Application of colored, water-repellent render for preparation of coarse surfaces

RELATED MATERIALS

MARMOCRET Decor Pre-mixed, water-repellent render. Rough-textured finish

MARMOCRET-BOND Mortar for bonding spatterdash of render

MARMOCRET-BASE Pre-mixed render for the base coat

PL-PRIMER Render primer – Dehydration barrier

ADIPLAST Polymer latex for multiple improvements of mortars

FIBERGLASS MESH Fiberglass mesh for render reinforcing

 

I. NATURE OF THE PROBLEM – REQUIREMENTS

The overlay of a building’s facade consists one of it’s characteristic architectural features. Therefore, they must present an aesthetically pleasing finish and, at the same time, be resistant to adverse weather conditions.

II. SOLUTION

The use of MARMOCRET Decor to create a decorative wall render with a course final surface is the ideal solution. It is a premixed render with coarse-grade particles, which only requires the addition of water and offers the following advantages:

  • It is completely watertight, according to DIN 18550.
  • There is no need for facade painting.
  • It allows excellent transpiration of the structure.
  • It is a manufactured mortar with stable properties.
  • It is suitable for external and internal use.
  • It does not crack like ordinary cement-lime renders.
  • It simplifies the job, since it only requires the addition of water.

It is suitable for making up white or colored, waterproof, render. It usually replaces the finishing layer of render.

III. APPLICATION

Spatterdash layer
Surfaces to be rendered must be free of any grease, dust, loose particles etc. and should be thoroughly dampened. After that, a  traditional spatterdash layer follows, which on difficult and smooth surfaces such as expanded or extruded polystyrene thermal insulating boards,should be reinforced by the addition of ADIPLAST polymer latex (cement : sand : ADIPLAST : water = 1 : 1 : 0,25 : 0,25), in order to improve the bonding of the spatterdash layer to the substrate. Instead of the traditional spatterdash layer, the premixed mortar MARMOCRET-BOND can be used.

Undercoat layer

  1. Once the spatterdash layer has hardened, a traditional undercoat layer is applied, in order to smooth out the surface and correct any construction imperfections in the wall. Instead of the traditional undercoat layer, the premixed mortar MARMOCRET-BASE can be used.
    Wherever the underlying surface consists of insulating layers, such as polystyrene, polyurethane, etc, on beams, supporting columns, walls and construction joints, etc, it is recommended that glass mesh reinforcement for render is applied during the application of the undercoat layer. This is to avoid cracking due to the particular thermal stresses evolved locally in the render on such surfaces and to the different coefficients of expansion and contraction of the individual layers.
    The glass mesh is positioned on the still fresh surface of the undercoat layer, using light pressure and it is extended to 10-15 cm beyond the area covered by the insulating boards.
  2. It is recommended that before MARMOCRET Decor is applied, especially where it is colored, the surface is primed with PL-PRIMER, which reduces its absorptivity, thus ensuring a uniform color over the entire surface.
    PL-PRIMER consumption: 40-100 g/m2, depending on the absorptivity of the surface.

Finishing layer – Application of MARMOCRET Decor

  1. MARMOCRET Decor is added to clean water under continuous stirring, until a mortar of the desired workability is obtained. The cement mixer used must be clean in order to avoid any alteration of the color of the render.
  2. MARMOCRET Decor is applied as usual with a float or trowel or by using a plastering machine.
  3. The render is then treated (pressed) by plastic or wooden float, in horizontal, vertical, or circular movements depending on the desirable appearance of the surface. Working time depends on substrate’s absorptivity and ambient temperature.

    MARMOCRET Decor consumption: Approx. 1,5 kg/m2/mm. Recommended thickness: 2,5-3,5 mm.

IV. REMARKS

  • The temperature during application of the material must be between +50C and +350C.
  • During summer months it is recommended that the rendered surface is kept damp after the application of the render, in order to be protected from dehydration due to high temperatures.
  • Consult the usage risk and safety advice written on the bag.