Note: Descriptions are shown in the official language in which they were submitted.
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DY~MIT ~l~BEL ~KIl'IE!~GFS~LI.SCll~.FT
Troisdor~, District of Cologrle
Roo Constl-uction, Es~ecially for Flat and/or
Shallowl~ Inclined Roofs
The invention relates to a roof constrLIction,
especially for flat and/or sha1lo~ly inclined roofs with an
underst:ructure and a roofing skin, loosely laid thereon, of
elastic sealing sheets, optionally with intermediate layers
such as a thermal insulating layer, a protective layer, a
vapor barxier layer, etc., wherein the roofing skin is
flashed at the rim of the understructure.
The sealing of flat roofs is performed in accordance
with the flat-roof regulations of the"Zentral~erband des
Deutschen Dachdeckerhandwerkes" [Central ~ssociation of German
Roofers]. In accordance with DIN 1055 [German Industrial
Standard~, it is necessary in the building of flat roofs
to consider the wind load. In this connection, considerable
wind suction ~orces must be expected, particularly due to
vortex for~ation in the edge region of a flat roof. The roof
constructions are consequently designed, for the a~sorption
of the wind suction forces, either witll a partial-area or
total-area glued connection of the roofing skin or ~ith an
additionally applied weight in case of a loose laying of the
roofing skin, or with a mechanical, area-wide fixatiGn in
case o~ a loose laying of the roofing skin without weightin~.
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The wind suction forces are produced by an increased
wind velocity on the roof surface. These forces are even more
enhanced by vortex formation, for example conical vortices in
the,edge and corner zone of the roof surface. Thereby a
vacuum is produced on the roof construction.
German Patent No. 2,317,545 discloses an installation
for changing the air flow relationships on roof~s without slope
or with a slight slope; with the aid of this installation, the
; vortex formation and ~hus the,ensuing wind suction forces are
weakened in order to reduce in this way the load on flat roof
constructions. As~per~German Patent 2,317,545 baffles are~
arranged for th1s purpose in the region of the roof oorners of
the roof construction, these baffles reducing the vortex
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formation in the edge and'corner zone and thus decreasing the ,~
risk of lifting~off of~the roof conskruction and the ~load due ~ '~
to wind suction forces.'
; ' - The i'~vention i9 based on the object of providin~ a
, roof construction~with a~loosely laid roofing skin without ~ ~ ;
weighting and without fixation of the flat area, ~ut yet,being
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able to withstand the wind suction forces.
Accordin~g~to~the present 1nvention, there is provlded
a roof construction,;qspec~ially for flat and/or shallowy
' ~ inclined roofs;having~an understructure and a roofing skin -~
made of resilient sealing sheets loosely laid on sald under-
structure, said skin being secured to an edge zone of said
understructure, characterized in that it comprises: an inter- '~
space provided between said roofing skin and said understruc-
ture, and sealing means for sealing off said interspace and
preventing outside air entering into said interspace.
The type of construction of the roofing seal'accord-
ing to this invention in a loosely laid roofing skin with the
roof surface being exposed to wind load is based on preventlng
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air pressure compensation between the loosely laid roofing
skin (roofing seal) and the understructure.
Considering the roofing.seal.with loosely laid struc-
ture a multiple-layer pack with the supporting understructure,
thermal insulating layer, roofing skin, then it becomes.clear
. that atmospheric air pressure is ambient in the layers, this
pressure urging the roofing skln upwards in case of a vacuum
above the roof surface, produced, for example, by wind suction
f~rces. During this process, the interspace in the multiple-
10. layer pack is increased until here, too, the same pressure --
subatmospheric pressure -- is produced as ambient on the
outside surface of the roofing skin. As long as equal pressure
relationships prevail on the outside of the roofing skin and
on the inside in the interspace, no further movement of the
roofing skin takes place. By means of the solution according
to the invention, pressure compensation in the multiple-layer
pack and/or between the roofing ~kin and the understructure is
prevented. For this purpose, the sealing means are preferably
provided in the zone of the roof edge and the roof perforations
and a sealing action is produced by a tight understructure in .
the zone of the entire roof surface.
