Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~2~1Eii~7~7
Method for the making of self-plu~ g
and/or non-drip~2_roofi~_con__ _ction
The invention relates to the making of self-plugging
and/or non-dripping roofing construction.
A modern roof design normally includes a structure to
carry loads, insulation to control heat flow, a barrier
to control air and vapour flow, and a roofing element to
prevent water penetration.
Problems connected with leaks and dripping are known
to occur with more or less all types or roofs, but are
more prevalent with some roof designs than with others.
There are such factors as roof angle, type of insulation
or no insulation, type of roofing material, and obviously
the climate outside and inside, which have significant
bearing on the tendency for leaks and dripping from con-
densation of a particular building~
Buildings with flat or low-angle roofs in climates
with snow during winter or with heavy rains and high
humidity are particularly prone to develop leaks~ In-
dustrial buildings with a production process entailing
high humidity are particularly prone to dripping from
condensation.
On buildings with flat low-angle the roofs socalled
"built-up roofing" is the most common roofing type used.
~23l~
Built-up roofing is a continuous membrane covering
manufacturers on site from alternate layers of bitumen,
bitumen-saturated felts or asphalt-impregnated glass mats,
saturated and coated felts, and surfacings.
New materials have lately led to roofing materials of
single-ply or limited-ply membranes consisting of e.g. a
single-ply sheet of an elastomeric or plastic material.
~oofing membranes can also be liquid-applied as a
single or two-component system with polymeric fabrics or
glass-fibre reinforcements.
Whatever the type of roof and roofing construction
and material used, water leaks and condensation can occur,
particularly in the spring in cold climates when the snow
on the roof is melting, or during such heavy rainfalls
that the roof-gutters cannot cope with the amount of water
on the roof.
Water leakage and dripping for roofing constructions
can have considerable economic consequences, even when the
amount of water is small, for instance because the leakage
site is of very small size, perhaps only a small nail
hole. It is also extremely difficult to locate such
leakage sites, and more difficult the smaller the leak.
Similar problems can also be caused by condensation
as a result of not sufficiently effective insulation or
ventilation.
The object of the invention is to solve the above
mentioned problems and to provide a method which makes it
possible to achieve a self-plugging, i.e. a self acting
leak-stopping and/or non-dripping roofing construction.
According to one aspect of the invention there is
provided a method for making a basically waterproof
roofing construction self-plugging and non-dripping,
comprising the step of incorporating into the already
basically waterproof construction a layer comprising
viscosity-increasing and aqueous-gel forming material
chosen from the group consisting of the aqueous-gel
forming natural and synthetic hydrophilic polymers and
inorganic hydrophilic substances that form gels with
water, whereby holes made by nails and cracks that may
form upon weathering are self-plugged by said layer and
dripping is prevented by water absorption and swelling
of said layer.
According to another aspect of the inven~ion there
is provided a basically waterproof roofing construction
that is also self-plugging and non-dripping, comprising
the combination with an already basically waterproof
construction of a layer comprising viscosity~increasing
and aqueous-gel forming material chosen from the group
consisting of the aqueous-gel forming natural and syn-
thetic hydrophilic polymers and inorganic hydrophilic
substances that form gels with water, whereby holes
made by nails and cracks that may form upon weathering
are self-plugged by said layer and dripping is prevented
by water absorption and swelling of said layer.
The present invention solves these problems in a
simple and economic way by making use of the special
properties which hydrophilic polymers and/or certain
hydrophilic inorganic substances possess for increasing
the viscosity of water to such an extent that it will
not drip from the roofing construction, and/or to bind
the water in the form and consistency of a gel. Such
polymers and inorganic substances can also be brought
to swell by water to such an extent that a leakage is
stopped by itself.
The hydrophilic polymers which can be used with the
method, can either be water-soluble or water~swellable, or
a combination of both. The same applies for the inorganic
substances. Water-soluble polymers and/or water-soluble
inorganic substances of the aforementioned type can be
made non water-soluble through partial cross-linking, i.e.
cross-linking which leaves a number of hydrophilic groups
free to bind water molecules.
;
The hydrophilic polymers and/or inorganic hydrophilic
substances can be incorporated in many different ways in
the roofing construction:
1) either by being applied to the deck as a coating, or
2) applied as a coat on the overside or the underside
of the membrane, e.g. organic felt, asbestos ply felt,
fiber-glass mats or base sheets, shingles, elastomeric or
plastic film and sheeting etc., or on another component
of the roofing construction, or
3) in the form of a film, sheet, mat, loose powder etc.
by being laid out over or under another component of the
roofing construction, or
4) by being incorporated in the membrane whatever the
type, e.g. in a felt or sheet, or
5) by being applied on or in other ways attached to other
components which are part of the roofing construction.
Examples of hydrophilic polymers which can be used for
the method are natural hydrophilic polymers such as gum
arabic, tragacanth and karaya, semi-synthetic hydrophilic
polymers such as carboxymethylcellulose, methylcellulose
and other cellulose ethers, lignin derivatives, various
kinds of modified starches (ethers and acetates), and
synthetic hydrophilic polymers such as polyacrylic
acids, polyacrylamides, and polyethyleneoxide, polyvinyl
pyrrolidone, polyethyleneimine and others, as well as
combinations of such polymers or with other substances.
As examples of inorganic substances, which can either
be used alone to hind water in the form of a ~el or
a highly viscous fluid, can be mentioned water glass,
alumina, magnesia, bentonite etc. and mixtures of such
inorganic hydrophilic substances or mixtures of these
and hydrophilic polymers.
The mentioned hydrophilic polymers and/or hydrophilic
inorganic substances can eventually be cross-linked,
either in the form of a pre-crosslinked film or sheet or
similar or a layer cross-linked in situ. As an example
~2~L~7~'7
of the former can be mentioned "Dow Water Absorbent
Laminate" and of the latter a mixture of lignosulfonate
and dichromate.
There is an extensive patent and other literature
treating viscosity-increasing or gel-forming polymers
and inorganic substances, particularly within the fields
of grouting and oil drilling. This may be a major part of
such polymers and inorganic substances could find appli-
cation with the method of the present invention with the
necessary adjustments.
