Note: Descriptions are shown in the official language in which they were submitted.
CA 021215502 2004-10-05
1
Vapour Retarder for Use in Heat Insulation of Buildings
The invention relates to a vapour barrier, arranged room
oriented, for use in heat insulation of buildings, especially
for heat insulation measures in new buildings and in the
renovation of old buildings.
In order to reduce the carbon dioxide emission which occurs due
to heating of buildings, heat insulation measures are carried
out in the construction of new buildings and in the renovation
of old buildings. For economic reasons which constantly have
to be considered by the owner of the building, the question of
costs also has to be taken into account here. Moreover, the
outer appearance of the building is here a significant factor
which likewise represents a limit to what can actually be done.
Thus, for example, heat insulation measures of this kind can
only be carried out on buildings which have a framework visible
through insulation layers lying on the inside. The acceptable
amount of moisture in the framework wood must also be ensured
especially under winter conditions by the possible diffusion
of vapour and also by the vapour barrier room-oriented. In
contract to this, the rain moisture penetrating in the summer
months through the joints between the wooden posts and the
CA 02215502 2003-12-22
2
nogging must be able to dry out towards the inside as well, in
order to guarantee long life for the wood used in the
framework.
Similar difficulties also arise in the subsequent complete
rafter insulation on high-pitched roofs with a vapour-tight
front covering (e. g. roofing fabric on planking). Thus tests
carried out by the Fraunhofer Institut fur Bauphysik showed
that where vapour barriers were applied inside with a water
vapour diffusion resistance (Sd-value) which is smaller than 10
m diffusion-equivalent air space width, especially on roofs
oriented towards the north, the extent to which the planking
dries out in summer is not sufficient to achieve a wood
moisture situation which is harmless. Thus vapour barriers
which are applied room-oriented can no longer to an adequate
extent carry away moisture accumulations which are caused by
convection, for example.
Proceeding from these known advantages, it is one feature of
the invention, in preferred forms, to create a vapour barrier
arranged room-oriented which is in a position, under different
conditions, variable in use, to guarantee a water vapour
diffusion between the space air and the interior of a building
component such as will to as large an extent as possible
prevent damage of the building material used being caused by
moisture.
In accordance with an embodiment of the present invention,
there is provided, a water vapor exchange system for use in
building insulation comprising (i) a fiber insulation and (ii)
a vapor retarder selected from (a) a film comprising polyamide
with a thickness of 20um to 100um and (b) a polymer coating
applied to a carrier material; the film or the coating having
a water vapor diffusion resistance (sd-value) at a relative
CA 02215502 2003-12-22
3
humidity of an atmosphere surrounding the vapor retarder in the
region of 30$ to 50~ of 2 to 5 meters diffusion-equivalent air
layer thickness, and, at a relative humidity in the region of
60$ to 80~ which is < 1 meter diffusion-equivalent air-layer
thickness.
In accordance with another embodiment of the present invention
there is provided vapour retarder for use in water vapor
exchange systems used in building insulation, the vapor
retarder comprising a film comprising polyamide or a polymer
coating applied to a carrier material having a water vapor
diffusion resistance (sd-value) at a relative humidity of an
atmosphere surrounding the vapor retarder in the region of 30~
to 50~ of 2 to 5 meters diffusion-equivalent air layer
thickness, and, at a relative humidity in the region of 60~ to
80$ which is < 1 meter diffusion-equivalent air layer
thickness.
In accordance with a further embodiment of the present
invention there is provided a water vapor exchange system
comprising (i) thermal insulation and (ii) a film or a polymer
coating applied to a carrier having a water vapor diffusion
resistance (sd-value) at a relative humidity of an atmosphere
surrounding the vapor retarder in the region of 30$ to 50$ of
2 to 5 meters diffusion-equivalent air layer thickness, and,
at a relative humidity in the region of 60g to 80~ which is <
1 meter diffusion-equivalent air layer thickness.
In accordance with a yet further embodiment of the present
invention there is provided a method for providing a vapor
barrier to a building, comprising installing a film or a
polymer coating applied to a carrier on at least a part of the
building, wherein the film has a water vapor diffusion
resistance (sd-value) at a relative humidity of an atmosphere
CA 021215502 2004-10-05
3a
surrounding the vapor retarder in the region of 30o to 500 of
2 to 5 meters diffusion-equivalent air layer thickness, and,
at a relative humidity in the region of 60o to 80o which is <
1 meter diffusion-equivalent air layer thickness.
