Note: Descriptions are shown in the official language in which they were submitted.
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.....
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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
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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.
1 335532
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,
1 335532
-- 5
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
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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
-- 7
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
- 1 335532
-- 8 --
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
1 335532
- 10 -
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
1 335532
- 11 -
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.
1 335532
- 12 -
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
- 13 -
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
- 14 - 1335532
(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.
