---
title: "Foundation and its types"
subject: "Building Technology"
chapter: 2
key: "semester_6/building_technology:foundation-types-sketches"
source: https://www.bctengineer.com/q/semester_6/building_technology/foundation-types-sketches
site: BCT Engineering
---

# Foundation and its types

Building Technology · Chapter 2: Foundations

- Asked in: 2069 Bhadra, 8 marks
- Video: [types of foundation in civil engineering || types of foundation in building construction 🔥🔥](https://www.youtube.com/watch?v=yxIe71VkewQ) — Civil Notebook
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/foundation-types-sketches
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-2

## Question

Define foundation. Describe types of foundation with necessary sketches.

## Short answer

Foundation is the part below ground transferring superstructure loads safely to soil without shear failure or harmful settlement. Types include shallow: strip, isolated, combined, strap, raft, grillage; deep: pile, pier, well or caisson. Choice depends on soil bearing capacity, load, water table, settlement, and cost.

## Answer

**Foundation** is the part of a structure, usually below ground level, which transfers the loads of the superstructure to the soil safely without shear failure or harmful settlement.

#### Types of foundation
**A. Shallow foundations** (depth $\le$ width)
1. **Strip / wall footing**: Continuous strip under walls.
2. **Isolated (spread) footing**: Under a single column; flat, stepped or sloped.
3. **Combined footing**: Carries two or more columns.
4. **Strap (cantilever) footing**: Two footings joined with a strap beam.
5. **Raft (mat) foundation**: A slab under the whole building for weak soil.
6. **Grillage footing**: Steel beams in concrete layers.

**B. Deep foundations**
1. **Pile foundation**: End-bearing or friction piles of timber, concrete or steel.
2. **Pier foundation**: Large shaft of masonry or concrete.
3. **Well (caisson) foundation**: Hollow sunk wells for bridges.

```text
 Strip      Isolated     Raft         Pile
 |wall|      | col |   |c| |c| |c|   | col |
 [____]      [_____]   [__________]  [cap ]
                                      | | |
```

Choice depends on soil bearing capacity, load, water table, settlement, and cost. Shallow footing is used for firm soil; raft for low capacity; piles for deep firm layers.

## Check yourself

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

1. A foundation transfers superstructure loads to the soil:
   A. Without regard to bearing capacity
   B. Safely without shear failure or harmful settlement
   C. Only to the plinth
   D. By tension only
   Answer: B. Its function is safe load transfer with no shear failure or harmful settlement. (Key point: Foundation definition)

2. Which pair is correctly classified?
   A. Raft - deep; pile - shallow
   B. Raft - shallow; pile - deep
   C. Grillage - deep; well - shallow
   D. Strip - deep; pier - shallow
   Answer: B. Raft is shallow; pile, pier and well are deep. (Key point: Classification)

3. A raft foundation is mainly suited to:
   A. Very hard rock
   B. Single columns
   C. Boundary walls
   D. Weak soil under the whole building
   Answer: D. A raft slab spreads load over weak soil. (Key point: Raft use)

4. Piles are chosen when:
   A. A firm layer lies at depth
   B. Loads are very small
   C. Soil is firm at the surface
   D. There is no water table
   Answer: A. Piles reach deep firm layers. (Key point: Choice of type)

## Related in Building Technology

- [Why joints are necessary; expansion joint](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Ajoints-why-expansion) — Building Technology, chapter 10, asked 2×
- [Foundation requirements and shallow foundation types](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afoundation-define-requirements-shallow) — Building Technology, chapter 2
- [Functions of foundation, deep foundation types](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afoundation-functions-deep) — Building Technology, chapter 2
- [Foundation settlement causes and underpinning](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asettlement-underpinning-067as) — Building Technology, chapter 2
- [Types of shallow foundation](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Ashallow-foundation-types) — Building Technology, chapter 2
- [Deep foundation types and use of shallow foundations](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Adeep-shallow-types-079a) — Building Technology, chapter 2

## Related in other subjects

- [Compensated foundation and types of mat](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Acompensated-foundation-mat-types) — Foundation Engineering, chapter 7, asked 7×