Floor Slab Settlement: What to Look For

Foundation settlement can cause immense damage to your home through cracks in foundation walls, floor slabs, dry wall and many other places. However, did you know that sometimes those cracks can be misleading? 

For example, a crack in your garage concrete floor slab might mean that your foundation is settling, but it actually could be much simpler than that. It is possible that while the foundation is stable and in place, the concrete floor slab alone is settling.

Slab settling is usually caused by one of the following reasons: 

- Drying and sinking of soil under the slab

Clay soil strikes again! Often, ventilating and air conditioning systems are installed beneath the floor slab. Over time, the ductwork can leak are causing the soil to dry out, becoming weak.  Gaps form under the floor slab and create a void that the slab begins to sink and crack into.  

This is usually caused by plumbing leaks. If the leak is severe enough it can wash out the soil under the floor slab, again creating a void that will cause the floor slab to crack and sink.

- Poor compaction of fill soil

During home construction layers of soil are moved around to spread out the grade level. Footings may be deepened to extend below weak fill soils. However, the slab remains on the fill soil. If the fill was poorly compacted, the soil compresses and settles, once again creating a void.  

Here are some signs of floor slab settlement to look for in your home: