Advantages and Disadvantages of Raft Foundation.

Advantages and Disadvantages of Raft Foundation:

Raft Foundation:

Mat or raft foundation is a large slab supporting a number of columns and walls under the entire structure or a large part of the structure to lower the contact pressure compared to spread footing.

When Mat/Raft Foundation is Recommended:

• It is recommended for the following purposes.
• Bearing capacity of soil is low,
• walls of the structure are so close that individual footings would overlap,
• it is used for large loads,
• individual footings would cover more than about half of the construction area.

Advantages of Raft Foundation:

• It has many advantages as well as disadvantages. The advantages of raft foundation are as follows,
• Raft or mat foundation is economic due to combination of foundation and floor slab.
• It requires little excavation.
• It can cope with mixed or poor ground condition.
• It reduces differential settlement.

Disadvantages of Raft Foundation:

• It has some disadvantages also. The disadvantages of raft foundation include the following.
• Mat foundation requires specific treatment for point loads.
• Edge erosion occurs if not treated properly.

Mat Foundation

Raft Foundation