Roof covering or wall covering

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 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.

The invention relates to a roof covering or wall covering for a building or 
the like. 
The steel profile-sheet (trapezoidally corrugated metal sheet) coverings 
mentioned here with insulating materials possibly arranged thereon find 
frequent use. At the same time, it has emerged that, in the event of fire, 
the heat is removed upwards from the trapezoidally corrugated metal sheet, 
and under these circumstances, there is a 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 
trapezoidally corrugated metal sheet. In the event of 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 known to suspend a 
fire-protection layer composed of special panels beneath the trapezoidally 
corrugated metal sheet. This solution is, however, complicated and 
consequently 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 liberate gases which 
have disadvantageous consequences in numerous respects, for example they 
make the extinguishing operations more difficult. 
In order to eliminate these disadvantages, it is known from German 
Offenlegungsschrift 3,615,116, to arrange containers or the like filled 
with water in the channels of the trapezoidally corrugated metal sheet. 
This has, however, the disadvantage that if the containers arranged in the 
channels burn through in the event of fire, water or the like escapes 
therefrom and can drain away without having any effect unless the 
supporting layer composed of individual (strip-like) trapezoidally 
corrugated metal sheets is constructed in a complicated manner so as to be 
watertight. But even in the case of watertightly constructed supporting 
layers, the water drains (laterally) out of the burnt-through point in the 
container, in particular if the covering is inclined. As a result of this, 
the water may get into regions which are situated outside the seat of the 
fire and in which it has virtually no effect. 
Starting from this point, the invention is based on the object of further 
developing a roof covering or wall covering of the type mentioned in the 
introduction so that the fire-retarding substance fulfills its planned 
effect as ideally as possible in the event of fire. 
This object is achieved by a roof covering or wall covering having the 
features of a supporting layer of corrugated metal steel, having open 
channels and a fire-retarding liquid located in the channels, and at least 
some of the fire-retarding liquid is thickened. Thickening the liquid 
arranged in the channels achieves the result that it is unable, or only 
insignificantly able, to flow away from the seat of the fire. 
Expediently, thickened water is used as fire-retarding liquid, organic 
substances or a mixture of organic and inorganic substances preferably 
being used for thickening. As a result of this, the thickened liquid can 
be simply and cheaply produced. 
According to a particularly advantageous embodiment of the roof covering or 
wall covering according to the invention, the thickened water is 
accommodated in encasing structures arranged in the channels. These 
reliably ensure that the water is only able to escape in the event of 
fire. If one or more encasing structures melts during a fire, the 
thickening assures that the water does not abruptly, and consequently 
without essentially achieving the intended effect, drain through the 
burn-through points. Expediently, the encasing structures are of gastight 
construction. Deterioration of the thickened water occurring in the course 
of time, in particular due to the thickening substance, are thereby 
reliably avoided. 
Further embodiments of the invention relate to the structural embodiment of 
the encasing structures.

