HOW TO APPLY CEMENT PLASTER ON WALL SURFACE?

Cement plastering is commonly used as the ideal coating for the exterior and interior surface of the wall. Cement plaster is generally applied in single coat or double coat. Double coat plaster is applied where thickness of plaster more than 15 mm is required or when it is required to have a very fine finish. The process of applying a double coat cement plaster to the wall surface consists of the following 5 steps.

  • Step 1 – Preparing the Surface for Plastering
  • Step 2 – Groundwork for the Plaster
  • Step-3 – Applying the first coat (or undercoat or rendering coat)
  • Step-4 – Applying a Second Coat (or Finishing Coat or Fine Coat)

Step-by-Step Guide to Cement Plastering

Step-1 (Preparing the Surface for Plastering)

  1. Keep all mortar joints in the wall rough, giving a good bonding to hold the plaster.
  2. Clean all joints and surfaces of the wall with a wire brush, leaving no oil or grease on the surface of the wall.
  3. If the surface is smooth or the wall to be plastered is old, rake the mortar joint to a depth of at least 12 mm to give better bonding to the plaster.
  4. If the projection on the wall surface is more than 12 mm, cut it off, so as to obtain an even surface of the wall. This will reduce the consumption of plaster.
  5. If there are any holes or holes on the surface, fill it in advance with the appropriate material.
  6. To plaster, rough up the entire wall.
  7. Wash the mortar joints and the entire wall to plaster, and keep it wet for at least 6 hours before applying the cement plaster.

Step-2 (The Ground Work for the Plaster)

  1. To obtain a uniform thickness of plaster over the entire surface of the wall, first fix dots on the wall. One point means a patch of plaster of size 15 mm * 15 mm and whose thickness is about 10 mm.
  2. Dots on the wall are placed first horizontally and then vertically at a distance of about 2 meters covering the entire wall surface.
  3. Check the verticality of the dots, one on top of the other by means of a plumb-bob.
  4. After fixing the points, vertical strips of plaster, known as screw, are formed between the dots. These screws serve as a gauge to keep the thickness of the plaster being applied.
point and screw
point and screw

Step-3 (Applying First Coat or Under Coat or Rendering Coat)

  1. The thickness of first coat plaster is normally 12 mm in case of brick masonry and varies from 9 to 15 mm in case of concrete masonry.
  2. The ratio of cement and sand for first coat plaster varies from 1:3 to 1:6.
  3. Apply the first coat of plaster between the spaces formed by the screed on the surface of the wall. This is done by means of a trowel.
  4. Level the surface through the flat wooden floats and the straight edges of the wood.
  5. After leveling, leave the first coat to set, but not to dry, and then rough it up with a scraper to key in the second coat of plaster.

Step-4 (Applying Second Coat or Finishing Coat or Fine Coat)

  1. The thickness of the second coat or finishing coat can vary between 2 to 3 mm.
  2. The ratio of cement and sand for second coat plaster varies from 1:4 to 1:6.
  3. Before applying the second coat, moisten the first coat evenly.
  4. Apply the finishing coat with wooden floats to an even surface and give it a finishing touch using a steel trowel.
  5. As far as possible, the finishing coat should be applied starting from top to bottom and completed in one operation to eliminate join marks.

After completion of plastering it is kept wet by sprinkling water for at least 7 days to develop strength and hardness.

Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.