---
title: "Need for soil test / soil exploration"
subject: "Building Technology"
chapter: 2
key: "semester_6/building_technology:soil-test-need"
source: https://www.bctengineer.com/q/semester_6/building_technology/soil-test-need
site: BCT Engineering
---

# Need for soil test / soil exploration

Building Technology · Chapter 2: Foundations

- Asked in: 2081 Chaitra, 2 marks; 2079 Asoj, 2 marks (asked 2 times)
- Video: [Essential Soil Tests for Building Construction – Everything You Need to Know!](https://www.youtube.com/watch?v=_IYe6O-_BaQ) — Urban Builders Guide
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/soil-test-need
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-2

## Question

Why is it necessary to carry out soil test (soil exploration) for the foundation design?

## Short answer

Soil testing determines layer profiles, bearing capacity, settlement potential, and the groundwater level, preventing failure. It identifies problem soils and guides the choice between shallow and deep foundations, ensuring safe and economical design.

## Answer

Soil exploration (soil test) is necessary for foundation design because:
1. It finds the **type, thickness and sequence of soil layers** and the depth of rock.
2. It gives the **bearing capacity** of soil, which decides the size and type of foundation.
3. It allows the probable **settlement** (total and differential) to be estimated, so the design is safe.
4. It locates the **water table**, which affects excavation, bearing capacity and dewatering.
5. It finds **problem soils** such as black cotton soil, peat, fill or liquefiable sand.
6. It helps to choose between **shallow and deep foundations**, or ground improvement.
7. It gives information for the **economy and safety** of the building, preventing failure and damage, and avoiding over-design.

## Check yourself

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

1. Why is bearing capacity from soil tests needed?
   A. It sets the paint colour
   B. It fixes the roof slope
   C. It gives the wall thickness only
   D. It decides the size and type of foundation
   Answer: D. Bearing capacity decides foundation size and type. (Key point: Bearing capacity)

2. What does locating the water table affect?
   A. Only brick quality
   B. Only roof design
   C. Excavation, bearing capacity and dewatering
   D. Nothing in foundation design
   Answer: C. Water table affects excavation, bearing capacity and dewatering. (Key point: Water table)

3. How does soil exploration help economy?
   A. It increases the foundation size always
   B. It removes the need for design
   C. It raises cost with no benefit
   D. Avoids failure and over-design
   Answer: D. Knowing soil properties prevents failure and over-design. (Key point: Economy)

## Related in Building Technology

- [Soil exploration and improving bearing capacity](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asoil-exploration-improving-bc-nepal) — Building Technology, chapter 2
- [Soil exploration, safe bearing capacity, improvement](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aexploration-bc-065s) — Building Technology, chapter 2
- [Sub-soil exploration, improving bearing capacity](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asubsoil-exploration-improve) — Building Technology, chapter 2
- [Define soil exploration](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Adefine-soil-exploration) — Building Technology, chapter 2
- [Foundation settlement, effects, black cotton soil](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asettlement-black-cotton-062ba) — Building Technology, chapter 2
- [Factors affecting foundation design, improving bearing capacity](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afactors-design-improve-bc) — Building Technology, chapter 2

## Related in other subjects

- [Purposes of foundation soil improvement](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Asoil-improvement-purposes) — Foundation Engineering, chapter 10
- [UCS test soil type and parameters](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aunconfined-compression-soil-type-mohr) — Soil Mechanics, chapter 10
- [CBR test on subgrade soil](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Acbr-test) — Transportation Engineering I, chapter 6
- [Major criteria in foundation design](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Afoundation-design-criteria) — Foundation Engineering, chapter 1, asked 4×