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Weber Saint-Gobain - Official website of the company

Direct-applied rendering to surfaces with a poor key

Renders are not adhesives and require a combination of suction (drawing of the most liquid elements into the substrate) and mechanical key (texture or roughness) to bond to its substrate.


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1. Brickwork

Brickwork with the mortar joints raked back will provide sufficient mechanical key for rendering.  However, if the joints are flush, a key has to be provided by other means.

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2. Blockwork

As the density of blockwork increases the finished surfaces often have much smoother faces.

Raking the joints on blockwork will not provide sufficient key for rendering as the frequency of joints are considerably less than in brickwork.

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3. Smooth concrete

Smooth concrete may offer the worst of all conditions for rendering, with the possibility of residual traces of release agents and both poor key and low suction.


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Apply weberend aid and suitable render

Preparatory key coats are very heavily polymer modified to 'stick' to poor key substrates and are finished with a pronounced texture to hold the new render.

Solution with the following Weber products

Solution 1

weberend aid

Preparatory key coat for rendering

weberpral M

One-coat, through-coloured, water resistant monocouche render

weberend OCR

Pre-blended single coat application renders

webersil TF

Silicone-based, through-coloured, decorative finish

weberplast TF

Acrylic-based, composite, decorative finish

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