Types of foundation and when to use them
Foundation of building or base of the building. Types of building, nature of soil and environmental conditions are the major reason for different types of foundation which can be used for your building.
1. Strip foundation– the most common.
This is a common type, it is mainly used where you have strong soil base and non-waterlogged areas. Most small buildings of just a floor are constructed with this type of foundation .
Depending on the structural engineers recommendation, the depth of your foundation could be from 600mm to 1200mm mostly for small scale foundations . When the soil is excavated, a level at which the concrete will settle evenly is established, then concrete is poured this may be from 150mm – 6” inches thick to 450mm – 18” inches thick depending also on building after that block is set round the trenches at the center of foundation ,the foundation usually follows the block lines. The blocks are then layed to damp proofing which sits on the top block of the foundation.
2. Pad foundation – obstacle in the way
Columns (pillars) are cast or shuttered from the foundation to carry a slab at the top of the ground. Most commonly used when you want to make use of the under of building i.e. car park or when the other space is not possible to have foundation. If you are planning to build a house across a stream. Then you may not need to dig foundation that will cut across the river but just by applying columns shutters at the river edge like a bridge, the columns are isolated and there foundations are referred to as pad.
3. Raft foundation – Probably most common in Ireland
This is where you have concrete spread around your building from the base of foundation all through to the floor or ground floor slab. It is mainly used in areas where the soil are sandy and loose, you may spend more on this than the other foundations x2 times. It is also recommended in waterlogged areas and buildings of less storeys in height.
It has a ground beam which shuts out from the foundation base and is also attached to the ground floor slab to form a network of concrete embedded round the building space (steel fixings). Usually from 24 inches 600mm to 48 inches 1200mm for low buildings.
4. Pile foundation – strongest type of foundation – expensive
The most expensive and the strongest type of foundation, this requires specialist engineering. Sections of the soil are bored deep down the earth and filled with concrete to be able to support loads the building load. Close to mountainous terrain or waterlogged area of high building may need Pile foundations.