Waterproofing of walls using water-repellent render
MARMOCREΤ-BOND Mortar for bonding spatterdash of render
MARMOCREΤ-BASE Base layer render
MARMOCRET-PLUS Fine Polymer-modified, colored, water-repellent, cement-based render – Smooth finish
MARMOCRET-PLUS Decor Polymer-modified, colored, water-repellent, cement-based render – Rough-textured finish
PL-PRIMER Plaster primer – Dehydration barrier
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 render.
The use of MARMOCRET PLUS Fine or MARMOCRET PLUS Decor polymer-modified, white or colored, water-repellent cement-based renders (depending on whether a smooth or rough wall surface is desired).
The above mortars offer high water repellence 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.
25kg of MARMOCRET-BOND are added into 4.75l of water under continuous stirring, until a mortar of the required workability is formed. The mortar is applied with a rendering machine or by hand, using a trowel. The basic layer of render can be applied 1-2 days after the application of MARMOCRET-BOND.
Consumption of MARMOCRET-BOND: approx. 5kg/m².
Rendering (“Brown coat” – “Floating coat”)
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.
25kg of MARMOCRET-BASE are added into 4.75 l of water under continuous stirring, until a mortar of the required workability is formed. The mortar is applied with a rendering machine or by hand, with a float or trowel. The final coat of render should be applied at least 7 days after the application of MARMOCRET-BASE.
Consumption of MARMOCRET- BASE: approx. 13.5 kg/m²/cm of render thickness.
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 render around these surfaces and the different contraction-expansion coefficient of the distinct layers.
The fiberglass 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 render, the render should be well dampened to reduce water immigration from the render mixture to the undercoat. In case colored MARMOCRET-PLUS Fine or MARMOCRET-PLUS 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-PLUS Fine and MARMOCRET-PLUS Decor
25kg of MARMOCRET-PLUS Fine or MARMOCRET-PLUS Decor are added into 5.0-5.5l of 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 render.
The render may be applied with a float or trowel or by using a plastering machine.
Consumption of MARMOCRET PLUS Fine: approx. 1.4 kg/m²/mm, recommended thickness 2-3 mm.
Consumption of MARMOCRET PLUS Decor: approx. 1.4 kg/m²/mm, recommended thickness 2.5-3.5 mm.
The surface should be rubbed with a sponge float (when MARMOCRET-PLUS Fine is applied) or a plastic or wooden float (when MARMOCRET-PLUS Decor is applied) after sufficient setting has occurred. Working time depends on the substrate absorptivity, ambient temperature and workability of the mixture.
During the application of the render, the temperature must be at least +5οC.
During the summer months, it is recommended that the render is dampened after its application, in order to be protected from dehydration due to high temperature.
The products contain cement and react with water forming alkaline solutions, thus is classified as irritant.
Consult the directions for safe use and precautions written on the package.