Therefore, according to the prior art and in accord-
ance with the flat-roof guidelines of the Central Association
of German Roofers, wind suction forces representing a lessening
of the air pressure on a surface exposed to wind load and
tending to move this surface in the direction toward the sub-
atmospheric pressure are prevented by either
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providing a roof surface ~eighting which is equal to or laraer
than the pressure difference, or by absorbing the pressure dif-
ference by way of the deformation of the roofing skin and
transmission of the occurring tensile forces into fastening
points. In contrast thereto, according to the invention, the
pressure difference is reduced by the feature that the excess
pressure underneath the roofing skin is decreased due to lack
of connection with the outside air, i.e. by preventing the
influx of air into this interspace between the roofing skin
and the understructure, until pressure equalization has been
attained.
In a further development of the inventlon, the
further provision is made to prevent the influx of air into
the interspace between the roofing skin and the understructure
by arranging a seal in the zone of joints for the joints them-
selves with the aid of sealing strips, sealing compounds, foam
materials, or similar means, or by establishing tight connec-
tions beside the joints on both sides on the understructure.
An elastic, extensible sealing sheet resistant to tensile and
tearing stresses,having an appropriate weathering resistance,is
~o be employed for the roof construction of this invention as
the so~called outer membrane. These required properties are
met, for example, by thermoplastic or elastomeric~ or
thermoplastic-elastomeric synthetic resin sealing sheets
on the basis of soft PVC, polyisobutylene, butyl rubber,
polychloroprene, chlorosulfonated polyethylene, ethylene-
propylene-terpolymer elastomer, with or wit~out fabric
reinforcement. The understructure, as the so-called
second mernbrane, however, is to be designed with a sufficicnt
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rigidity and static stability to ahsorb the wind suction
forces without resiliency. The understructure can consist,
for example, of a solid concrete ceiling, a wrefabrlcated,
concrete or lightweight concrete, sectional ceiling with
sealed joints, a roofing seal in finished form glued over its
entire surface to a substrate, for example on a bitu~inous
basis with good adhesion to the substrate, trapeæe sheet-metal
roofs, old bituminous roofs, or a roofing surface formed from
chipboards with sealed joints.
In addition to providing a tight understructure,
i.e. the surface to be sealed by the roofing skin, this latter
skin must also not only be attached to the edge of the roof, bu
must be sealed as well. For this purpose, in a further develo
ment of the invention, it is proposed to flash the roofing skin
in the zone of the rim of the understructure so that it is
sealed off by mechanical means with the use of contact pressure
by means of sealing strips, sealing compounds, etc. and/or
by means of solution welding, by means of adhesion promot~rs,
adhesive strips, or the like. The means to be utilized for
the seal also depend on the materials employed for the roofing
skin; for example, when using soft PVC sealing sheets,
solution welding can frequently be performed for bonding the
sheets to connecting materials whereas, or example, when
using sealing sheets on EPDM basis, adhesive strips and/or
corresponding adhesion promoters are utilized for sealing pur-
poses.
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~ nothcr adval-tageous eml~odiment of the invention
provides that air is removed by suction during the building
of the roofing seal in order to reduce the air pressure in
the interspace bet~een the roofing skin and the understructure.
In this way, the interspace between the roofing skin and the
unders-tructure can be initially kept maximally small, and at
the same time a planar contacting of the roofing skin, which is
loosely laid, against the roof surface can be obtained from the
beginning.
It is of no significance for the construction of the
roof of this invention without pressure compensation with a
loosely laid roofing skin and for the functioning of this in-
stallation whether further, loosely laid intermediate layers
are present between the roofing skin and the understructure.
If intermediate layers exist which are firmly joined to the
understructure, then these intermediate layers constitute, in
the function of the roof without pressure compensation, an
integrated component of the understructure and take over the
tasks of the latter~ There are no objections, either, asainst
laying, for exam~le, cover panels on the roof construction of
this invention in order to ~ake it possible to walk on the
roof surface. These do not impede the function of the roofing
structure of this invention, either.
