Waterproofing of walls using water-repellent plaster
I. NATURE OF THE
PROBLEM – REQUIREMENTS
to rain, moisture problems at external walls are a usual phenomenon, which,
however, may be confronted easily and effectively from the beginning, during the
application of plaster.
a) The use of MARMOCRET Fine or MARMOCRET Decor decorative, water-repellent,
premixed white or colored plasters
(depending on whether a smooth or coarse wall surface is desired).
b) The use of MARMOCRET-S binder
mortar for the preparation of white water-repellent plaster.
above mortars offer complete water repellence according to the DIN 18550
standard and at the same time they offer an aesthetically pleasant effect.
The substrate should be free of dust, grease, loose particles
etc. and well dampened with water. A traditional spatterdash is then applied,
which should be reinforced in tough or very smooth surfaces (e.g. extruded
polystyrene boards etc.) with ADIPLAST polymer building latex (cement : sand :
ADIPLAST : water = 1 : 1 : 0,25 : 0,25 by volume) in order to improve key
bonding of the spatterdash to the above surfaces. Instead of the traditional
spatterdash layer, the premixed mortar MARMOCRET-BOND can be used.
Rendering (“Brown coat” – “Floating
After the spatterdash has dried, a traditional rendering
coat is applied (“brown coat”) in order to even out the surface
and repair possible imperfections on the wall. Instead of the
traditional undercoat layer, the premixed mortar MARMOCRET-BASE can be used.
In case the substrate is made of thermoinsulating layers (polystyrene,
polyurethane etc.) as well as on beams, columns, concrete walls, coursing
joints etc., reinforcing with fibreglass mesh is recommended during
rendering in order to prevent cracking due to increased thermal load imposed
on the plaster around these surfaces and the different contraction-expansion
coefficient of the distinct layers.
The fibreglass mesh is lightly pressed on the fresh rendering layer and
extends 10-15 cm beyond the covering area of the thermoinsulating boards.
Before applying the plaster, the render should be well
dampened to reduce water immigration from the plaster mixture to the
undercoat. In case colored MARMOCRET Fine or MARMOCRET Decor is used,
instead of dampening it is recommended to prime the substrate with PL-PRIMER
to reduce absorptivity and secure color uniformity over the whole surface.
Consumption of PL-PRIMER: 40-100 g/m2, depending on the
absorptivity of the substrate.
of MARMOCRET Fine and MARMOCRET Decor
MARMOCRET Fine or MARMOCRET Decor is added into clean water under continuous
stirring, until a mixture with the desired workability is formed. The mixer used
must be clean, in order to avoid possible color alteration of the plaster.
Application of MARMOCRET Fine or MARMOCRET Decor
as a finishing (setting) coat of plaster, at a thickness of approx. 5 mm. The plaster may be
applied with a float or trowel or by using a plastering machine.
of MARMOCRET Fine: approx. 7,5 kg/m2/5 mm of plaster thickness.
of MARMOCRET Decor: approx. 10 kg/m2/5 mm of plaster thickness.
The surface should be rubbed with a sponge float (when MARMOCRET
applied) or a spiked float (when MARMOCRET Decor is applied) after sufficient
setting has occurred.
Application of MARMOCRET-S
The content of one 15 kg bag of MARMOCRET-S should be mixed with approx.
70 kg of fine marble aggregates and 18 kg of water. The mixer used must be
clean, in order to avoid possible color alteration of the plaster.
Application of MARMOCRET-S as a finishing (setting) coat of plaster, at a thickness of about
5 mm. The plaster may be applied with a float or trowel or by using a plastering
of MARMOCRET-S: approx. 1,5 kg/m2/5 mm of plaster thickness (for the
above mixing proportions).
The surface should be rubbed with a sponge float after sufficient
setting has occurred.
the application of the plaster, the temperature must be at least +50C.
the summer months, it is recommended that the plaster is dampened after its
application, in order to be protected from dehydration due to high temperature.