The biggest reason your walls are bowing or leaning is because of excessive lateral pressure outside the wall. All that pressure can be too much for your basement, seawall, or retaining wall to handle. Here’s why that happens.
Expansive soil – Clay-rich soils are prone to absorbing a lot of water. The more water they absorb, the more the dirt expands. The more the dirt expands, the more pressure is placed against your wall. Expansive soils also shrink when they dry, removing support from your wall. The constant cycle of swell and shrink places repetitive stress on your foundation. The American Society of Civil Engineers estimates that 1/4 of all homes in the United States have some damage caused by expansive soils.
Hydrostatic pressure – Your foundation wall acts as a barrier or dam against the soil outside your home. When soil starts to accumulate too much water and has nowhere to go, it starts to push against your wall. Home’s built in areas with a high water table are most prone to hydrostatic pressure. Water can then use bowing walls to leak into your basement. Read more about foundation leak repair solutions.
Frost heave – When water freezes, its volume increases by about 9%. In colder climates, saturated soil can freeze, increasing the weight of the dirt. The increase in weight will push against your wall. When the dirt finally unfreezes, the change in weight and pressure allows the wall to fall back to its original position. This back and forth motion causes severe stress on your foundation.