Volume = Area × Thickness × Coats
Weight = Volume × Density
Plaster is a building material used for coating walls, ceilings, and other surfaces to provide a smooth, durable, and aesthetically pleasing finish. It consists of a binder (such as cement, gypsum, or lime) mixed with sand and water. When applied wet, plaster hardens through a chemical process, creating a solid surface that can be painted or decorated.
Plastering serves multiple purposes: it protects walls from weather and moisture, improves thermal and acoustic insulation, and provides a base for decorative finishes. The type of plaster used depends on the application, with cement plaster being common for exterior walls and gypsum plaster preferred for interior surfaces due to its smooth finish.
Plastering is typically done in multiple coats, each serving a specific purpose. The number of coats depends on the surface condition, type of plaster, and desired finish quality.
First Coat (Scratch/Render Coat)
The base coat applied directly to the wall surface. It fills gaps, provides adhesion, and creates a rough surface for subsequent coats. Typically 10-15 mm thick.
Second Coat (Brown/Floating Coat)
Applied over the scratch coat to level the surface and achieve the desired thickness. This coat is floated to create an even surface. Usually 6-10 mm thick.
Third Coat (Finish/Set Coat)
The final thin coat that provides a smooth, paintable surface. Applied at 2-3 mm thickness and troweled to achieve the desired finish texture.
- Account for openings: Subtract the area of doors, windows, and other openings from the total wall area.
- Surface condition: Rough or uneven surfaces require more plaster than smooth surfaces.
- Wastage factor: Always add 5-10% for spillage, waste, and uneven application.
- Mixing ratio: For cement plaster, typical ratios are 1:4 to 1:6 (cement:sand) depending on application.
- Curing: Proper curing is essential for plaster strength; keep the surface moist for at least 7 days.
Disclaimer
Results are estimates. Actual plaster requirements may vary due to surface texture, workmanship, and site conditions. Always consult with a professional contractor for accurate material quantities and consider purchasing slightly more than calculated to account for unforeseen variations.