POLOPPOSTO MANUAL USE DEUTSCHE ENGLISH | страница 6

It is the inverted poles between water molecules and the
masonry that causes water molecules to move upwards
(“magnet effect”): polarity inside dry masonry captures
salty water molecules existing in the foundations, which
have opposite polarity, causing them to rise up through the
porous materials the masonry is made of.
It should also be considered that rising damp causes mineral
salts to move upwards and deposit inside the masonry
affected. Mineral salts, which are normally present in the
ground and in building materials, are water-dissolved and
rise through the masonry up to the evaporation zone.
It is precisely the continuing evaporation of the water
contained in this solution that allows salts to deposit next
to the wall surface, helping crystallization while increasing
their volume which damages the superficial layers of walls
(plaster and paint) and/or creates wet stains.
The presence of salts is a contributing factor to rising damp
itself, since those salts help generate a vertical electric
potential difference inside the masonry and strengthen
water molecule polarization.
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SYMPTOMS OF RISING DAMP
Visible symptoms:
• plaster degradation (peeling, “crumbling”) and/or paint
flaking;
• salt efflorescence on wall surface;
• hygroscopic wet stains (caused by the presence of
salts);
• paint blisters (due to salt crystallization causing paint to
detach from masonry).
Smell and perceptive symptoms:
• smell of mould of bad odour caused by the reaction
of water evaporating from masonry with the materials
masonry is made of;
• high heating costs: humid masonry has its insulation
power dramatically reduced and conducts heat from
inside the building to the outside.
• feel of cold: body heat is captured by cold and humid
masonry causing a feel of cold, even with relatively
high room temperatures.
Either only one of the signs listed or more than one can
suggest that it is really rising damp. Of course none of these
are reliable indicators of this phenomenon on their own, as
other causes of dampness may show the same signs.
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However, capillary action can explain modest damp rise -
some centimetres - not tenths of centimetres or metres. In
order to explain the evident phenomenon of rising damp,
it is important to know that there is a difference in electric
potential inside masonry, which can be detected - using a
special tool - between the humid wall base and its upper
part, which has not been hit by damp yet.