The invention will be explained in greater detail
in the drawings showing examples, to wit: ~
Figure 1 shows a cross section of a configuration
of the edge of a flat roof,
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Figure 2 sllows a cross section of a roof gutter
installed in the ~lat roof,
Figure 3 shows a cross section of a configuration
of a 1at roof edge for a renovated bituminous roo~,
Figures 4 and S show cxoss sections of various
connections for mounting rings or dome-shaped skylights,
Figures 6 and 7 are cross sections o~ various wall
connections of the roofing seal,
E'igure 8 is a cross section of an attic connection
o the roofing seal,
Figure lO shows schematically a house with flat roof.
Figure 9 shows a schematic demonsl:ration of the
vacuum roof construction according to the invention.
Figure 9 shows the basic structure and mode of opera-
tion of the roof construction according to this invention.
The roofing skin 6 of an elastic syn~hetic-resin sealing sheet
is placed upon the mechanically rigid understructure l, which
latter is adequately dimensioned statically for absorbing wind
suction forces and is sealed against the influx of air, and
is firmly connected to the understructuxe l in the edge zone 37,
forming a seal. Between the understructure l and the roofing
skin 6, the interspace 36 is produced. The wind oncoming in
the direction of arrow 38 produces a vacuum due to wind
suction forces in the edge region due to vortex formation by
increased wind velocity on the roof surface while flowing in
the direction of arrow 39 in the zone 40 above the roofing
skin 6. However, since atmospheric air pressure is ambient
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in thc interspace 36, the roofincJ skin 6 is urged upwardly in th
direction of arrow 41 on account thereof. During this process,
the interspace 36 is increased, and the pressure therein dro~s
until it is equal to the pressure prevailing on the outer
surface of the roofing skin. ~s lony as the same pressure
is ambient on the two sides of the roofing skin 6, no further
movement of the roofing skin takes place. This means that
there will not be any further elongation of the roofing skin 6,
either, and the latter is in a load--free condition. The
vacuum in the interspace 36 now leads to the effect that the
understructure 1 is urged upwardly by the full atmospheric
pressure prevailing therebelow, but absorbs this pressure due
to its construction.
In order to provide the roof construction of this in-
vention in practice, it is thus necessary to provide sufficient
seals for the outer membrane, namely the roofing skin, the
inner membrane, namely the understructure, and for the air
space disposed therebetween, regarding the influx of air and
thus for the prevention of a pressure compensation. Figure 1
shows an example for the edge construction of a ro,f structure
with loosely laid roofing skin. The understructure 1, for ex-
ample a poured concrete ceiling, is fashioned in the roof edge
zone with the upwardly eY.tending rim la. This understructure 1
is sealed by a multiple-layer roof seal. In the illustrated
embodiment, a loosely laid protective layer, e.g. a polyester
mat, is disposed direc~ly on the understructure, followed by
the vapor barrier ilm 3, e.g. a polyethylene film, laid
loosely thereon, and thereover a thermal insulating
layer 4, for e~ample of polystyrelle foam panels,
which la~ter are intcrlockecl alon~ t:heir edges, is tl~en loosely
placed thereovex. The thermal insulating layer, however, can
also be produced from other foam materials, for example from
phenolic resin foam materials, polyurethane fo~m materials,
polyethylene foam materials, crosslinked polyethylene foam
materials. The protective layer 5, for example a glass mat
having a weight per unit area o above 100 g/m2, is loosely
laid on top of the thermal insulatir,g layer 4. The outer final
layer is constituted by the roofing skin 6 of elastic, extensibl
roof sealing sheets tightly joined along their seams, made
for example, of soft PVC. The air interspace seal between the
individual layers remaining between the roofing skin 6 and the
understructure, and the mounting of the layers to the under-
structure, are achieved by the following means. The vapor
barrier sheet 3 is pulled over the upwardly extènding rim la
o the understructure in the upward direction and sealed with
respect to the understructure with the sealing strip 9 and to-
ward the outside with the sealing strip 10, for example of a
closed-cell soft foam material. The fixation of the layers
is effected in the edge zone by means of wooden planks 8
resting on the vapor barrier sheet 3 and attached to the under-
