Waterproofing of walls using water-repellent plaster


I. NATURE OF THE
PROBLEM – REQUIREMENTS

Due
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.

 

II.
SOLUTION

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.

The
above mortars offer complete water repellence according to the DIN 18550
standard and at the same time they offer an aesthetically pleasant effect.

 


III.
APPLICATION

«Spatterdash»
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
coat»)

  1. 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.

  2. 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.

 

Application
of MARMOCRET Fine and MARMOCRET Decor

  1. 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.

  2. 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.
    Consumption
    of MARMOCRET Fine: approx. 7,5 kg/m2/5 mm of plaster thickness.
    Consumption
    of MARMOCRET Decor: approx. 10 kg/m2/5 mm of plaster thickness.

  3. The surface should be rubbed with a sponge float (when MARMOCRET
    Fine is
    applied) or a spiked float (when MARMOCRET Decor is applied) after sufficient
    setting has occurred.

 

Application of MARMOCRET-S

  1. 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.

  2. 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
    machine.
    Consumption
    of MARMOCRET-S: approx. 1,5 kg/m2/5 mm of plaster thickness (for the
    above mixing proportions).

  3. The surface should be rubbed with a sponge float after sufficient
    setting has occurred.

 

IV. REMARKS

  • During
    the application of the plaster, the temperature must be at least +50C.

  • During
    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.

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