---
title: "Preliminary estimate: polytechnic, 800 students"
subject: "Estimating and Costing"
chapter: 3
key: "semester_7/estimating_and_costing:prelim-est-polytechnic-800"
source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/prelim-est-polytechnic-800
site: BCT Engineering
---

# Preliminary estimate: polytechnic, 800 students

Estimating and Costing · Chapter 3: Types of Estimate

- Asked in: 2080 Bhadra, 6 marks
- Video: [Preliminary Estimate Example ( Using PLINTH AREA) PART-2](https://www.youtube.com/watch?v=vJ_aQ24pz74) — Civil Friend
- 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-polytechnic-800
- Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-3

## Question

Prepare a preliminary estimate of a poly-technique building for student number 800 in order to assess the amount for building based on the following particulars.
Carpet area required per student = 1.2 sq.m.
Area of corridors, verandah etc. = 20% of plinth area
Plinth area rate = Rs. 3500 per square meters.
Area of walls = 15% of plinth area.
Cost of water supply work = 5% of building cost.
Cost of sanitary = 7% of building cost.
Cost of electrification = 12% of building cost.
Cost of approach road and boundary walls = 3% of building cost.
Contingencies and work charge establishments shall be 5% and 2.5% of the total cost respectively.

## Short answer

Carpet area 960 m² gives plinth area 1,476.92 m². Civil cost at Rs3,500/m² = Rs5,169,230.77. Including 5% water,7% sanitary,12% electrification,3% roads/walls,5% contingency,2.5% work-charged: total Rs7,057,292.31.

## Answer

#### Plinth area
Carpet area = 800 x 1.2 = 960 m².
$$
\text{Plinth area} = \frac{960}{1 - 0.20 - 0.15} = \frac{960}{0.65} = 1,476.92\ \text{m}^2
$$

#### Estimate
Extras are percentages of the building cost; contingency and work-charged establishment are on the total cost (building plus extras).

| Item | Basis | Amount (Rs) |
|---|---|---|
| Building cost (plinth area x rate) | 1,476.92 m² x 3,500 | 5,169,230.77 |
| Water supply work | 5% of civil cost | 258,461.54 |
| Sanitary work | 7% of civil cost | 361,846.15 |
| Electrification | 12% of civil cost | 620,307.69 |
| Approach road and boundary walls | 3% of civil cost | 155,076.92 |
| **Total building cost** | | **6,564,923.08** |
| Contingencies | 5% of 6,564,923 | 328,246.15 |
| Work-charged establishment | 2.5% of 6,564,923 | 164,123.08 |
| **Total estimated cost** | | **7,057,292.31** |

**Answer: Total estimated cost = Rs 7,057,292.31.**

## Check yourself

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

1. Carpet 960 m2, corridors 20%, walls 15%. Plinth area:
   A. 1,476.92 m2
   B. 1,248 m2
   C. 960 m2
   D. 1,100 m2
   Answer: A. 960/0.65 = 1,476.92. (Key point: Plinth area)

2. Extras 5% + 7% + 12% + 3% of building cost add up to:
   A. 22%
   B. 27%
   C. 12%
   D. 17%
   Answer: B. Total building cost = 1.27 x 5,169,230.77 = 6,564,923. (Key point: Extras)

3. On what are contingency 5% and work charge 2.5% charged?
   A. The plinth area
   B. Only the civil cost
   C. The total cost (building plus extras)
   D. The carpet area
   Answer: C. Rs 6,564,923 x 7.5% is added. (Key point: Contingency base)

4. The total estimated cost is:
   A. Rs 6,564,923.08
   B. Rs 7,200,000
   C. Rs 5,169,230.77
   D. Rs 7,057,292.31
   Answer: D. 6,564,923.08 x 1.075 = 7,057,292.31. (Key point: Total)

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