structure 1 b~ means of screws and dowels, these planks
simultaneously pressing the sealing strip 9 in place. The
wooden plank 8 corresponds in its thickness to that of the
thermal insulating layer 4. An anyular composite plastic-sheet-
metal profile 18 is attached by means of nails 19 to the
wooden plank 8 with the interposition of a further sealing
,
strip 11 wher~in the plastic-coated side of the profile 18
serves for firm welding onto the roofing skin 6. Pre~erahly,
the plastic coating of the profile 18 is like-~ise of so~ PVC
so that solution welding can be per~ormed in a simpl~ manner
in the zone 15. The upwardly projecting rim la of the under-
structure is likewise sealed additionally with the ~urther :~
thermal insulating layer 16 and the loose protective layer 17;
the composite plastlc-sheet-~.etal profile 12 constltutes; the
outer boundary of the edge~, this profile being attached with :
nails 14 to the rlm~la with the interposition of the sealing
strip 10; the plastic:-coated topside of this pro~ile serves:
for connecting the strip~13 of sealing sheet stock additionally t~
the roofing skin 6 by welding, thus ~orming the solution weld
seam 15. The strip~:13 bridg:es the:boundary zone from;pro~ile 12 .`
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to profile 18, to which latter~it is likewise welded with its:
other end, thus establishin~ the seaml~ess, ti~ht transition;~to
the roofing skin 6.~ ~While~the composite pla~ltic-sheet-metal
profiles 12, 18 produoe the mechanical fixati.on of the rooflng
skin and the ro~of construction to the understructure l, the:;
solution weld seams lS~a~s well as~the sealing strips~9,~10, 11,
which are provided, serve for sealing the interspace 36 between
the understructure l and the roofing skin 6.
Figure 2 shows an example for mounting and sealing a
roof aperture in the form of the roof gutter 20 with
downspout 21. Roo~ gutter 20 and downspout 21 are made, for
example, of hard~PVC and fitted one into the o~her with the
interposition of a gasket 2? to be vertically adjustablc. The
:roof gutter 20 rests with its sup~ortinq flange on the t~apor
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barricr film 3 and is extended through the aperture ~3 of the
understructure 1. The downspout 21 inserted in the roof
gutter 20 rests with its supportiny flange on the protective
layer 5 above the thermal insulating layer ~. The roofing
skin 6 is firmly and tightly joined to the supporting flange
of the downspout by solution welding in the zone 15. The roof
gutter 20 extended through the understructure 1 is sealed in the
region of the joint 23 between the roof gutter 20 and the aper-
ture 43, for example by a polyurethane foam sealing member
which, for example, is foamed in place at the building site.
Figure 3 shows the structure of a roo construction
for renovating an old bituminous roof with a loosely laid
roofing skin 6 and with the edge flashing. On the understructur
the existing roofing seal, for example a multiple-layer ~itumin-
ized pulpboard glued with bitumen, is provided, this roofing sea
also being joined to th, understructure 1, for example aerated
concrete. The thermal insulating layer 4 is then applied
loosely thereover, and this layer lS covered on the topside
with a protective layer S and the loosely laid roofing skin 6.
The fixation of the roofing skin 6 in the understructure is
achieved by means of the wooden plank 8 attached by means of
anchor nails 7 to the understructure 1 with the interposition
of the sealing strip 9. On the topside of the wooden plank 8,
the composite plastic-sheet-metal profile 18 is attached with
nails 19, the sealing strip 11 being interposed. On the
plastic-coated side of the profile 18, which side points up-
wards, the roofing skin 6 i5 firmly attached so that it
adheres to ~he plastic-coatcd side in the zone 15, for e~.ample
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by solution welding. The roof edge is formed by the roof
edcJe pro~ile 12 and the T-ed~e pro~ilc 27, which a~e attached
with the interposition of the sealing strip 10 by means of
hammer-type rivets 25 to the understructure. The strip 13 as
a supplement to the roofing skin 6, made of likcwise elastic
sealing sheet, bridges the edge zone and :is solution-welded
so that it adheres firmly to the composite plastic-sheet-metal
profile 12, as well as to the co~posite plastic-sheet-metal
profile 18 in the zone lS. With this construction of the edge
flashing of the roofillg skin 6 and the understructure 1, the
interspace 36 is safely sealed off sufficiently against air infl-
~from the outside. Additionally, an additional securement can
be effected at the ends of the seams by means of liquid film 26.
