---
title: "Preliminary estimate: five-storey office, 2500 m²"
subject: "Estimating and Costing"
chapter: 3
key: "semester_7/estimating_and_costing:prelim-est-five-storey-2500"
source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/prelim-est-five-storey-2500
site: BCT Engineering
---

# Preliminary estimate: five-storey office, 2500 m²

Estimating and Costing · Chapter 3: Types of Estimate

- Asked in: 2076 Asoj, 5 marks
- Video: [Preliminary estimate of five storied building](https://www.youtube.com/watch?v=mU_jONCEkBs) — Civil Giri
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/prelim-est-five-storey-2500
- Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-3

## Question

Prepare a preliminary estimate of a five storied office building having total carpet area of 2500 m² for obtaining the administrative approval of the government, given the following data:
(i) 30% of the built-up area will be taken up by corridors, verandah, staircase, lift etc and 10% of the built up area will be occupied by walls.
(ii) Prevailing plinth area rate Rs. 25000.00 per m².
(iii) Provide 20% extra cost for water supply and sanitary fittings, electrical works, contingencies and other services.

## Short answer

Plinth area = 4,166.67 m². Building cost at Rs25,000/m² = Rs104,166,666.67. Adding 20% for water, sanitary, electrical, contingencies and other services gives total Rs125,000,000.

## Answer

#### Plinth area
$$
\text{Plinth area} = \frac{2500}{1 - 0.30 - 0.10} = 4,166.67\ \text{m}^2
$$
(total of five floors; 833.33 m² per floor.)

#### Estimate
| Item | Basis | Amount (Rs) |
|---|---|---|
| Cost of building | 4,166.67 x 25,000 | 104,166,666.67 |
| Water supply, sanitary, electrical, contingency and other services | 20% of building cost | 20,833,333.33 |
| **Total** | | **125,000,000.00** |

**Answer: Total estimated cost = Rs 125,000,000.00 (Rs 12.5 crore).**

## Check yourself

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

1. Circulation 30%, walls 10%. Plinth area of the five floors:
   A. 2,500 m2
   B. 3,125 m2
   C. 1,750 m2
   D. 4,166.67 m2
   Answer: D. 2500/0.6 = 4,166.67. (Key point: Plinth area)

2. The building cost at Rs 25,000/m2 is:
   A. Rs 104,166,666.67
   B. Rs 62,500,000
   C. Rs 125,000,000
   D. Rs 20,833,333
   Answer: A. 4,166.67 x 25,000. (Key point: Building cost)

3. How is the 20% used?
   A. Applied on the carpet area
   B. One lump percentage of building cost covering water supply, electrical, contingency and other services
   C. Each service gets 20%
   D. Deducted from the building cost
   Answer: B. Total = 1.20 x 104,166,666.67 = Rs 125,000,000. (Key point: Extra 20%)

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