Quick answer: A footing is the widened base of a foundation that spreads a building’s load safely onto the soil. Footings fall into two groups: shallow foundations — wall/strip, spread/isolated, combined, strap and raft footings — used when firm soil is near the surface; and deep foundations — mainly pile foundations — used when the surface soil is weak or the structure is heavy. The right type depends on soil bearing capacity, building load, water table and site conditions.
Footings are the first structural element built on site, and everything above depends on them. Get them wrong and you get settlement, cracked walls, or worse. This guide explains every common type of footing, organised the way engineers actually think about them — shallow versus deep — with a comparison table and how to choose the right one.
What is a footing?
A footing is the lowest part of a foundation, usually reinforced concrete, that sits directly on the soil and transfers the load of walls or columns into the ground over a wider area. By spreading the load, it keeps soil pressure within safe limits and prevents the building from settling unevenly. (For the full definition, importance and construction process, see our guide on what footings are in house construction.)
Types of footings at a glance
| Footing type | Category | Supports | Best for |
|---|---|---|---|
| Wall / strip footing | Shallow | Load-bearing walls | Homes with masonry / load-bearing walls |
| Spread / isolated footing | Shallow | A single column | RCC framed homes on firm soil |
| Combined footing | Shallow | Two or more close columns | Columns near a boundary or too close for separate footings |
| Strap (cantilever) footing | Shallow | Two columns via a strap beam | A column near the plot edge tied to an interior column |
| Raft / mat foundation | Shallow | The whole building | Weak/soft soil, or heavy closely-spaced columns |
| Pile foundation | Deep | Columns/whole structure | Weak surface soil, high water table, high-rise loads |
Shallow foundations
Shallow foundations sit relatively close to the surface and are the norm for most homes and low-rise buildings where firm soil is available.
Wall / strip footing
A continuous strip of concrete running under a load-bearing wall, spreading the wall’s load along its length. It can be a simple uniform strip or a stepped strip where the base is wider than the wall. Best for homes where walls (not columns) carry the load.
Spread / isolated footing
An individual pad — usually square or rectangular — under a single column. The most common footing in RCC framed homes. It spreads one column’s load onto firm soil and is economical where columns are reasonably spaced and the soil has good bearing capacity.
Combined footing
A single footing supporting two or more columns. Used when columns are too close for separate footings, or when a column sits near the plot boundary and can’t have a centred footing of its own. It shares the load and helps avoid uneven settlement.
Strap (cantilever) footing
Two separate footings joined by a rigid strap beam. Typically used when an exterior column sits right at the property line: its footing is tied back to an interior column’s footing so the load stays balanced.
Raft / mat foundation
A single thick slab of reinforced concrete covering the entire building footprint, so the whole structure rests on one continuous base. Used on weak or soft soil, or where columns are so heavy and close that individual footings would nearly touch. It spreads the load over the largest possible area.
Deep foundations
When the soil near the surface can’t carry the load — soft or filled ground, a high water table, or a heavy structure — the load has to be transferred deeper.
Pile foundation
Long columns of concrete (or steel) driven or bored deep into the ground until they reach a firm stratum or gain enough friction along their length. Piles are standard for high-rise buildings, structures on weak soil, and sites with a high water table. They prevent the excessive settlement that shallow footings would suffer in poor soil.
(For very heavy loads, piers or caissons — large-diameter deep supports — are used similarly.)
Special footing shapes
These describe the shape of a footing rather than a separate category:
- Stepped footing: the base is stepped outward in stages (widest at the bottom). This spreads the load efficiently while saving concrete compared with one thick block. It is about load distribution and economy not corrosion.
- Sloped / tapered footing: the top surface slopes down from the column to the edge (a trapezoidal section), using less concrete than a uniform-thickness footing while still carrying the load.
How to choose the right footing
Footing selection is an engineering decision based on:
- Soil bearing capacity: firm soil allows shallow footings; weak or filled soil pushes you toward raft or piles. A soil test comes first.
- Building load: heavier or taller structures need larger or deeper foundations.
- Water table: a high water table often rules out simple shallow footings.
- Site and space: columns near boundaries or close together call for combined or strap footings.
Always have a structural engineer design the footing from a soil test and the building’s load — this is not a place to guess.
Build on a foundation that lasts
Footings are poured in structural-grade concrete — typically M25 or higher — with correct reinforcement. At Walls & Dreams, every foundation is designed from a soil test and executed to spec. See our construction projects or talk to our team about your build.
Frequently asked questions
What is the most common type of footing for a house?
For RCC framed homes, the isolated (spread) footing under each column is most common. For homes with load-bearing walls, continuous wall/strip footings are used.
What is the difference between shallow and deep foundations?
Shallow foundations (strip, isolated, combined, strap, raft) rest near the surface on firm soil. Deep foundations (piles) transfer the load to a firmer layer far below, used when surface soil is weak or the structure is heavy.
Which footing is best for weak or soft soil?
A raft (mat) foundation spreads the load across the whole footprint, and pile foundations carry it down to firmer soil. The choice depends on how weak the soil is and the building’s load — decided from a soil test.
What is the difference between isolated and combined footing?
An isolated footing supports one column; a combined footing supports two or more columns on a single base, used when columns are close together or near a boundary.
What is a raft foundation?
A single continuous reinforced-concrete slab under the entire building that acts as one large footing — used on weak soil or under heavy, closely-spaced columns.
Is a footing the same as a foundation?
No. The footing is the widened base at the very bottom that meets the soil; the foundation is the broader system (footings plus foundation walls/columns) that carries the building’s load to the ground.
