Repairing renders

RELATED MATERIALS

UNICRET Mortar for rendering and masonry

UNICRET-FAST Fast-setting, white repairing mortar

ADIPLAST Polymer latex for multiple improvements of mortars

FIBERGLASS MESH Fiberglass mesh for render reinforcing

 

I. NATURE OF THE PROBLEM – REQUIREMENTS

The preparation of a traditional render requires the supply and storage of significant quantities of different materials on site (cement, lime, sand) for a considerable length of time. The resultant mortars are not of the same quality, since the mixing proportions cannot be stable and the quality of the ingredients varies with the supplied batches.

Further difficulties arise in carrying out the various tasks, due to lack of space. Moreover, keeping the site clean is also a problem. In addition, loss of quantities is usually inevitable, because of the storage of the materials in heaps.

II. SOLUTION

UNICRET cement-lime mortar enables rapid and easy preparation of mortars for plastering and building, which are characterized by:

  • Stable quality.
  • Easy use – Simplified application.
  • Excellent workability.
  • Excellent bonding to the substrate.

It is ideal for repairing render and generally for all kinds of repair works.


III. APPLICATION

Spatterdash
The substrate must be free of all dust, grease, loose particles etc.

A spatterdash of UNICRET is applied. In order to improve bonding to the surface, it is recommended that the spatterdash is reinforced with ADIPLAST polymer latex, which should be added to the mixing water in a ratio of ADIPLAST : water = 1 : 3.

Application of UNICRET

  1. Once the spatterdash layer has hardened, UNICRET is applied in a maximum thickness of 2 cm per layer. The number of layers needed depends on the desired surface smoothness and substrate’s imperfections. UNICRET is applied in the same way as ordinary render with float or trowel.
  2. Once the final coat has cured sufficiently, it should be treated with a sponge-faced float (slight rubbing). The length of time required for the surface to become suitable for rubbing depends on the absorptivity of the substrate, the ambient temperature and the workability of the mixture.
    Consumption: approx. 15,5 kg/m2/cm of layer thickness.
    Where the substrate consists of thermoinsulating layers (e.g. polystyrene, polyurethane etc.), e.g. on beams, columns, concrete walls, bind/beams etc., it is recommended that UNICRET is reinforced with fibreglass mesh for renders. This is to avoid cracking due to the thermal burden that render has to undergo locally on these surfaces undergoes and the different coefficients of expansion and contraction between the individual layers. The fiberglass mesh should be positioned using light pressure during the application of the final coat of UNICRET, it is extended 10-15 cm beyond the area covered by the insulating material, and it should be completely covered by UNICRET.

IV. REMARKS

  • UNICRET must be applied at temperatures between +50C and +350C.
  • During summer months it is recommended that UNICRET is dampened after being applied, in order to be protected from dehydration due to high temperatures.
  • In case fast work is required and the surface to be repaired is small, UNICRET-FAST fast setting mortar can be used instead of UNICRET.
  • Consult the usage risks and safety advice written on the bag.