Foundations can experience structural defects during the construction phase, and there are various reasons why this can occur. The problem areas, along with the impact on the foundation and the resulting structural defects, are outlined in the following paragraphs.
During construction, inadequate site preparation can be a primary cause of foundation defects. If the soil is not appropriately compacted and leveled, it can lead to a weak foundation. The impact on the foundation is that it may not be able to bear the weight of the structure, leading to sinking or settlement. The resulting structural defects can include cracks in the walls or floors.
Another cause of foundation defects is the use of substandard building materials during the construction process. This can lead to a weak foundation that cannot support the weight of the structure. The impact on the foundation can result in cracks and uneven settling, which can lead to structural defects such as bowing walls or sagging floors.
Furthermore, insufficient design and construction practices can also cause foundation defects. This can be due to inadequate soil investigation, inadequate foundation design, or incorrect installation of the foundation. The impact on the foundation can lead to foundation failure, which can result in severe structural defects such as structural collapse.
In summary, various factors can cause structural defects in foundations during construction, including inadequate site preparation, substandard building materials, and insufficient design and construction practices. The resulting impact on the foundation can lead to problems such as settling or sinking, which can cause cracks or bowing walls and sagging floors, and in severe cases, structural collapse.
| Problem Areas | Effect on foundation | Defects in structure |
| Insufficient depth of foundation (mostly in soft clayey soil) | Movement of foundation due to changes in water table seasonally, and movement due to trees and vegetation. | Cracks in walls at natural lines of structural weakness, i.e. windows, doors, junctions with extension and bays. |
| Insufficient width of foundation | Uneven settlement, building tilt, structural damage or collapse. | Cracks in walls, misaligned doors/windows, damage to structural elements, vulnerability to lateral/ uplift forces. |
| Soft-spots in sub-soil | Uneven settlement, structural damage or collapse due to low bearing capacity and high compressibility of soft spots in subsoil. | Cracks in walls, misaligned doors/windows, damage to structural elements, vulnerability to lateral loads and uplift forces.ion of foundation. |
| Insufficient steps in strip foundation on sloping ground. | Uneven settlement, structural damage or collapse due to differential settlement of the structure. | Cracks in walls, ceilings, and floors due to uneven settlement. |
| Trees and large shrubs close to building (mostly in case of soft shrinkable clayey soil) | Differential settlement and potential structural damage or collapse due to trees and large shrubs close to building, especially in soft shrinkable clayey soil. | Cracks in walls, misaligned doors/windows, damage to structural elements, and potential collapse of the building. |
| Clayey soil with high sulphate content. | Sulfate attack leading to weakening and potential collapse of the foundation in clayey soil with high sulfate content. | Cracking and spalling of concrete, weakening of mortar joints, loss of structural integrity, misalignment of doors/windows, and cracking in walls, ceilings, and floors. |
| Inadequate support to foundation from land-fill. | Excessive settlement of foundation which continues for a long time. | Cracking in walls, complete collapse of buildings. |
| Foundation near to drains where drains are running below foundation and / or drains lacking concrete cover. | Foundation is inadequately supported. | Cracking in walls occur above ground level and walls move out of plumb due to lateral movement of foundation. |