The embodiment shown in FIG. 1 relates to a roof covering 10 comprising a 
plurality of layers. The roof covering 10 is composed (from the bottom 
upwards) of a supporting layer 11, a vapor barrier 12, an insulating 
material layer 13, and also three sealing sheets 14, 15 and 16. 
The supporting layer 11 is manufactured in the normal manner from steel 
sheet, namely constructed as trapezoidally corrugated metal sheet 17. The 
trapezoidally corrugated 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. 
In the case of the roof cover 10 shown in FIG. 1, there lie in each of the 
channels 18 elongated hollow bodies, namely flexible tubes 19, which 
approximately fill the cross section of the said channels. According to 
FIG. 2, the flexible tubes 19 are of shorter construction than the 
respective channel 18. Consequently, a multiplicity of flexible tubes 19 
are arranged to lie behind one another in each channel 18. The length of 
the flexible tubes 19 is so chosen that they can be handled individually 
without difficulty. From this point of view, it has proved expedient to 
provide the flexible tubes 19 with a length of roughly 1 meter. 
In the event of fire, it is important to protect the supporting layer 11 
from overheating so that it does not lose its strength. This is achieved 
by the liquid enclosed in the flexible tubes 19. The heat developed during 
a fire causes the flexible tubes 19 situated in the region of the seat of 
the fire to burst or it melts holes in the flexible tubes 19, as a result 
of which the liquid arranged therein is liberated. 
Water 21 treated in a particular manner, namely thickened, is used here as 
liquid in the flexible tubes 19. As a result of this, the water 21 
acquires a relatively high viscosity which, when one or more flexible 
tube(s) bursts or melts through, prevents the water arranged therein from 
draining in a short time and consequently virtually unused in the event of 
fire. On the contrary, the thickened water 21 virtually remains in the 
flexible tubes 19, and to be specific, in particular also in the burst or 
burnt-through flexible tubes 19, in which it evaporates. The heat is 
removed from 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 19 in a 
static relationship consequently does not occur to an appreciable extent 
in the static aspect. In addition, the rising moisture creates an 
unfavorable climate for the occurrence of a fire in the roof finishing, in 
particular in the layers arranged above the supporting layer 11. 
Organic substances are preferably used to thicken the water 21. 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 quantities are used, these result in a substantial thickening 
of the water 21. In particular, the use of these substances also ensures 
that the water 21 retains its thickened state virtually unchanged even 
after many years, and to be specific, without a formation of putrefaction 
or the like. In order reliably to exclude a risk of putrifaction, a 
preservative may further be added to the water in addition to the 
thickening agent. Suitable preservatives are: methyl p-hydroxybenzoate, 
isothiazolynones, ethyl p-hyroxybenzoate (commercial name Solbrol A 
supplied by 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 
substances are suitable in a particularly advantageous manner as 
preservatives. 
If polyacrylic acid is used as starting substance for the thickening agent, 
the thickening of the water 21 occurs in 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 hydroxide solution, to the 
water 21 and the polyacrylic acid already dissolved in said water 21 does 
an abrupt thickening of the solution take place, as a result of which a 
highly viscous mixture is produced. Instead of sodium hydroxide solution, 
another hydroxide solution may also be used a neutralizing agent. 
Furthermore, it is alternatively possible to use low-molecular amines or 
ammonium hydroxide (sic) as neutralizing agents. 
The preservative, which may be the abovementioned substances, is added to 
the water 21 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 
21 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 acid (e.g. Carbopol supplied by the B. F. 
Goodrich Company) 
0.01-0.1% by weight of methyl p-hydroxybenzoate (alternatively one of the 
alternative preservative substances 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 21, it is also 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 neutralizing agent, for example a 20% sodium 
hydroxide solution, is then no longer necessary for preparing the 
thickened water 21. 
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 salicylic acid, but also 
in addition to the additives or as an alternative thereto, inorganic 
fillers. 
The flexible tubes 19 serving to receive the thickened water are produced 
from a thermoplastic laminate. Preferably it is composed of two layers, 
namely an (inner) ethylene-vinyl acetate copolymer layer and an (outer) 
polythylene layer. Both layers are joined to each other during the 
manufacture. A particularly good weldability of the flexible tube 19 is 
ensured by this construction of the laminate, in particular the inwardly 
situated arrangement of the ethylene-vinyl acetate copolymer layer, since, 
to form the fin welds 22, the (inner) ethylene-vinyl acetate copolymer 
layers which are directed towards each other and which have better welding 
properties, in particular a lower melting point, compared with the 
polyethylene of the outer layer, can be welded directed to each other. On 
the other hand, the polyethylene outer layer ensures a gas tightness of 
the flexible tubes 19 which is reliable even over a prolonged period, as a 
result of which a volatilization or decomposition of the thickened water 
21 arranged therein is reliably avoided. Preferably, the outer 
polyethylene layers of the laminate are thicker than the (inner) 
ethylene-vinyl acetate copolymer layers. 
The flexible tubes 19 are formed in that a flexible tube section open at 
opposite end faces is cut off in a suitable length from an endless, 
preferably cylindrical flexible 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 a result of which a fin weld 22 is produced at one 
side. The already thickened water 21 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 the thickened water 
is sealed, likewise by a hot-seal weld, so that a fin weld 22 is also 
produced here. On the basis of the mode of production described above, a 
flexible tube 19 according to FIGS. 3 and 4 is produced. This seals the 
thickened water contained therein hermetically in an airtight manner so 
that the latter is effectively protected against external influences even 
over a prolonged period of time, and to be specific, against an 
evaporation or decomposition. 
A three-layer laminate of an (inner) polyethylene layer, an intermediately 
situated aluminum layer and an (outer) polyester layer may also be used 
for the flexible tube 19. 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 the flexible tube 19 to form the fin welds 
22 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 layers, so that a satisfactory welding is 
possible without appreciable deterioration of the outer, higher-melting 
polymer layer. 
FIGS. 5 and 6 show an alternative to the flexible tube 19, namely an 
encasing body for the thickened water 21 formed as cushion 23. Said 
cushion 23 is formed from two elongated blanks 24 and 25 arranged as a 
double layer. These are first welded at the oppositely situated 
longitudinal edges 26, as a result of which two parallel longitudinal 
welds 27 are produced in this case. Then one of the two open end faces is 
sealed by a further weld, namely again a fin weld 28. The thickened water 
21 is then poured into the cushion 23 through the then still open second 
end face and the former is thereupon completely sealed by forming the 
second fin weld 28. 
Either a two-layer thermoplastic laminate of the materials described in 
connection with the flexible tube 19 or a three-layer laminate with an 
aluminum intermediate layer is suitable as material for the cushion 23. 
FIG. 7 shows an upright wall covering 29. In this, a (central) foam 
material layer 30 and the cushions 23 shown in FIGS. 5 and 6 are arranged 
between two supporting layers 11, namely trapezoidally corrugated metal 
sheets 17 with horizontally extending channels 18. The wall covering 29 
consequently has a sandwich-type construction. 
Alternatively, it is possible to accommodate flexible tubes 19 in the 
channels 18 of the trapezoidally corrugated metal sheets 17 instead of the 
cushions 23. 
The roof covering 10 shown in FIGS. 1 and 2 and the wall covering 29 shown 
in FIG. 7 each have flexible tubes 19 or cushions 23 arranged in one layer 
behind one another in the channels 18 of the trapezoidally corrugated 
sheets 17. In contrast to this, it is alternatively conceivable to arrange 
thinner flexible tubes 19 or cushions 23 with smaller cross-sectional 
dimensions also situated next to one another or above one another in a 
multiplicity of layers in the channels 18. 
According to a preferred further development of the invention, flexible 
tubes 19 or cushions 23 containing unthickened water and thickened water 
21 are arranged alternatingly in the channels 18. The cushions 23 or 
flexible tubes 19 containing thickened water 21 then form barriers which 
seal the channels 18 in a liquid-tight manner against a drainage of the 
unthickened water after the cushions 23 or flexible tubes 19 receiving the 
latter have burst or burnt through. It is also conceivable to arrange a 
multiplicity of cushions 23 or flexible tubes 19 containing unthickened 
water between every two cushions 23 or flexible tubes 19 containing 
thickened water 21.