Figure 4 shows the fixation o:E the mounting ring 29
for a dome skylight to the understructure 1 and the tight
extension through the roofing skin and the understructure.
A protective layer 2 is placed, for example, on the understruc-
ture 1/ and on this layer rests the mounting ring 29 with its
supporting flange 29a ~ith the interposition of the sealing
strip 9.
Qn the outside of the mounting ring 29, the film
strip 13, corresponding in its composition of material to the
roo~ing skin 6, is adhesively mounted by means of an adhesive
layer 28. The mounting ring is subsequently attached to the
understructure 1 by means of nails 19 and by the placement of
flat composite plastic-sheet-metal strips 30. The composite
plastic-sheet-metal strips 30 serve for the firmly adhering
and tigllt mounting of the roofing skin 6, for example by means
of solution welding, in the zone 15. Additionally, end zones
can be sealed off by means of liquid film 26.
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~ i~ure 5 S]lowS a variatioll for the fasteni~lg of the
mounting ring 29 clnd sealing means on a flat roo~. In this
arrangement, the composite plastic-sheet-metal profile 31
is attachcd on the outside of the mounting ring 29 by means
of rivets 32; the outer, plastic-coated side of this profile
serves for connecting the roofing skin tightly and with firm
adhesion in the zone 15.
Pigures 6 and 7 show examples of arranyements for
the adhesive and tight mounting of the loosely laid roofing skin
in -the zone of a wall junction. In the illustrated example
according to Figure 6, an old roofing seal 24 applied over the.
entire area is still present on the understructure l; .a further
roofing skin 6, with the interposition of the protective layer 2
is at this point loosely laid thereon. The wall junction is
established by means of the composite plastic-sheet-metal
profile 33, attached to the understructure, for example
aerated concrete, with the interposition of a sealing strip 9
by means of anchor nails 7. The outwardly facing side of the
profile 33 is coated with plastic, so that welding or also
gluing of the roofing skin 6 to the profile 33 can be effected
in the zone 15. A modification of the wall connection is
shown in Figure 7, wherein no old roofing seal 24 is present,
but wherein the roofing skin 6 is extended at an angle upwardly
on the composite sheet-metal profile 33 and is solution~
welded in the zone 15 and secured by means of liquid film 26,
whereby the desired, adhesive and tight bond and the sealing
o the interspace 36 are accomplished.
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If roof constxuct:ions having an attic ~unction are
intended, then the invention can be put into practice as shown,
for example, in Figure 8. The mounting profile 35 is here
attached to the understructure la by means of the hammer-type
rivets 7 with the interposition of the sealing strips 9.
The composite plastic~sheet-metal profile 34 forming the edge
flashing is laid thereover, the roofing skin 6 being mounted
thereto in a firmly adhering and tight fashion, for example by
solution welding, in the zone 15. For sealiny purposesl sealing
strips can be employed made of an elastomer, neoprene, elastic
or plastic synthetic resins, closed-cell soft foam materials,
which are optionally also coated on one side with an adhesive
serving as the mounting aid~ However, elastic or elastic-plasti
putties can also be utilized, depending on the application site.
Figure 10 shows a basic diagram of a house 44 with
flat roof construction. The loosely laid roofing skin 6 covers
the roof surface and is sealed and fastened in the zones of
the roof edge 37 and of the roof cutouts, such as chimney 45
and mounting ring 29 for the dome skylight. Moreover, the
roofing skin 6 is alsG sealed with respect to the under-
structure.
