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

# Foundation requirements and shallow foundation types

Building Technology · Chapter 2: Foundations

- Asked in: 2075 Baisakh, 1+3+6 marks
- Video: [Types Of Foundation | Used in Building Construction | Deep and Shallow Foundation || By CivilGuruji](https://www.youtube.com/watch?v=0wYfbOZdzXs) — The Institute of Construction Managment 
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/foundation-define-requirements-shallow
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-2

## Question

Define foundation. What are the basic requirements of foundation? Explain different types of shallow foundation with necessary sketches.

## Short answer

Foundation is the lowest part of a structure, usually below ground, transmitting loads to soil. Requirements include adequate depth, safety against shear failure, limited uniform settlement, resistance to sliding and overturning, durability, earthquake resistance, economy, and a level stable base. Shallow types include strip, isolated, combined, strap, raft, and grillage footings.

## Answer

#### Foundation
A **foundation** is the lowest part of a structure, usually below ground, which transmits the load of the structure to the soil or rock.

#### Basic requirements of a foundation
1. **Adequate depth**, below the zone of frost, shrinkage, scour and the loose top soil.
2. **Safe against shear failure**: Soil pressure within the safe bearing capacity.
3. **Settlement within limits**, and uniform (no harmful differential settlement).
4. **Safe against sliding, overturning and uplift**.
5. **Durable**: Resistant to chemicals, sulphates and moisture.
6. **Resists earthquakes** and other special loads.
7. **Economical** and practical to construct.
8. **Level and stable base**: Bottom level on firm soil, with good drainage.

#### Types of shallow foundation
1. **Strip / wall footing**: Continuous below a load-bearing wall; it spreads the load by projecting offsets (in masonry, the width is about twice the wall width).
2. **Isolated (spread) footing**: A separate pad under each column, stepped or sloped, of reinforced concrete.
3. **Combined footing**: One footing for two or more columns, rectangular or trapezoidal, used when columns are close together or near the boundary.
4. **Strap footing**: Two footings joined by a strap beam to take an eccentric column load.
5. **Raft (mat) foundation**: A large slab covering the whole plan, for weak soil and heavy loads.
6. **Grillage footing**: Layers of steel beams in concrete, for heavy loads.

```text
  Strip:  |wall|      Isolated: |col|      Raft: ___________
          [____]                [___]            |_________|
  Combined: |c1|   |c2|          Strap: [F1]==beam==[F2]
            [_________]
```

## Check yourself

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

1. A foundation is:
   A. The roof of a building
   B. Only the plinth beam
   C. The finishing layer of plaster
   D. The lowest part of a structure that transmits load to soil or rock
   Answer: D. It transmits the structure's load to the soil or rock. (Key point: Definition)

2. Which requirement concerns settlement?
   A. It must be within limits and uniform
   B. It may be differential if small footings are used
   C. It is unimportant if soil is firm
   D. It must be zero
   Answer: A. Settlement must be limited and uniform to avoid harmful differential settlement. (Key point: Requirement: settlement)

3. When is a combined footing used?
   A. When columns are far apart
   B. For rocky soil only
   C. When columns are close or one is near the property line
   D. For load-bearing walls
   Answer: C. One footing carries two or more columns when separate footings would overlap or go over the boundary. (Key point: Combined footing)

4. Isolated footing is:
   A. A steel grid
   B. A separate pad under each column
   C. A slab under the whole building
   D. A continuous strip under walls
   Answer: B. It is a separate pad under a single column. (Key point: Isolated footing)

## Related in Building Technology

- [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
- [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 and its types](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Afoundation-types-sketches) — 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
- [Requirements of roof; coupled roof](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Aroof-requirements-coupled) — Building Technology, chapter 4

## Related in other subjects

- [Shallow versus deep foundation](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Ashallow-vs-deep-foundation) — Foundation Engineering, chapter 1
- [Basic requirements of a protection scheme](https://www.bctengineer.com/question.md?key=semester_6%2Fswitchgear_and_protection%3Abasic-requirements-protection-scheme) — Switchgear and Protection, chapter 1, asked 3×
- [Basic requirements of classification](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Abasic-requirements-classification) — Soil Mechanics, chapter 3, asked 2×
- [Basic requirements of linear programming](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Alinear-programming-requirements) — Project Engineering, chapter 3