How deep should a raft foundation be?
Raft foundations (sometimes referred to as raft footings or mat foundations) are formed by reinforced concrete slabs of uniform thickness (typically 150 mm to 300 mm) that cover a wide area, often the entire footprint of a building.
Where raft foundation is provided?
Civil engineering and building works
Raft foundations are essentially large plan area foundations built either solidly or in cellular form. They may be employed for lightly loaded structures on soft natural ground or on other ground where weak zones exist.
What is the difference between strip and raft foundations?
Strip foundation is used to support a line of loads such as load-bearing walls. … Raft foundation consists of a concrete slab which extends over the entire loaded area so that loads from entire structure are spread over a large area leading to a reduction of the stress of foundation soils is reduced.
Is a raft foundation expensive?
Raft foundations are relatively inexpensive and fast to put down, when compared with other types of foundation. Ground excavations are less onerous than for trench excavations, for example, and the foundation and floor slab can often be combined, giving significant savings on materials and time.
Which soil is suitable for raft foundation?
Usually clay has a higher moisture content and when the moisture content becomes stable upto certain depth it becomes suitable for the substructure. Raft foundation is preferred when the clayey soil is compact and hard. Even strap foundation can also be used. Soft clayey sand is prone to expansion and shrinkage.