Raft

Definition

A raft is a footing or foundation, usually a large, thick concrete mat that supports a building or structure.

Purpose

The purpose of a raft foundation is to spread the load of the building over a large area, providing stability on soft or loose soil, and preventing differential settlement.

Examples of Use

• Raft foundations are used in high-rise buildings to provide a stable base on challenging soil conditions.
• Industrial structures with heavy loads often use raft foundations to distribute the weight evenly.
• Residential buildings in areas with expansive soils may use raft foundations to prevent movement and damage.

Related Terms

• Mat Foundation: Another term for a raft foundation, indicating a large concrete slab supporting multiple columns.
• Pile Foundation: Deep foundations using long, slender columns driven into the ground to support structures.
• Footing: The part of a foundation that transfers loads from the building to the ground.

Notes

Raft foundations are particularly effective in areas where soil conditions are unpredictable or where loads are unevenly distributed.