BeginnerTopic 35 of 112Civil & Structural
Shallow foundations
Footings and rafts spread load near the surface.
In depth
Isolated and combined footings, strip footings, raft (mat) foundations spread loads near the surface. Depth below frost and shrink-swell zones; check bearing, settlement and sliding. Rafts reduce differential settlement on weak soils.
Key points
- Minimum 0.5–1 m depth
- Reinforced concrete design as inverted beam
- Differential settlement limits
ExampleHouses typically use strip footings; tall buildings may use a thick raft.
What is Shallow foundations?
Footings and rafts spread load near the surface.
Why is it important to understand shallow foundations?
Shallow foundations spread loads near the surface, and they are the cheapest option when the soil near the surface is strong enough.
When is a shallow foundation suitable?
When the soil at a shallow depth has enough strength and low compressibility to carry the load with acceptable settlement.
What is a raft foundation?
A continuous slab covering the whole footprint of a building, which spreads load over a large area and reduces differential settlement.
How is Shallow foundations used in practice?
Typical applications include supporting a house with strip footings on firm ground, using a raft under a tank that spreads load over the whole base and placing pad footings under a steel frame.
What should I learn before Shallow foundations?
Study "Bearing capacity" first (topic 34 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
What are the key points of Shallow foundations?
Minimum 0.5–1 m depth. Reinforced concrete design as inverted beam. Differential settlement limits.
Can you give an example of Shallow foundations?
Houses typically use strip footings; tall buildings may use a thick raft.
What comes after Shallow foundations?
The next topic is "Deep foundations", which builds directly on this one.
How difficult is Shallow foundations?
It is classed as Beginner in Civil & Structural (topic 35 of 112). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.