Foundation types and construction methods

Foundation types and construction methods

Foundation Types

Strip Foundations

  • Strip foundations are the most common type, supporting a line of loads such as a wall.
  • They are relatively shallow and used where ground conditions are good and the building is light-structured.
  • Often used in typical home constructions.

Pad Foundations

  • Pad foundations support an individual point load such as a structural column.
  • Suitable where the ground is firm and stable.
  • These are a form of isolated or spread footing foundations.

Raft Foundations

  • Raft foundations spread the load of the building over the entire ground floor area of the building.
  • Good for poor soil conditions where strip or pad foundations would not be suitable.
  • Typically used for buildings on compressible ground such as clay or silt.

Pile Foundations

  • Pile foundations are deep foundations, used where the ground conditions require a greater depth to achieve a stable foundation.
  • Utilised when the topsoil is weak and heavy loads are expected.
  • Transfers load to a deeper, more stable stratum.

Construction Methods

Strip and Pad Foundations Construction

  • The ground is dug to the required depth and a layer of concrete is poured to create a level base.
  • Added reinforced steel can provide additional stability and strength.
  • The size and shape of the foundation depend on the type of the load it will carry.

Raft Foundations Construction

  • The entire area is dug out and levelled, then a reinforced concrete slab is laid.
  • The slab acts as the whole footing for the entire building providing an even distribution of loads.
  • Reinforcement is often provided in the upper and lower zones of the slab to resist bending caused by the imposed loads.

Pile Foundations Construction

  • Piles are driven or bored deep into the earth using a pile driver.
  • After installation, the pile heads are connected with a pile cap that transfers the load from the building to the piles.
  • There are different types of piles including end-bearing piles (load directly transferred to firm soil), friction piles (load transferred to soil along the surface of the pile), and combination piles (use both methods of load transfer).