---
title: "Cement-sand plastering and its types"
subject: "Building Technology"
chapter: 9
key: "semester_6/building_technology:plastering-process"
source: https://www.bctengineer.com/q/semester_6/building_technology/plastering-process
site: BCT Engineering
---

# Cement-sand plastering and its types

Building Technology · Chapter 9: Finishing works

- Asked in: 2078 Baisakh, 4 marks; 2065 Shrawan (old course), 4 marks; 2062 Poush (old course) (asked 3 times)
- Video: [Wall Plastering | Cement and Sand Wall Plastering | Building Construction | Easy Technique](https://www.youtube.com/watch?v=FVOXt4DeWkE) — DND Construction
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/plastering-process
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-9

## Question

Write down the cement sand plastering process for wall (plastering, its types and procedure of application).

## Short answer

Plastering applies cement‑sand mortar (1:4 external, 1:6 internal) for a smooth, durable wall finish. Types: single coat (12–15 mm), two‑coat (12 mm base + 6–8 mm finish), three‑coat (9–12 mm scratch +6–8 mm floating +2–3 mm finish). Procedure: prepare and wet surface, fix screeds, apply mortar in coats, level, cure 7 days.

## Answer

**Plastering** is the process of covering rough walls and ceilings with a coat of cement-sand mortar to give a smooth, even, durable and good-looking surface that also protects against weather.

#### Types of cement-sand plaster
- **Single coat plaster:** 12-15 mm in one coat, for ordinary work.
- **Two-coat plaster:** 12 mm base coat and 6-8 mm finishing coat; most common.
- **Three-coat plaster:** 9-12 mm scratch coat, 6-8 mm floating coat, 2-3 mm finishing coat; best quality.
- **Sand-faced, rough cast, pebble dash** and **stucco** are decorative finishes.

#### Proportion
Cement-sand 1:4 for external walls (1:6 for internal walls) and 1:3 for finishing coats and ceilings.

#### Procedure
1. **Preparation:** rake out the joints 10-12 mm deep; clean the surface of dust and oil; wet the wall.
2. **Fixing guides:** vertical lines are marked with plumb bob; patches of plaster or screed strips (gauges) are placed at 2 m c/c in level with the final plaster face.
3. **Mortar preparation:** cement and sand are mixed dry, and then water is added to get a workable mix.
4. **Applying the first coat (scratch coat):** mortar is thrown with a trowel and pressed firmly; surface is levelled with a flat wooden rule and scratched to form a key.
5. **Second coat:** after the first has set (1 day), apply 6-8 mm of floating coat, levelled.
6. **Finishing coat:** rubbed with a wooden float or trowel for a smooth or textured finish.
7. **Curing:** keep wet for at least 7 days.

```text
   wall|scratch coat|floating|finish
       | 12 mm      | 8 mm   | 3 mm
```

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is plastering?
   A. Fixing stone slabs
   B. Applying oil paint
   C. Covering rough walls and ceilings with mortar to give a smooth, durable surface
   D. Finishing of joints only
   Answer: C. Plaster gives a smooth, even, protective surface. (Key point: Plastering purpose)

2. Which coats make three-coat plaster, the best quality?
   A. Single, double, triple
   B. Priming, undercoat, finish
   C. Base, binder, thinner
   D. Scratch, floating, finishing
   Answer: D. Three-coat plaster has scratch (9-12 mm), floating (6-8 mm) and finishing (2-3 mm) coats. (Key point: Three-coat plaster)

3. Why is the first coat scratched?
   A. To form a key for the next coat
   B. To dry it faster
   C. To reduce thickness
   D. To make it smooth
   Answer: A. Scratching roughens the surface so the following coat bonds. (Key point: Scratching)

4. How long should cement plaster be cured?
   A. Only until surface dry
   B. At least 7 days, kept wet
   C. 1 day
   D. Not required
   Answer: B. Curing for at least 7 days prevents shrinkage cracks. (Key point: Curing)

## Related in Building Technology

- [Cement and sand for 100 m² plastering numerical](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aplaster-100m2-1to6) — Building Technology, chapter 3, asked 2×
- [Cement and sand for 200 m² plastering numerical](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aplaster-200m2-1to5) — Building Technology, chapter 3, asked 2×
- [Preparing cement mortar by manual process](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amortar-prep-manual) — Building Technology, chapter 3, asked 2×
- [Mortar properties; cement and sand for 10 cum](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amortar-quantity-10cum) — Building Technology, chapter 3

## Related in other subjects

- [Detailed specification of cement sand mortar 1:4](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-cs-mortar-1-4) — Construction Management, chapter 12, asked 2×
- [Detailed specification of cement sand mortar 1:6](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-cs-mortar-1-6) — Construction Management, chapter 12, asked 2×
- [Soundness test of cement and procedure](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acement-soundness-test-procedure) — Civil Engineering Materials, chapter 5
- [Active thrust, 6 m wall, sand over clay](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Atwo-layer-wall-6m-sand-clay) — Foundation Engineering, chapter 3, asked 4×