The foundation is a critical element in construction, serving as the stable base for an entire structure. It plays a crucial role in distributing the building’s load evenly to the ground, effectively anchoring the construction. Out of the many types of foundations, shallow foundations are the most commonly used.
What is a Shallow Foundation?
A shallow foundation is one that transfers the building weight to the ground closer to the surface- The depth of the shallow foundation is lesser than or equivalent to the width of the foundation.
This type of foundation is usually built for lighter structures such as homes, small offices or boundary walls. Shallow foundation is best suited for soil that has enough capacity to bear the load.
Types of Shallow Foundation
There are various types of shallow foundation, each suited for different types of constructions and soils. Here are some of the most commonly used types-
1. Spread Footing or Isolated Footing
An isolated footing is a common type of shallow foundation designed to support a single column. These footings are typically square or rectangular and are spread out over a dug-out area to provide a stable base. They are best suited for light structures due to their ease of construction and cost-effectiveness.
2. Combined Footing
In the Combined footing foundation, the footings are built to support more than one column. This is because where the columns are being built close to each other and their footings may overlap- this makes building separate footings impractical. This type of foundation is also suited for construction where the two columns carry different loads – distributing the varied loads uniformly and preventing the issue of differential settlement.
3. Strip Footing
A strip footing foundation is built as a continuous running platform of concrete beneath the walls that carry the load of the structure, improving the strength of the building. The strip must be long enough to rest firmly on the ground. The strength of the soil determines the width of the strip foundation. For weaker soils, the strip should be built wider to distribute the building weight across the foundation area.
Strip foundation is best suited for residential structures of medium height. In such buildings the concrete strip runs beneath the entire length of the wall, providing a stable support for the building.
This type of foundation is sometimes used to support columns that are very closely built. In such cases, it proves to be more efficient and cost effective, as one strip can support a row of columns rather than building isolated footings that overlap.
4. Mat or Raft Foundation
A Mat foundation is the type where one slab of concrete is built over the entire construction ground to provide one solid base to carry the weight of the structure over a large area. This mat or raft foundation distributes the weight of the building evenly and prevents over loading the soil. Mat foundations are best suited for areas where the soil is weak and can support multiple walls and columns at once.
Raft foundation is best suited for heavy structures that need a stronger foundation.
Shallow Foundation Depth
The depth of shallow foundations typically ranges from 1 meter to 3 meters (approx 10 feet), depending on various factors such as
- Amount of load- The more the weight of the structure, the more the depth of the foundation.
- Type of construction– For lightweight structures such as boundary walls, the foundation can be closer to the surface, whereas for heavy structures like residential buildings, the foundation could be 1 to 1.5 meters. .
- Soil type – Stronger soils carry their load-bearing capacity, and hence don’t require the foundation to be dug very deep, but weak soils require a stronger and deeper foundation base.
Shallow Foundation Diagram
Refer to the diagram below for a more in depth understanding of shallow foundations.
Shallow foundations owe their popularity to the fact that they are easy and quicker to construct. Understanding the various types of shallow foundation and the factors that affect the decision in picking the right one is important to maintain your project’s structural integrity, strength and longevity in the future. Choosing the right foundation is the first step towards building a strong structure that is long-lasting and safe.
FAQs
1. What is a shallow foundation, really?
Picture this: you’re building a single-storey house in Jaipur or a small shop in Nashik. You don’t need to go too deep into the earth. That’s exactly where a shallow foundation fits in. It sits close to the surface — usually within 3 metres — and spreads the load sideways. It’s fast, practical, and cost-effective when the soil near the top is strong enough to support the structure. We see this on hundreds of sites across India — from village schools to two-floor townhouses.
2. Why do engineers prefer shallow foundations in most residential projects?
Because it just makes sense when the ground is good. You dig less, save labour, and finish faster. In cities like Bhopal or Nagpur, where the soil isn’t too soft or shaky, shallow foundations are the go-to. They work well when the building load is light to moderate and there’s no risk of soil collapse or groundwater trouble.
3. What are the different types of shallow foundation we actually use on site?
There’s theory — and then there’s what really happens on site. Here’s a quick breakdown of types of shallow foundation commonly used in India:
- Isolated footing — single columns, single footings. Classic choice for pillar-based homes.
- Combined footing — when two columns are close and their footings would overlap, we combine.
- Strip footing — supports long load-bearing walls, seen in compound walls or old-style houses.
- Raft (Mat) foundation — spreads across the whole building area, useful in weak soils.
- Wall footing — a straight, continuous base under partition or boundary walls.
Each type of shallow foundation comes with its own fit depending on soil, budget, and structural load.
4. Can a raft foundation be called a shallow foundation too?
Yes — and it often surprises people. Raft foundations, even though they cover a large area, are still shallow foundations because they stay close to the surface. They’re especially handy when you’re building on soft soil and want to avoid uneven settlement. Think of a bungalow on marshy land in Bengal — raft footing helps balance the load like a well-spread dosa batter on a tawa.
5. Is soil testing really necessary for shallow foundations?
Always. Just because it’s shallow doesn’t mean it’s simple. You’d be shocked how often we see cracks or sinking plinths because the soil wasn’t tested properly. In some areas, like around the coastal belt or parts of UP, even shallow footings can fail if the groundwater table plays games during monsoon. It’s better to spend on a soil test now than redo a foundation later.
Picture this: you’re building a single-storey house in Jaipur or a small shop in Nashik. You don’t need to go too deep into the earth. That’s exactly where a shallow foundation fits in. It sits close to the surface — usually within 3 metres — and spreads the load sideways. It’s fast, practical, and cost-effective when the soil near the top is strong enough to support the structure. We see this on hundreds of sites across India — from village schools to two-floor townhouses.
Because it just makes sense when the ground is good. You dig less, save labour, and finish faster. In cities like Bhopal or Nagpur, where the soil isn’t too soft or shaky, shallow foundations are the go-to. They work well when the building load is light to moderate and there’s no risk of soil collapse or groundwater trouble.
There’s theory — and then there’s what really happens on site. Here’s a quick breakdown of types of shallow foundation commonly used in India:
Isolated footing — single columns, single footings. Classic choice for pillar-based homes.
Combined footing — when two columns are close and their footings would overlap, we combine.
Strip footing — supports long load-bearing walls, seen in compound walls or old-style houses.
Raft (Mat) foundation — spreads across the whole building area, useful in weak soils.
Wall footing — a straight, continuous base under partition or boundary walls.
Each type of shallow foundation comes with its own fit depending on soil, budget, and structural loa
Yes — and it often surprises people. Raft foundations, even though they cover a large area, are still shallow foundations because they stay close to the surface. They’re especially handy when you’re building on soft soil and want to avoid uneven settlement. Think of a bungalow on marshy land in Bengal — raft footing helps balance the load like a well-spread dosa batter on a tawa.
Always. Just because it’s shallow doesn’t mean it’s simple. You’d be shocked how often we see cracks or sinking plinths because the soil wasn’t tested properly. In some areas, like around the coastal belt or parts of UP, even shallow footings can fail if the groundwater table plays games during monsoon. It’s better to spend on a soil test now than redo a foundation later.
