Sagging of the structure is not just so
What causes foundations to sink?
Foundations settle for a number of reasons. All of them are related to changes in the properties of the soil base, which in turn causes movement of the soil on which the foundations are built.
Changes can be caused by:- Droughts or frosts that dry the ground and cause clay soils to shrink. In dry conditions, tree roots can suck residual moisture out of the ground and cause further settlement.- Major repairs or construction in the vicinity can change the condition of the soil, especially if excavation or piling work is carried out. Often, poorly executed excavations can allow “adjacent” soils to slide away, causing the supports to sink. Heavy traffic and machine vibrations can also move or displace soil layers.- Different foundation systems (e.g. in very old buildings or in houses with extensions or alterations) perform differently. Additions or extensions to a house will settle differently compared to the main structure. Most often, new foundations will settle in the first five years after construction.- Water that soaks into the ground changes the condition of the soil. This can be the result of leaks from broken pipes, poorly compacted foundation backfill or a sloping foundation (causing water to pool). In sandy soils, smaller particles are removed and larger particles settle. In clay soils, moisture saturation leads to weakening of the soil and the foundation sinks in the weak area.
Is there a solution?
