If you are planning a construction project or have enlisted the help of a foundation engineer, you may have come across several technical terms or descriptions which you would like to gain a better understanding of. Usually these terms are related to the type of foundation that is being used.
Shallow
Shallow foundations are quite common in residential building projects, as they don’t need to have a large bearing capacity (that is, the weight of the building is not significant enough to warrant deep foundation techniques).
Shallow foundations come in a few varieties – spread footing foundations (which use strips or pads of concrete) which are common in the UK, mat-slab foundations, and slab-on-grade foundations (which requires digging a mould which fits the floor plan of the building in the ground and pouring the concrete into the mould) which are popular in warmer climates.
Deep
Deep foundations are more often used in commercial, industrial or large-scale building projects, as with the increase in building size also comes the need for the soil to bear a larger load. Other reasons for using a deep foundation may include poor soil quality at a shallow level or an unusual site shape.
Some of the techniques used to create a deep foundation include piles driven into the ground at great depths (micropiles for underpinning, tripod piles, sheet piles and soldier piles are some of the varieties used), drilled or rotary-bored shafts, and several different types of reinforced or pre-tensioned concrete used in shafts.