In accordance with one embodiment of the present invention
there is provided in a method of building construction or
renovation, the improvement comprising applying a film to a
structure of the building, wherein the film has a water vapor
diffusion resistance (s,,-value) at a relative humidity of an
atmosphere surrounding the vapor retarder in the region of 300
to 500 of 2 to 5 meters diffusion-equivalent air layer
thickness, and, at a relative humidity in the region of 60o to
80o which is < 1 meter diffusion-equivalent air layer
thickness.
In accordance with another embodiment of the present invention
there is provided a building structure, comprising a film
attached to the building structure, wherein the film has a
water vapor diffusion resistance (s~,-value) at a relative
humidity of an atmosphere surrounding the vapor retarder in the
region of 30as to 50'~ of 2 to 5 meters diffusion-equivalent air
layer thickness, and, at a relative humidity in the region of
60'~ to 80'a which is < 1 meter diffusion-equivalent air layer
thickness.
In accordance with a further embodiment of the present
invention there is provided a roof of a building, comprising
a film attached to the roof of the building, wherein the film
has a water vapor diffusion resistance (s~-value) at a relative
humidity of an atmosphere surrounding the vapor retarder in the
region of 30~ to 50'~ of 2 to 5 meters diffusion-equivalent air
layer thickness, and, at a relative humidity in the region of
60~ to 80'~ which is < 1 meter diffusion-equivalent air layer
CA 021215502 2004-10-05
3b
thickness.
The film, in a preferred embodiment, is selected from the
groups consisting of nylon-6, nylon-4 and nylon-3.
In another preferred embodiment, the material of the vapour
barrier is a support material having a polymer coating applied
thereto. The polymer coating can be selected from the group
consisting of polyvinyl alcohol, a synthetic-polymer
dispersion, methylcellulose, linseed oil alkyd, bone glue and
protein derivatives.
In a further preferred embodiment, the material used for the
vapour barrier is applied as a coating on a support material
with a low water-vapour diffusion resistance.
In another preferred embodiment, the material is placed so as
to form a sandwich between two layers of a support material
with low water-vapour diffusion resistance. Preferably, the
support material is selected from fiber-reinforced cellulose
materials.
The vapour barrier according to the invention, which can also
be termed "humidity-adaptive vapour barrier" uses as an
essential material one that has a water vapour diffusion
resistance dependent on the ambient humidity and has sufficient
tensile and compressive strength to be used in buildings as
they are being built.
The material used for the vapour barrier, in the form of a film
or as a coating on a carrier material, should have, with a
relative humidity of the atmosphere surrounding the vapour
barrier between 30'as and 50'a, a water vapour diffusion
resistance value (S,j-value) of 2 to 5 m of a diffusion-
CA 02215502 2004-10-05
3c
equivalent air space width, and with a relative humidity in the
region of 60 o to 80 0, such as is typical for the summer months,
for example, a water vapour diffusion resistance (Sd-value)
which is smaller than 1 m diffusion-equivalent air space width.
20
CA 02215502 1997-09-16
,
4
'. This leads to a higher water vapour diffusion
resistance being achieved under winter conditions than
under summer conditions. In this way, the drying out
process in the summer can be favoured without the
moisture supply under winter conditions being able to
assume a value which can cause damage to the materials
used and to the building itself.
In addition to the applications alr-eady mentioned with
the disadvantages of the state of the art, the
invention can also be used on metal roofs or timber
post constructions and there, too, can lead, in
addition to an improvement in the heat insulation, to a
reduction of the building costs.
As a material for the vapour barrier having the desired
properties it is possible to use, for instance a
polyamide 6, a polyamide 4 or polyamide 3, as they are
known in particular from BIEDERBICK, K., "Kunststoffe -
kurz and bu.ndig", Vogel-Verlag ~nliirzburg. These
polyamides are inserted as films and inherently have
the required characteristics in relation to water
vapour diffusion resistance. Moreover, they have the
strengths necessary for use in buildings, and can thus
be used without any additional outlay. The thickness
of the films can be in the region of 10 ~,un to 2 mm,
preferably in the region of 20 Eun to 100 dun.
CA 02215502 1997-09-16
. , .
".. However, other materials may also be used which do not
have adequate strength and may be applied to suitable
carrier materials. The carrier materials here
preferably have a low water vapour diffusion resistance
5 and the required characteristics of the vapour barrier
according to the invention are essentially provided by
the coating.
