The presence of sinking and uneven floors is something that many people are not aware of. Occupying a property for an extended period of time may result in progressive changes being so slight that they are not detected, yet newcomers to the building may notice a slope straight away. Tell tale signs can be the pet toys always accumulating along one wall of the room or your eggs always slide to the back of the fry pan.
Fortunately in instances where the construction has suspended timber floors, most floor sagging can be corrected by adjusting the supporting stumps or piers. However, where there are masonry walls, either internally or around the perimeter, the continuous strip footing will need to be corrected. In the case of concrete slabs, this would also be addressed by treating the foundation elements together with the panels, across the entire affected area.
Not all floor settlement represents foundation movement. Infill slabs are a flooring system that is independent of the perimeter walls and so are capable of moving in isolation. Therefore the mechanism of failure may be unrelated to external factors that typically influence perimeter foundations. Commonly, deterioration of the underlying ground below the slab, due to poor preparation or plumbing failures, leads to unacceptable level variations. As with structural slabs, treatment involves supporting the portion of the slab that is out of tolerance and requires correction.
Changes in moisture levels, especially in clay-rich soils, can cause the ground to swell when wet and shrink when dry. This fluctuation leads to uneven foundation support, causing subsidence.
Trees and large shrubs can absorb significant amounts of water from the soil, leading to shrinkage beneath foundations. Additionally, roots growing under the house can physically move the soil, destabilizing the foundation.
Persistent water leaks from broken pipes or poor drainage can wash away or soften the soil under a foundation, leading to subsidence as the ground loses its ability to support the structure.
Adding extensions or conservatories without properly assessing the additional load can exceed the soil's bearing capacity under a home, causing the foundation to sink. This is a common issue when expanding residential properties without thorough ground assessment.
Excavation and construction work in close proximity to residential properties can disturb the soil's stability, leading to subsidence. The vibrations from heavy machinery and the removal of support from adjacent land can have a significant impact.
Leaking pipes, especially those running beneath a house, can erode or soften the soil foundation over time. In residential properties, unnoticed leaks are a frequent cause of sudden or gradual subsidence, as they change the soil's consistency and capacity to bear weight.