An undercoat in any part shall have a thickness of not less than 8 mm, nor more than 12 mm.
If greater thickness is required to build up an even surface, additional undercoats must be used.
For colored cement renderings, the undercoat must be admixed with waterproofing compound to provide a waterproofing base.
Final or Finishing Coat
The thickness of the final or finishing coat will be governed to some extent by the texture required.
Normally 3 to 8 mm is considered satisfactory.
Some of the fine-textured machine applied finishes may be as thin as 3 mm.
Single Coat Rendering
In the case of dense background, such as of cement concrete, or where surface of the background is very even (as for example, walls built with hollow concrete blocks) or buildings subjected to moderate, or light exposure conditions, wood-float; rendering can be applied in one coat.
It must not be thicker than 18 mm or thinner than 6 mm in any portion.
Extreme care needs to be taken in preparing the surface of the background to ensure adequate bond between the rendering and the background.