Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MOISTURE AND WEATHER PROOFING MEMBRANE AND PROCESS
THEREFOR
FIELD OF THE INVENTION
The present invention generally relates to protective membranes used in the
construction of buildings. More particularly, it relates to a roofing,
moisture
proofing and weather proofing membrane and to the manufacturing process of
such membrane.
BACKGROUND OF THE INVENTION
Moisture and weather proofing membranes are commonly used in the
construction field, mainly to protect the roofs from water leaks, which cause
problems of moisture. These membranes are typically manufactured using
fibrous web coated with a weather resistant bituminous coating material.
Already known in the prior art, there is a bitumen membrane comprising a
carrier
layer made of glass fiber sandwiched between two layers of bitumen. The
membrane is installed on the roof and a finish covering is installed thereon.
As
well known in the art, the infiltration of water may come from the outside, or
the
inside, of the building in the form of vapour. A drawback encountered with
such
a prior art membrane is that, even though it may prevent an infiltration of
water
from the outside, it also prevents the water and air from the inside to escape
from the roof, thereby causing a vapour pressure underneath the membrane.
This problem of underneath infiltration of air and humidity is well discussed
in US
patent no. 4,992,315, where it is mentioned that moisture vapour from
different
sources can cause formation of bubbles and subsequent leaks in the bituminous
waterproofing layer, especially on hot days when the water vapour is caused to
expand due to the heat. There is a bituminous roofing membrane known in the
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prior art that reduces in some way the effect of that problem of underneath
vapour pressure. That membrane is a laminated membrane comprising a
reinforcement layer sandwiched between two layers of bitumen. The membrane
further comprises a layer of sand covering one of the bituminous layers and
strips of self-adhesive bitumen added on the layer of sand. The vapour
pressure
from underneath the membrane can escape therefrom by diffusion between the
strips of self-adhesive bitumen. This prior art membrane however shows some
drawbacks. For example, one of the problems is that when the temperature gets
very high, the bitumen of the bituminous layer eventually runs through the
layer
of sand and the membrane becomes fully adhered to the substrate and loses
its performance.
Other examples of roofing membranes are shown in Canadian patent
application no. 2,022,442; Canadian patent no. 1,124,143; US Des.
No. 297,465; US patents nos 3,890,263; 4,342,804; 4,343,847; 4,481,245;
4,659,759; 4,983,426; 4,992,315; 5,055,135; 5,110,674; 5,143,766; 5,182,319;
5,311,716; 5,437,923; 5,439,726; 5,695,373; 5,787,668; 5,843,522; 5,848,510;
5,865,549; and 6,044,604.
SUMMARY OF THE INVENTION
An object of the present invention is to propose an improved moisture and
weather proofing membrane, and a process for manufacturing the same.
Another object of the present invention is to provide a roofing membrane that
allows air and humidity trapped thereunder to easily escape without damaging
the membrane.
In accordance with that object, the present invention proposes a moisture and
weather proofing membrane comprising a carrier layer having opposite top and
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under faces, a waterproof layer made of a waterproof material coating the top
face of the carrier layer; and spaced self-adhesive bituminous pieces bonded
to
the under face of the carrier layer. The bituminous pieces are saturating at
least
in part the carrier layer. The membrane further comprises interconnected
spaces
of uncoated carrier layer between the self-adhesive bituminous pieces.
According to a preferred feature, each of the bituminous pieces adheres to the
waterproof material of the waterproof layer. Also preferably, the waterproof
material of the waterproof layer saturates the carrier layer partially.
As can be appreciated, these interconnected spaces of uncoated carrier layer
act as bond breakers, and thereby allow the diffusion of vapour pressure
formed
underneath the membrane once installed on a substrate. Also, thanks to the
fact
that the self-adhesive bituminous pieces saturate the carrier layer, meaning
that
they penetrate or impregnate the carrier layer, no vapour or water can seep
between those pieces and the carrier layer.
The bituminous pieces preferably consist of broken bituminous strips extending
substantially in parallel to each other.
The present invention also proposes a process for making a membrane as
described above which comprises the steps of:
a) providing a sheet of carrier material;
b) coating a top face of said sheet with a waterproof material; and
c) applying on the under face of the sheet, pieces of self-adhesive bitumen
saturating at least in part the carrier material.
Preferably, in step c) the pieces of self-adhesive bitumen are adhering to the
waterproof material of the top face. Also preferably, in step a), the
waterproof
material is saturating partially the carrier material.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a bottom view of a membrane according to a preferred embodiment
of the present invention showing the underside of that membrane.
Figure 2 is a cross-sectional side view of the membrane shown in figure 1
along
line II-II.
Figure 3 is a schematic view showing a process for making a membrane
according to the present invention.
Figure 4 is a perspective view of a roller used for applying the strips of
self-
adhesive bitumen on the underside of the membrane.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to figures 1 and 2, a roofing, moisture proofing and weatherproofing
membrane (10) according to a preferred embodiment of the invention is
illustrated. The membrane (10) can be installed on a substrate, such as a
roof,
to protect the same from water infiltration or other bad weather such as
freezing
and thawing, humidity, etc. The membrane (10) is composed of a carrier layer
(12) that acts as a reinforcement layer. The carrier layer (12) has a top face
coated with a waterproof material (16). The carrier layer (12) is preferably
made
of a sheet of glass fiber but any other material commonly used in the prior
art as
the reinforcement layer can be used.
