It is normal for the foundation of a house to settle (sink to a lower level) as time goes on. Even with new houses, some form of settlement can be expected as the weight of the building compacts the soil it is built on, squeezing out any excess water.

Over longer periods of time, foundation settling can become more pronounced. This is typically caused by problem soil, rotten wood, piers sinking into the earth or pilings that weren’t driven deep enough when the house was first built years before.

New or old, when a house starts to settle unevenly, the floors also begin to sag. Other signs of more severe forms of foundation sinking include doors and windows that don’t open or close properly, interior and exterior wall cracks, tile cracks, floor bumps and squeaky floors.

Settling also causes walls to turn or rotate outwards as the structure goes down. Wall cracks caused by rotation tend to be tapered - larger at the top and smaller at the bottom of the wall. When the walls rotate, they also pull at the ceiling joists and rafters. When the rafters are pulled, the roof is pulled as well, which can cause roof leaks and sagging.

Foundation settlement can be repaired by a process called floor leveling. Leveling a floor is as much art as it is a science. The basic process requires lifting up the foundation and rotating the walls back into their proper place.

Before lifting the foundation, wood rot needs to be removed. The structure is then shored – supported in some way to prevent collapse. Beams are then inserted under the house with jacks. The jacks must then be raised evenly, after which new piers are added to stabilize the adjustment and provide permanent support.

If floor leveling isn’t done correctly, it can cause more severe damage to the house. For example, if the structure is raised too high, walls can pop out and windows can break. If too much pressure is used or not spread out evenly, the jacks and beams can punch holes in the floor.

House leveling is specialized work best done by an experienced professional. A house leveling expert will be able to determine what caused the sinking and he will know the best way to repair it. This is one job you shouldn’t try to do yourself. Any mistakes can cause the entire structure to fall down.