Fibre reinforced cellulose materials, such as paper
webs, films made of synthetic fibre spun fabrics or
even perforated polyethylene films, for example, may be
used as materials for the carrier or carriers.
The material can also be present as a coating on a
carrier material. The coating can here be applied to
one side of the carrier material but also in special
cases be received between two layers of carrier
material like a sandwich. In the latter case, the
coating material is effectively protected from both
sides against being worn away mechanically and can
therefore guarantee the desired water vapour diffusion
over a long period of time. A plurality of layer
constructions can also be constructed, laid one above
the other.
Different substances and materials can be used for the
coating of the carrier material. Thus polymers, such
as, for example, modified polyvinyl alcohols, can be
applied with appropriate coating processes. Here the
' CA 02215502 1997-09-16
6
'_ water vapour diffusion resistance varies, measured
according to DIN 52615, by more than the power of ten
between a dry and a damp environment.
However, dispersed synthetic resins, methyl cellulose,
linseed oil alkyd resin, bone glue or protein
derivatives can also be used as coating material for
the carrier.
where the carrier material is coated on one side, this
coating can be applied on the side on which no
protection, or only very little, is required against
mechanical influences. The mounting of the vapour
barrier according to the invention can in this case be
done in such a way that the protective carrier material
shows towards the side facing the space or towards the
side turned away from the space.
The invention is to be described in greater detail
below by means of an example.
The vapour barrier according to the invention is here
formed solely from a film which consists of polyamide
6. Experiments were carried out with a film thickness
of 50 Eun. The polyamide 6 films used are currently
manufactured by the firm MF-Folien GmbH in Kempten,
Germany.
CA 02215502 1998-O1-13
7
Hygroscopic Behaviour in the Laboratory Test
The water vapour diffusion resistance of the humidity-
adaptive vapour barrier was determined according to DIN
52 615 in the dry region (3/50 % relative humidity
(relative humidity)) and in the damp region (50/93 %
relative humidity) as well as in two damp regions lying
in between (33/50 % and 50/75 relative humidity). The
result for the diffusion-equivalent air space width (sd-
value) of the vapour barrier with a thickness of 50 ~m
is represented in Figure 1 in dependence on the average
relative humidity prevalent in the test. The
difference between the sd ~ value in the dry region and
that in the damp region is more than the power of ten,
so that under practical space air conditions which move
between 30 % and 50 % in winter and between roughly 60
and 70 % in summer it can be expected that the
diffusion streams can be clearly controlled by the
vapour barrier.
An Example of a Practical Application
Mathematical tests have shown that high-pitched roofs
with vapour-tight secondary roofs, after the
installation of a complete inter-rafter insulation made
of mineral fibre 10 cm to 20 cm thick, can become so
damp within a few years despite a vapour barrier room-
oriented that damage is unavoidable. The situation
is particularly critical with high space air humidities
which vary, for example between 50 %
CA 02215502 1998-O1-13
8
relative humidity in January and 70 % relative humidity
in July when at the same time the short-wave radiation
gain through northerly orientation is relatively low.
The influence of the humidity-adaptive vapour barrier
on the long-term moisture balance of such constructions
under the climatic conditions of Holzkirchen is
therefore estimated below with the aid of a method
which has already been verified several times in
experiments.
Proceeding from an non-insulated high-pitched roof (28°
pitch) orientated towards the north and with planking,
bituminized felt and tile covering, which roof is in
hygroscopic equilibrium with its surroundings, the
behaviour of the humidity after the installation of
inter-rafter insulation with a traditional vapour
barrier and with the humidity-adaptive vapour barrier
room-oriented is shown in Fig. 2. The course
of the overall humidity in the roof is indicated above
and the course of the wood moisture of the planks is
indicated below, over a period of ten years. Whilst
the humidity in the roof with the traditional vapour
barrier quickly rises with seasonal fluctuations, with
wood moisture values (> 20 M.-%) giving cause for
concern long-term already occurring in the first year,
in the roof with the humidity-adaptive vapour barrier
no moisture accumulation can be detected. In the
summer the wood moisture falls constantly below 20 M-%
' CA 02215502 1997-09-16
9
there, such that no moisture damage is to be feared
here.
The humidity-adaptive vapour barrier thus opens up the
possibility of insulating high-pitched roofs on old
buildings without great risk of damage.
15
25
