What is a raft foundation?

Explanation:

Raft Foundation:

A raft foundation is generally a thick concrete slab resting on a large area of soil reinforced with steel rods and is used to support columns or walls and transfer loads from the structure to the soil.

Raft foundation may be used under the following conditions:

• The soil has a low bearing capacity.
• The load of the structure has to be distributed over a large area
• Individual or any other foundation area would approximately cover 50% of the total ground area beneath the structure.
• To resist uplift pressure
• The columns or walls are placed so closely that the individual footings would overlap.
• Stress on soil needs to be reduced.
• There is a possibility of differential settlement in case individual footing is used.
• When soil strata are unpredictable and contain pockets of compressible soil.
• The basement is to be constructed.
• Any other type of footing cannot be used advantageously.