How to Apply Cement Plaster on Walls

Published on 23rd March, 2017

how to apply cement plaster 1

CONMIX CP2 is a dry pre mix, cement plaster for internal and external use. This cement plaster is an ideal substrate for paint, wallpaper or decorative plasters. CP2 can be applied with a suitable plastering machine or by hand in accordance to BSEN 13914-1 & 2 onto prepared concrete surface, block work as well as most mineral backgrounds.

Application method

Before applying cement plaster, you have to prepare the background first:

  • The fair faced concrete background and the concrete blocks should be thoroughly cleaned using a stiff brush to remove any dust, loose particles, wood pieces, mould oil, etc.
  • The suction in the background of both fair faced concrete and block work should be neutralized by applying potable water.
  • Free water on the surface should be allowed to disperse before any further application.

If the surface is smooth or has low absorption rate, then mineral based bonding coat should be applied first to provide a mechanical key for subsequent layers.*

*CONMIX Bonding Rush Coat (BRC) mixed with appropriate amount of potable water (approximately 19% by weight i.e. 9.5 ltrs per 50 kg bag) using a mechanical mixer, should be spray applied on the prepared surface.

The applied BRC has to be water cured for a period of 2 days (3-4 times daily) before applying cement plaster (CP2).

In order to get uniformed thickness of plastering throughout the surface Fibre Glass Mesh / Expanded Metal Lath should be fixed at all junctions of dissimilar backgrounds or a groove has to be formed at the junction while the plaster is still soft.

Cement plaster has to be mixed with potable water only, in a clean plastic bucket or a clean non-corrosive, uncontaminated metal tub. To ensure a homogenous and uniform mix, an electric agitator must be used. The appropriate amount of water has to be added (approximately 17% by weight, i.e. 8.5 ltrs per 50 kg bag). Mix CP2 with water, turn the contents of the bag carefully and stir frequently. Once mixed, allow to stand for 5 minutes and mix again before applying. No further water should be added to the mix. Hard and set plaster should not be re-mixed or used. If a plaster spray machine used, the mixing ix carried out automatically.

Application of first coat: Mixed CP2 has to be applied to the prepared background, as a spatter dash/rush coat to a thickness of 6-8 mm. A rough texture has to be obtained to provide a mechanical key for the next coat. A minimum 48 hours have to elapse prior to the application of the second coat. Water curing is an absolute must during this period.

Application of second/final coat: With the second/final coat application, a total thickness of upto 20 mm can be built up and finished by felting or floating. If opted to use a plaster machine, the plaster is being applied continuously and the finishing should be done manually to its specified thickness to meet the necessary requirements (BSEN 13914-1 & BSEN 13914-2).

how to apply cement plaster 2

Special notes:

  • The finished plaster has to be water cured for a period of 2 days (3-4 times daily).
  • Before applying any kind of stucco finish, paint or wallpaper, the plaster has to be allowed to dry out completely, devoid of any moisture.
  • For application procedures in case of light weight blocks, concrete containing micro silica, GGBS, curing compound or any special additive/building material, kindly contact CONMIX Technical Service Department for assistance.