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

# Types of shallow foundation

Building Technology · Chapter 2: Foundations

- Asked in: 2073 Bhadra
- Video: [Types of Foundation | Types of Footing | Types of Foundation in civil Engineering](https://www.youtube.com/watch?v=dO2lWAT-ltk) — Visual Civil
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/shallow-foundation-types
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-2

## Question

Explain different types of shallow foundation with neat sketches.

## Short answer

Shallow foundation depth is less than or equal to width. Types are wall or strip footing, isolated spread footing, combined footing, strap or cantilever footing, raft or mat foundation, grillage foundation, stepped footing on slopes, and inverted arch footing for soft soil.

## Answer

A **shallow foundation** is one whose depth is less than or equal to its width (generally under 3 m), and which transfers the load to the soil near the surface.

#### Types
1. **Wall (strip) footing**: Continuous footing under a load-bearing wall. Wider than the wall, with an offset, made of masonry or concrete.
2. **Isolated (spread) footing**: Square, rectangular or circular footing under a single column; the commonest type for RCC frames. May be flat, stepped, or sloped.
3. **Combined footing**: One footing carrying two or more columns; used when columns are close, or one is near the property line.
4. **Strap (cantilever) footing**: Two isolated footings joined by a strap beam; an edge column's eccentric load is balanced.
5. **Raft (mat) foundation**: A thick slab under the whole building. It is used for soil of low bearing capacity or where isolated footings cover more than about half the area.
6. **Grillage foundation**: Steel beams in layers (crossing) embedded in concrete, to spread heavy column loads over low-capacity soil, with shallow depth.
7. **Stepped foundation** on sloping ground for walls.
8. **Inverted arch** footing for soft soil between piers.

```text
 Wall footing         Isolated footing       Raft
   |wall|               | col |            ___________
  [_____]              [_______]          |___________|
```

## Check yourself

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

1. A shallow foundation is one whose depth is:
   A. Below the water table
   B. Always exactly 1 m
   C. Much greater than its width
   D. Less than or equal to its width, generally under 3 m
   Answer: D. Depth not more than width, transferring load to near-surface soil. (Key point: Shallow foundation definition)

2. What is the purpose of the strap beam in a strap footing?
   A. To support the roof
   B. To replace reinforcement
   C. To act as plinth DPC
   D. To balance the eccentric load of an edge column
   Answer: D. The strap joins two isolated footings, balancing the edge column's eccentric load. (Key point: Strap footing)

3. When is a raft foundation used?
   A. For rock at the surface
   B. For low bearing capacity soil or when footings cover over about half the area
   C. For single light columns on good soil
   D. Only for boundary walls
   Answer: B. A raft spreads load over the whole plan where soil is weak. (Key point: Raft use)

4. What is a grillage foundation?
   A. A hollow caisson
   B. Timber piles in clay
   C. A brick arch
   D. Steel beams in crossing layers embedded in concrete
   Answer: D. Grillage spreads heavy column loads over low-capacity soil at shallow depth. (Key point: Grillage)

## Related in Building Technology

- [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
- [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
- [Foundation settlement causes and underpinning](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asettlement-underpinning-067as) — Building Technology, chapter 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

## 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
- [Shallow and deep wells](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ashallow-deep-wells) — Water Supply Engineering, chapter 2, asked 4×
- [Classify shallow and deep foundations](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Aclassify-foundations-soil) — Foundation Engineering, chapter 1, asked 4×
- [When piles are preferred to shallow foundations](https://www.bctengineer.com/question.md?key=semester_5%2Ffoundation_engineering%3Apile-vs-shallow-conditions) — Foundation Engineering, chapter 8, asked 3×