A plurality of spaced self-adhesive bituminous pieces (14) are applied and
bonded to the under face of the carrier layer (12), leaving therebetween
interconnected spaces (13) of uncoated carrier layer. The pieces (14) of self-
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adhesive bitumen allow the membrane (10) to be fixed by bonding to the
substrate, whereas these interconnected spaces (13) of uncoated carrier layer
act as bond breakers and thereby allow the diffusion of vapour pressure formed
underneath the membrane once it is installed on a substrate. The arrows on
5 figure 1 show an example of a path that can be followed by the vapour to
escape from underneath the membrane (10). According to a preferred
embodiment which provides a better attachment and which better prevents the
vapour or water from seeping between the bituminous pieces (14) and the
carrier layer (12), the bituminous pieces (14) and the density of the carrier
layer
(12) are chosen so that during application of the bituminous pieces (14), the
bitumen saturates the carrier layer (12) and adheres to the waterproof
material
(16) coating the top face.
More preferably, the carrier layer (12) is made of fiberglass having a fiber
density
greater than about 100g/cm3 and less than about 150 g/cm3, more or less 5
g/cm3. Most preferably, the fiber density is about 130 glcm3.
A finishing layer such as a thermoplastic film (29) is preferably covering the
waterproof layer (16) and that, especially if the waterproof material is
sticky. The
finishing layer could also be made of any material selected from the group
consisting of a thermoplastic film, sand, talc, and granules.
The membrane (10) is a semi-adhered self-adhesive sheet that can be used
over all substrates such as a roof. Since the membrane (10) adheres only
partially to the substrate, it can be installed directly on insulation boards
without
an intermediate board.
According to the preferred embodiment illustrated, the bituminous pieces (14)
are broken bituminous strips (14) extending in parallel to each other along a
longitudinal direction of the membrane (10). Also preferably, each broken
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bituminous strip (14) consists of a plurality of longitudinally aligned bands
(18)
separated by gaps (20) of uncoated carrier layer (12). The gaps (20) of each
strip is in a non aligned relationship with the gaps (20) of an adjacent strip
so to
provide a better path for the escaping vapour.
It should be understood that another embodiment of the invention, not
illustrated, may advantageously have an infinite number and width of self-
adhesive bituminous pieces having another shape than the one illustrated, as
long as these pieces allow the membrane to be bonded to the substrate and the
formation of the bond breaker consisting of an uncoated carrier layer. Other
examples of shapes that can be used could be circular, triangular, elliptical,
etc.
The waterproof layer (16) is preferably made of a material selected from the
group consisting of bitumen, bitumen modified with a polymer selected from the
group consisting of SBS, SIS,SB, SEBS and APP, and oxidized asphalt. Most
preferably, it is a modified bitumen. It is also preferably chosen so that it
can
saturate partially the carrier layer during the application of the waterproof
layer
(16) so to better adhere with the bitumen of the bituminous stripes (14)
saturating also the carrier layer (12). The bituminous self-adhered pieces
(14)
saturate, that is to say penetrate, the carrier layer (12) and thus prevent
the
vapor and water from seeping between these pieces (14) and the carrier layer
(12). The membrane (10) is unique in that it uses an unsaturated portion of
the
carrier (12) as the bond breaker. By doing this, the diffusion of vapour
pressure
is superior and also the possibility of bonding at a future date is virtually
eliminated.
The membrane (10) can be offered in any thickness, and in a variety of
finishes
on the top surface, such as a film, sand, talc or granules. A variety of
finishes on
the under side could be used, such as a siliconised release film,
thermofusible
plastic film or any other surfacing suitable for installation.
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The bitumen can be modified with any polymer such as: SBS, SIS, SB, SEBS,
APP, etc. Oxidized asphalt or any product suitable for waterproofing could
also
be used. The reinforcement layer is preferably a sheet of glass fibre, but
could
also be any other material commonly used in the prior art as reinforcement.
Referring to figure 3, a preferred version of a process according to the
invention
is schematically illustrated. As can be appreciated, the process comprises the
steps of: a) providing a sheet (12) of carrier material; b) coating the top
face (19)
of the sheet (12) with a waterproof material (16), preferably modified
bitumen;
and c) applying on the under face (15) of the sheet (12) strips (14) of self-
adhesive bitumen (17). More particularly, a roll (21) of carrier material is
unrolled, and soft or liquefied modified bitumen (16) is applied on the top
face
(19). The sheet (12) with the soft bitumen (16) thereon is passed through
press
rollers (20) to spread the bitumen and saturate the carrier material
partially.
The strips of self-adhesive bitumen are applied on the under face (15) of the
sheet (12) by bringing the same into contact with the surface of a roller (22)
soaking in a pool (24) containing liquefied self-adhesive bitumen (17). The
surface of the roller (22) has a given relief that allows the self-adhesive
bitumen
to be applied on the under face (15) of the sheet (12), as broken strips. More
specifically, as shown in Figure 4, the roller (22) has a surface (26)
including a
plurality of elongated bands (28) projecting from the surface (26). The roller
(22)
is thus soaked and rolled in the pool (24) such that a portion of the roller
(22) is
coming out from the liquid, as shown in Figure 3. The sheet (12) is passed
over
the roller (22) and the under face thereof is brought in contact with the
portion
of the roller (22) coming out of the liquid, thereby applying thereon broken
strips
of self-adhesive bitumen which saturate, in other words penetrate, the carrier
material and adhere to the waterproof material (16) coating the top face.
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The method preferably comprises the additional step of d) covering the
waterproof material (16) with a finishing layer.
The waterproof material used to cover the top face is preferably selected from
the group consisting of bitumen, bitumen modified with a polymer selected from
the group consisting of SBS, SIS, SB, SEBS and APP and oxidized asphalt, and
the carrier material is preferably fiber glass, but could also be any material
commonly used in the prior art as reinforcement.
Although a preferred embodiment of the present invention has been described
in detail herein and illustrated in the accompanying drawings, it is to be
understood that the invention is not limited to this precise embodiment and
that
various changes and modifications may be effected therein without departing
from the scope or spirit of the present invention.
