Sinking Floors

A sinking concrete floor can be a sign of the subsidence of a building or a confined floor sinking into its footprint.

In most cases a sinking floor is isolated to the concrete slab set within a building’s structural walls. If this is the case, Geobear can stabilise and in most cases lift the floor back up. You’ll see a dropping floor as there will be gaps around the skirting or floor tiles may crack.

Where supporting walls are built off a slab, you may see diagonal cracks in walls in the area where there is most subsidence.

What causes my floor to sink?

Subsidence is often the root cause and can be the result of many differing factors. Each factor involves a change that has taken place within the soil beneath, which then allows a movement to take place in the ground. For example, when there is an extensive period without rainfall, the soil contracts. This is particularly prevalent in clay soils.

Alternatively, excess water such as a leaking drain, may cause a washout of the made ground or soil beneath your concrete floor slab, this will ultimately lead to downward movement of the entire floor.

Likely causes:

  • Flooding
  • An extensive period without rain allows the soil to become too dry- contraction
  • Excessive water due to broken pipes (such as water, sewage, storm water drainage)
  • Fillings that have been compacted poorly
  • The removal of resources (liquid, gas or mineral) from the ground
  • Moisture can be removed from the ground by tree roots
  • Vibrations caused by heavy road traffic or machines
  • Heavy loading


How to stop your floor sinking

To correct a sinking concrete floor, we first need to diagnose and prevent the cause. That could be invasive tree roots, leaking drains or natural compaction of soil.  Once we understand the problem we can provide a permanent solution and in most cases lift the floor again.

We use our original Uretek technology to inject an expansive material into the ground to fill voids in the soil and stabilise the ground. Once the voids are filled in the soil, the material will force the concrete slab up, where in most cases we can re-level.

The alternative is traditional underpinning or mini piles which involve the excavation of parts of the foundation, this is a very long, inconvenient approach that should only be considered a last resort. Where Geobear takes one day, the alternative takes weeks.