubular and closed by fin welds at opposite ends.

26. Roof covering according to claim 21, wherein the hollow bodies are cushion-shaped and formed from opposed blanks welded around their peripheries.

27. Roof covering according to claim 1, wherein each channel contains at least one hollow body in form of a narrow continuous tube having a cross-section which is small compared with that of the channel, and opposite ends of the tubes are connected to common reservoir means containing a liquid fire-retardant substance.

28. A roof covering according to claim 27, wherein the reservoir means comprises at least one storage container to which the tubes are connected at one end face of the base layer.

29. A roof covering according to claim 27, wherein the reservoir means comprises at least one conduit of heat-resistant material transverse to an end face of the base layer.

30. A roof covering according to claim 29, wherein the conduit is of metal and connected to a central water supply system.

31. A roof covering according to claim 1, 2, 4, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16, 17, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, wherein a layer of foamed material is sprayed on the base layer so as completely to cover the channels and the hollow bodies.

32. A roof covering according to claim 1, 2, 4, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16, 17, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, wherein a layer of two component polyurethane foam is sprayed on the base layer so as completely to cover the channels and the hollow bodies.