Drying & Shrinking Soils
Foundation soils usually shrink and dry due to Drought: During prolonged dry periods, the soils around your home may begin to dry out. As clay soils dry out, they will shrink considerably. When this happens under a foundation, it’s the same as the soil settling. Your foundation will settle downwards as it does so, possibly leading to structural damage. Maturing Trees: A mature tree’s root system can be up to twice the size of its visible part. If the trees extend over your home, that’s a good sign that they’re under your house as well. As they draw up hundreds of gallons of water each day, the soils will shrink significantly.
Wetting & Softening Of Soil
Foundation soils usually wet and soften in three scenarios:
Heavy Rain & Flooding: When clay soils contact water, they hold on to it and become very soft. This soft soils is not good load-bearing soil, and heavy objects will sink down into it.
Poor Drainage: If water is allowed to “pond” next to the home due to poor soil grading, clogged gutters, or some other factor, the soils will absorb the water. If the soils around the home are clay, then they will soften, and the home may sink.
Plumbing Leaks & Broken Water Lines: Plumbing leaks under or around a home can also saturate the soils around a home, and potentially weaken their load-bearing capacity.
Poorly Compacted Fill Soil
To make a level surface where your foundation can be built, builders will sometimes bring in loose soil from another location, using it to fill in hollow or depressed areas. This recently excavated “fill” soil is fluffed and will be much looser and lighter than the dense, hard-packed virgin soils already present. To compensate, the builder will need to compact the fill soil thoroughly before placing a foundation on top. If this compaction is not done or is improperly done, then the weight of your home may cause the soil to compress, leading to foundation settlement issues.