Going beyond the actual integrity of the construction, the most important factor in the stability of a house foundation is the soil and earth around it.
For example, many soils are rich in clay which can contract and expand depending on the amount of moisture in it. When clay is saturated with water it expands and consequently weakens the soil making it more ‘elastic’. Backfilled soil is another type of soils that can cause movement in the foundations of a house. If not compacted in the right way, it too can be weak and allow the foundation of a house to move.
Another main cause of structural movement in a building is the presence of large foliage in the surrounding area. A mature tree, for example, can take in as much as 30 gallons of water in a solitary day. This drains the moisture of the soil nearby and can lead to reduced strength in the neighboring dry soil.
Conversely, bad drainage in the surrounding area of a house can have the opposite effect. As moisture builds up in the soil it becomes heavier and therefore put extra pressure on the walls. Then when the soils dries out it pulls away again.
These forces push and pull at the basement walls and over time caused them to change their shape. This is where the bowing occurs. An early sign of bowing walls are cracks in the surface. If you do see these it’s worth getting someone out to look at the overall structure. This is not a do it yourself job and you should contact a foundation repair contractor to come out and give you a free quote and assess the extent of the damage.