What does a sinking floor mean?

Sinking concrete floors are an indication of building subsidence (when the ground sinks due to movement of underground material).

A building can sink at various points or the collapse can be spread across the entire footprint of the foundation, depending on where the affected ground is and how large an area it is. This can be very serious, and if left untended is likely to worsen, creating further building subsidence and other consequent damage.

The problem

The problem – a 50mm drop in the slab at a busy seaport

The solution

The solution – the slab is re-levelled and the container forklifts can run on it just 30 minutes later

Sinking floors in civil and Infrastructure

In the infrastructure sector, subsidence can fast cause havoc. Sinking structures, floors, and ground create numerous problems, and are likely to become hazardous if not resolved promptly and correctly. Mainmark’s methods have delivered results to thousands of projects worldwide.

We have successfully raised, re-levelled and re-supported sunken roads and highways, bridge approach slabs, bridge abutments, culvert areas, concrete slabs, airports, seaports, railways, parking areas, and many other civil works. The level-correction solutions we provide are sought for many reasons; not least of which are the cost effective and time efficient processes we use. Bringing the structure or approach slab back to level means everything is back on an even keel, optimising business output.

Most importantly, structural damage is resolved, and the future of the structure is sound. In fact, our methods actually improve the structure’s bearing capacity. Mainmark methods are suitable for any building or structure, of any size. We also re-level parking areas, loading docks, hardstand areas, driveways, and roads.

What causes subsidence?

There are many different causes of subsidence and various contributing factors. All involve some sort of change in the ground, which, in turn, generates movement of the soil. For example, droughts dry the ground, resulting in the soil (especially clay) contracting. Seismic activity shakes the ground, often resulting in liquefaction which ‘squeezes’ liquid up from the ground. Excavation and construction, even heavy traffic and machinery vibration, can move, displace and alter the condition of the ground.

As well, different types of ground are more affected by different conditions. For example; clay is particularly prone to contracting in drought conditions, gravel and stony grounds can be more affected by nearby excavation, and excess water has a softening effect on dirt. Subsidence can happen over large areas of land or in a small targeted area. It can occur over a lengthy period of time, or can be an immediate reaction to nearby activity or natural events. When ground has been affected, building subsidence is common. Foundations or footings are no longer ably supported, sinking due to weak ground.

Likely causes:

Water flooding the ground

Drought drying out soil

Washaways from broken pipes (such as water, sewer, stormwater drainage)

Poorly compacted fill

Liquid, gas or mineral resources being removed from the ground


Earthquake and seismic activity

Tree roots can suck moisture from the ground

Vibrations caused by heavy road traffic or by machinery

Absence of an organised footing system – in very old buildings or in buildings with additions or alterations

Nearby excavation

Heavy loading

Deterioration of retaining walls

How to fix sinking floors?

The only way to fix sinking concrete floors is to raise foundation, re-level and re-support the building. Mainmark specialises in concrete levelling. Level correction not only re-levels a building, but also strengthens any weak ground under and around the perimeter of the foundations, ensuring a stable base and helping to avoid any recurring sinking issues. Traditional level correction or “underpinning” methods involve excavating or digging up parts of the foundation, pouring in concrete, waiting for it to set and then jacking up the building off the concrete blocks. This method can be:

  • time consuming (often requiring weeks or months)
  • messy
  • usually means you’ll have to vacate part or all of the building while tradespeople work

Mainmark methods are much friendlier, both to the building and to those that occupy it. Our non-invasive concrete re-levelling techniques are cost and time efficient. Various product warranties and Building Code requirements apply (please contact us to see which apply in your region or country).

Key benefits of Mainmark’s level correction methods include:

There is minimum disruption to the site, no excavation and no mess

There is little, if any, downtime to the site: in many cases, it can still operate (this is case-dependent, site requirements may be such that this is not possible)

Projects are completed in a significantly faster timeframe than traditional methods

Non-invasive techniques mean further damage to the site, and the landscaping around it, is absolutely minimal. We don’t tear up areas or excavate ground, creating costly and time-wasting messes

Trip hazards are eliminated. Vehicles and machinery can run smoothly almost immediately

Re-levelling is completed in a fraction of the time of traditional methods. There’s no cutting out of old approach slabs and no waiting days for new slabs to cure

There are usually substantial cost savings, in comparison to traditional methods

Weight is no problem. In fact the greater the weight on the ground, the more it can be compacted. Huge ground support can be created, especially when the area is loaded with weight

There’s minimal interruption to traffic flow or activities to busy facilities, such as roads or airports

The methods we use strengthen weak ground, so the site becomes level and more stable.

Mainmark level correction methods used in the Infrastructure sector: