Note: Descriptions are shown in the official language in which they were submitted.
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ROOF CONSTP~UCTIO.~ UBC~ILI~G AS~MELY
~ackqround of the Invention
Field of the Invention
The invention is directed to roof construction
S and suspended ceiling system and, more particularly, to
a fire rated sus~ended ceiling system.
~escriPtion of the Prior Art
This invention concerns a roof structure and
suspended ceiling system consisting of a roof with a
watertight outer layer and a layer of thermal insulation
beneath it, resting on a metal roof-su~porting surface
that has a vapor barrier, plus a suspended ceiling that
is su~pended from the rocf-supporting surface with the
ceiling tile supported by suspended rails.
There is already a known roof structure and
suspended ceiling system in which the rails that sup~ort
the ceiling tiles of the suspended ceiling are sus~ended
from a rnetal corruqated roof-supporting surface. The
roof-supportina surface has a layer of sheet gypsum on
its upper side and a layer of thermal insulation such as
mineral wool above it, and this is sealed by a watertight
outer layer. The roof-su~porting surface forl~s a vapor
barrier Canadian Patent 1,062,431. It is
also known that a layer of asphalt can be ap~lied to the
roof-supporting surface to form the vapor barrier.
It has been found that in the event of fire,
the fire resistance of this syste~ does not ~eet the 90-
~inute re~uirement, ~espite the layer of sheet gypsum on
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the roof-supporting surface that forMs a heat sink,
because the metal roof-supporting surface reaches
excessively high temperatures too ra?idly.
To prevent this ra~id heating of the metal
roof-supporting surface in the space beneath the
suspended ceiling in the event of fire, a layer of
mineral wool could be applied as ther~al insulation to
the ceiling tiles of the suspended ceilin~, but t'ne
disadvantage of this arrangement is that in unfavorable
weather conditions, the dew point in the space between
the suspended ceiling and the roof-supporting surface
could shift, so the suspended ceiling would be exposed
to moisture, and this must be avoided at all costs.
To keep the dew point outside the space, even
in very cold weather, the layer of thermal insulation on
the roof-supporting surface would have to be increased
considerably, so that increased cost due to this method
would result in a very expensive roof structure and
suspended ceiling system.
.~um~mar~y of the Invention
The invention is directed to a roof construc-
tion and subceiling assembly consisting of a water imPer-
meable outer layer and a heat insulating layer installed
below the outer layer, both of which rest on a metal deck
which is a vapor barier. Eelow the metal deck, a sub-
ceiling is suspended with ceiling boards supported by
suspended supporting runners. A heat insulating layer is
installed between the deck and the subceiling. At points
of the subceilina determined by ventilation aspects of
the ceiling boards, the overlying intermediate insulation
material and ceilin~ boards are lifted to form an air
passage bet~7een the area below the suspended ceiling and
the area between the subceiling and the deck. Ceiling
boards are also maintained at these points in a lifted
position by a Member which will melt, decompose, or
otherwise lose its consistency under the influence of
heat and that after the deco~position of said member,
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said ceiling boards together with the overlying insula-
tion layer, will fall into position substantially closing
the subceiling and form a fire barrier between the area
below the subceiling and the area above the subceiling.
3rief Description of the Drawinqs
Figure 1 shows one version of a roof structure
and suspended ceilin~ system in sectional view;
Fi~ure 2 shows a sectional view of a raised
ceiling tile; and
Figure 3 shows the arranqe~ent in ~igure 2
again in prospective.
Description of the Preferred ~mbodi~ents
The invention herein is ~ased on the task of
designing a roof structure and suspended ceiling syste~
of the type described initially in such a way that with a
relatively minor addition of expense in terms of
material, fire resistance can be achieved that
corresponds at least to the 9G-minute limit.
Startin~ with the roof structure and suspended
ceiling syster,~ of the type described initially, the
probler~ of fire resistance is solved by adding an ir.ter-
mediate layer of thermal insulation in the space between
the roof-su?~orting surface and the sus~ended ceiling in
such a way that the ceiling tiles and the intermediate
insula'cion ~aterial above it are elevated at certain
points (determined on the basis of ventilation
considerations) to for~ air passages between the spaces
above and below the sus~ended ceiling. These ceiling
tiles are ~;eld in raised position by at least one element
of a substance that melts, dissolves, or otherwise loses
its strength under the influence of heat, in such a way
that in the absence of this element, the ceilin~ tiles
and the intermediate insulation ~raterial above them will
drop into a position sealing the suspended ceiling and
intermediate layer, where they are held by ~eans of the
su~porting rails.
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The roof structure and suspended ceiling
arran~e~ent, according to this invention, has the advan-
tage that despite the intermediate layer of thermal insu-
lation material, the space between the roof-supported
surface and the suspended cei]ing is sufficiently ven-
tilate~ so that there cannot be a shift in the dew point
in this space. In the event of a fire in the space
beneath the suspended ceiling, the ele~ent supporting the
upward tilted ceiling tiles dissolves, or otherwise loses
1~ it strength very rapidly owing to the heat evolved, so
the supporting effect is lost and both the ceilin~ tiles
and inter~ediate insulation on it drop down under the
influence of gravity, so they completely cover the
ceiling area previously exposed when they were tilted
upward, i.e., completely sealing the passage of air in
the space between the roof-sup~orting surface and the
suspended ceiling, while at the same ti~e, the inter-
mediate layer of thermal insulation material for,-ns a con-
tinuous layer in this space. ~t this mo~ent, a shift in
dew point is no longer of interest. Due to the insu-
latin~ effect of tnis suspended ceiling and the inter-
~,ediate layer above it, the roof-supporting surface will
heat only gradually, so the roof structure and suspended
ceiling system has a fire resistance that lasts to 90
minutes or more, i.e., it achieves the fire resistance of
concrete systems.
A device is already known for sealing an
openin~ in a fireproof ceiling with a solid me~ber that
surrounds it in the form of a frame and at least one
fireproof sheet to cover the opening, with an element
that holds the sheet directly in the open position
inserted between the fireproof sheet and a solid ~ember
of the fireproof ceiling, such that said element consists
of a substance that !nelts, dissolves, or otherwise loses
its strength under the influence of heat (for example
polystyrene foam is suita~le-for this purpose, German
~atent 1,658,786). The surprising advantageous use of
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such a device according to this invention for solving the
dew point problem while at the same time achieving a
higher fire resistance class for a roof structure and
suspended ceiling system cannot, however, be deduced from
this state of the art.
It is advantageous for the ceiling tiles with
the intermediate insulation material above them to be
held in an up~lard inclined position on a supporting rail
and to be held in this position by at least one element
consisting of a material that melts, disssolves, or
otherwise loses its strength under the influence of heat
and is positioned on the supporting rails. The air
passage thus achieved at the predetermined locations is
great enough to ventilate the space between the roof-
supporting surface and the suspended ceiling adequately.In the event of a fire, the raised ceiling tiles drop
into the closing position when their supporting element
dissolves, completely sealing the suspended ceiling and
not preventing any flow of air into the space between the
roof-supporting surface and the suspended ceiling. At
the same time, the intermediate layer of insulation
material above the ceiling tile is tiltecl in the direc-
tion of the suspended ceiling, forming an essentially
continuous intermediate layer OL thermal insulation.
It is advantageous for the tilted ceiling tiles
to be in ~uide rails that hold the position closing the .
suspended ceiling and secure the tiles in a continuous
suspended ceiling and continuous intermediate layer in
the event of a fire. This can be accomplished by means
of guide plates, wire clips, etc. ~n ornamental grill or
a light transmitting grill that allows air to pass
throu~h can be placed at those locations where the
ceiling tiles are raised so the visual impression of this
suspended ceiling will not be impaired by the raised
ceiling tiles. When tlle supportina element melts in the
event of a fire, the ceiling tile drops down onto the
relatively thin grill, or if the grill itself dissolves
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due to heat, the ceiling tile will drop down onto the
supporting rail, so again, a continuous sus~ended ceiling
is formed, preventing the passage of air into the space
between the roof-supportin~ surface and the suspended
ceiling, and maintaining a continuous intermediate layer
of thermal insulation.
As mentioned above, the element that melts
under the influence of heat should consist of a foa~
plastic such as polystyrene foa~ that Melts at 70 C. to
1~ 80 C.
The roof structure and suspended ceiling system
shown in the figures consist of a roof-supporting surface
of sheet metal with corrugated reinforce~ents. A vapor
barrier may be provided by the roof-supporting surface
itself or it may consist of a layer of asphalt or alumi-
nu~ foil applied to the roof-supporting surface 4. Above
layer 3, there is a layer of thermal insulation 2 which
may consist of mineral wool, for exa~ple. This layer of
thermal insulation 3 is sealed on the outside by a water-
2~ tight layer 1 which may consist of f1m or roofing pa~er.
The ends o~ T-shaped sup~orting rails 8 are
suspended from the roof-supporting surface 4 with the
help of wires 5, the flanges 10 support the ceiling tiles
7 of a suspended ceiling syste~. Such a suspended
ceilin~ system is also referred to as a st.ip grid
ceiling. ~n intermediate layer 11 of thermal insulation
is ap~lied to the ends 9 of supportin~ rails 8 and this
layer may consist of mineral wool.
~t certain locations, a thin grill 15 is laid
on the flan~e 10 of adjacent sup~orting rails 8. In the
area of one supporting rail 8, one edge of a ceiling tile
13 lies on this grill 15, with the tile tilted upward and
supported by means of wedge-shaped ele~ent 14 that rests
on the ~rill 15 in the area of the adjacent supporting
rail 8. Together with the ceiling tile 13, the inter-
mediate layer 16 of insulating material above the ceiling
tile is also tilted upward, and for this reason, the
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intermediate layer 11 is cut alon~ the plane of separa-
tion 12.
O~in~ to the fact that the ceiling tiles 13 are
tilted upward, air can flow from space 21 into space 2~
and vice versa throu~h the air passage 22 and the grill
15, so that air circulation in space 21 influences space
20 in such a way that despite the intermediate layer 11
of thermal insulation, there cannot be a shift of dew
point into the interior of space 20, even under extremely
unfavorable weather conditions.
The elements 14 that are in the form of a cube
in Figures 2 and 3, and in the form of a wedge in Figure ~-
1 consist of a material such as ~olystyrene foam that
melts and dissolves very rapidly under the influence of
heat. In the event of a fire in space 21, ceilin~ tile
13 therefore drops into a horizontal position on the
grill 15 when element 14 loses its strength due to heat,
or if the grill is ~lade of the sa~e material as element
14 that dissolves under heat and the ceiling tile drops
onto the supporting flange of the adjacent sup~orting
rails 8, closin~ the air passage 22. At the sa~e time,
the intermediate layer 16 of insulation material on the
ceiling tile 13 also drops into horizontal-position,
forming a continuous interr~lediate layer 11. Air is also
prevented from passing between spaces 20 and 21. In
addition, good thermal insulation of space 20 aaainst
space 21 is also achieved, so the roof-supportin~ surface
4 can heat only very slowly, and roof structure and
suspended ceiling syste~ as a whole has a fire resistance
3~ accordin~ to the 9~-~inute limitation and even con-
siderably better.
As shown in ~igures 2 and 3, the ceiling tiles
13 with the intermediate layer 14 of insulation ~aterial
above the~l can be raised into vertical position to form
the air passage 22 and kept in this position by cubicle
elel~ents 14. When these elements 14 dissolve under the
influence of heat in the event of a fire in space 21, the
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ceilin~ tiles 13 with the intermediate layer 16 of
insulation l~aterial will drop into the pro~er closing
position in the U-shaped guides 23 at the side under the
influence of gravity.
