Plastering a wall means you want to give the wall a smooth and level finish with the use of a cementitious compound. Plaster is a protective or decorative coating for walls and ceiling.If a wall is constructed of sandcrete blocks then chances are high that it will be plastered to give a very smooth aesthetic finish.
Difference between plastering and rendering
“plaster” usually means a material used for the interiors of buildings, while “render” commonly refers to applications on external walls.
Types of plaster
- Gypsum plaster: Also called plaster of Paris, it is calcium sulphate hemihydrate a white cementing material composed of gypsum, retarded and hardeners. It is applied to the wall in a plastic state. It thereafter hardens by the chemical combination of the gypsum and water. Gypsum plaster are usually supplied in bags.
- Cement plaster: This is a mixture of portland cement and sand. It is applied in the plastic state after mixing with water. It thereafter hardens after the chemical combination of the cement and water. Ready mix cement plaster is supplied in bags.
This is the most commonly used plaster material because it is cheaper and more versatile than the gypsum plaster.
Ready mix cement plaster is available but expensive. It is more economical to mix on site, cement, sand and water and use it to plaster / design walls.
Materials needed for cement plaster
- Cement: usually supplied in 50kg bags.
- Plaster sand. A type of fine sand that bonds very well with cement in the presence of water.
- Clean water of drinking quality.
Mixing of cement and sand for plaster works
Thorough mixing of cement and sand is first done in the dry state. After that water is added and mixed to a workable plastic state before application. For plastering works, the cement sand ratio is usually 1:4 or 1:6. Ratio 1:6 being the more commonly adopted ratio.
To calculate the amount of cement and sand need for wall plastering, read the article below by clicking on the link.