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How to apply render over existing render




Render coats are applied in successive layers

Render coats are applied in successive layers in decreasing thicknesses and strengths.

Topcoats therefore may be relatively weak. It is difficult to assess the strength of existing materials and their bond strength to previous layers.




Stresses from additional materials

Additional materials put increasing stresses on the bond interfaces of existing materials.

Dirty deposits

Dirty deposits accumulated over a period of time can form a weak intermediate layer that interferes with the development of the bond of newly applied render.



Poor key

Renders need a combination of mechanical key and suction to bond to the wall. Existing render surfaces even though unpainted or coated are usually “palin face” and seldom have sufficient key to hold a new render.


Choose your decorative solution and prepare the substrate accordingly



Solution 1

Substrate preparation

Providing the existing substrate is sound, well adhered over all its area, not substantially greater than 19 mm in thickness, stronger than the materials to be applied and not painted or coated in any way, power wash dirty areas.

Decorative solutions

Provide a key with all primers solutions or with premixed plasters and apply a finished texture with weber.pas and range.



Solution 2

Surface preparation

If the above criteria cannot be established, remove existing materials.

Decorative solutions

Provide a key with Premix.SRC-1 and apply a full specification thickness render with monocouche weber.pral F, weber.pral K, Palm.

Solution with the following weber products


weberpas PR 300

Acrylic water based primer

weberpas deco 330

Plastic decorative coating - roll finish

weberpas deco 340

Highly elastic facade coating

weberpas deco GM

Acrylic textured coating - coarse finish

weberpas PR SIL

A ready-to-use primer for the equalization and neutralization of the substrate

weberpas deco SIL

A ready-to-use high performance organo mineral based wet render


weberpremix SRC-1

Ready mixed spatterdash slurry coat for blocks

weberpral F

One-coat mineral decorative rendering mortar

weberpral K

Decorative single layer render

webercal palm

Decorative arabian render for internal and external use