---
title: "Materials: 150 m³ brick 1:4, 120 m² plaster"
subject: "Estimating and Costing"
chapter: 4
key: "semester_7/estimating_and_costing:materials-brick-150m3-plaster-120m2"
source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/materials-brick-150m3-plaster-120m2
site: BCT Engineering
---

# Materials: 150 m³ brick 1:4, 120 m² plaster

Estimating and Costing · Chapter 4: Analysis of Rates

- Asked in: 2067 Poush (old course)
- Video: [How to Calculate Quantity of Cement & Sand For Plaster](https://www.youtube.com/watch?v=pk8pAG5VxDg) — YAHYA SIR - PRODUCTIVE TALK
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/materials-brick-150m3-plaster-120m2
- Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-4

## Question

Calculate the quantities of materials required for the following works: i) 150 m³ of brick work in (1:4) cement mortar in super structure ii) 120 m² of 20 mm thick cement sand plaster (1:4).

## Short answer

For 150 m3 brickwork in 1:4 mortar, assuming 230x110x55 mm bricks with 10 mm joints and dry volume 1.27 times wet: bricks 80,129, cement 281.6 bags, sand 39.12 m3. For 120 m2 20 mm plaster: cement 17.6 bags, sand 2.44 m3. Totals: cement 299.2 bags, sand 41.56 m3.

## Answer

Assumptions: dry volume 1.27 × wet for mortar; 1 m³ cement = 28.8 bags; brick 230 × 110 × 55 mm with 10 mm joints (not given); no wastage.

#### (i) 150 m³ of brickwork in 1:4 mortar

- Brick with mortar $= 0.240 \times 0.120 \times 0.065 = 1872.0\times 10^{-6}$ m³; bricks per m³ $= 1/(1872.0\times10^{-6}) = 534.19$
- Bricks for 150.00 m³ $= 534.19 \times 150.00 = 80,128$ nos (say 80,129)
- Volume of bricks only $= 0.230\times0.110\times0.055 = 1391.5\times10^{-6}$ m³ each; wet mortar per m³ $= 1 - 534.19\times1391.5\times10^{-6} = 0.2567$ m³
- Wet mortar for 150.00 m³ $= 38.502$ m³; dry $= 1.27\times38.502 = 48.897$ m³
- Cement $= 1/5\times48.897 = 9.779$ m³ $= 281.6$ bags
- Sand $= 4/5\times48.897 = 39.118$ m³

#### (ii) 120 m² of 20 mm plaster (1:4)

- Wet mortar $= 120.0 \times 0.0200 = 2.4000$ m³; dry volume $= 1.27 \times 2.4000 = 3.0480$ m³
- Cement $= 1/5 \times 3.0480 = 0.6096$ m³ $= 17.56$ bags
- Sand $= 4/5 \times 3.0480 = 2.4384$ m³

**Answer: (i) bricks 80,129, cement 281.6 bags, sand 39.12 m³. (ii) cement 17.6 bags, sand 2.44 m³. Total cement = 299.2 bags; total sand = 41.56 m³.**

## Check yourself

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

1. How are the bricks for 150 m3 found?
   A. 150 divided by the brick-only volume
   B. Bricks per m3 (1 / volume of brick with mortar = 534.19) x 150
   C. 534.19 x 1.27 x 150
   D. Wall area divided by brick face area only
   Answer: B. Using the mortar-inclusive size, 534.19 x 150 = about 80,129 bricks. (Key point: Bricks for 150 m3)

2. What gives the dry mortar for the 150 m3 of 1:4 brickwork?
   A. 150 x 0.2567 x 1.54
   B. 1.27 x 150 with no deduction for bricks
   C. Wet mortar 0.2567 m3 per m3 x 150 = 38.50 m3, times 1.27 = 48.90 m3 dry
   D. 150 x 0.02 = 3 m3
   Answer: C. Mortar is the non-brick space; the 1.27 factor converts wet to dry. (Key point: Mortar in brickwork)

3. How are cement and sand for 120 m2 of 20 mm plaster (1:4) obtained?
   A. Wet mortar = 120 x 0.20 m3; cement 1/4
   B. Dry = 1.54 x 2.4; cement 1/4 and sand 3/4
   C. Wet mortar = 120 x 0.02; cement 1/4 and sand 4/4 of wet volume
   D. Wet mortar = 120 x 0.02 = 2.4 m3; dry = 1.27 x 2.4 = 3.048 m3; cement 1/5, sand 4/5
   Answer: D. Sum of ratio is 5, giving cement 0.6096 m3 = 17.56 bags and sand 2.44 m3. (Key point: Plaster mortar)

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