Sinking Floors

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Sinking Floors

The last thing any homeowner wants to deal with is unwanted structural issues. Unfortunately, they are more common than you may realise. In particular, sinking floors are more common than most people may realise, and one of the most common symptoms is concrete sinking within a structure or home. It becomes noticeable when a dishing effect occurs when the concrete floor starts to sink towards the middle, but the edges remain level. Another common occurrence is when the centre remains level while the concrete at the wall or footing starts to sink. When a floor has masonry piers supports or is of timber construction, either can lead to sinking. Relevelling the floor or foundations is the only way to remedy the issue.

What Is A Sinking Floor?

A sinking floor is evidence of building subsidence, which means the ground is sinking due to underground material movement. As the building can sink at different points, a collapse can spread across the entire slab or foundation. The seriousness of the situation depends on the ground that is affected and how large an area has been affected.

Why is your floor sinking?

There are a variety of causes for sinking floors; they all involve a change in the ground which agitates the soil. During a drought, the ground contracts. Seismic activity can squeeze liquid to the surface from the ground. Construction, heavy traffic, excavation, and machine vibrations can also change the ground’s condition. Different conditions impact different grounds. Clay is more prone to react to seasonal changes, while stone and gravel are more likely to be impacted by construction nearby. When the ground is affected, sinking floors are a common outcome because footings and foundations no longer need structural support.

  • Flooding on or near the grounds
  • Dried out soil caused by droughts
  • Poorly compacted fill
  • Termites or other pests.
  • Nearby excavation
  • Resources being removed from the nearby ground, whether it’s minerals, gas, or liquids
  • Seismic activity
  • Tree roots drying out the ground, as roots can absorb all of the moisture in an area
  • Heavy loading
  • Nearby vibrations from machinery, construction or heavy traffic
  • Wash away from stormwater drainage or water and sewage pipes
  • Retaining wall deterioration
  • A lack of organised footing systems, which is common in older buildings or buildings that had been altered or had additions

There is only one solution to sinking floors: raise the foundation, re-level the area, and re-support the building. However, there is more than one way to achieve this outcome. Level correction strengthens weak ground and re-levels the building. The traditional method requires excavation, concrete pouring, and jacking the building, which can be a messy, time-consuming, and expensive project. This would only be necessary for the most severe of circumstances. R&R has a much more friendly, cost-effective and non-invasive solution to repair your sinking floors.

How do I know my floor is sinking?

One of the most common signs your floor is sinking is when your house is cracking – on the walls, ceilings or floors. Another key tell-tale are concrete cracks on the slab itself. 

Cracks in concrete slabs may not always be visible on the top surface as it may be covered by carpet or the concrete surface itself is under compression which disguises the distress; however, the cracks may exist on the underside of the sinking slab where the underside is in tension. 

Another sign of concrete sinking can be evidenced through gaps or separations between the skirting board and the sinking concrete or between the ceiling and the wall’s cornice.

Associated sinking concrete symptoms can be cracks in walls, unlevel floors or windows and doors that are no longer opening/closing easily or jamming. 

How do you fix sunken floors?

All types of floors can subside, but primarily we raise and relevel sinking concrete slab floors.

When we undertake concrete levelling to repair sinking concrete floors that have experienced this type of subsidence, we use all the signs of distress by ‘mapping’ them, as well as comprehensive level survey, to determine the safest and most cost-effective methods of releveling the sinking concrete slabs and returning them to level and closing the cracks in concrete. 

In most instances, we undertake a repair on the supporting structures or weak ground first before addressing the sinking concrete or cracked wall repair process. 

One method we use raising and releveling sinking concrete is called Slab Lifting where polyurethane resin injection under the slab through 10mm penetrations. The sinking concrete slab is then raised and relevelled a millimetre at a time until the desired levels are achieved. 

Injection holes are filled in with grout and virtually unnoticeable afterwards. There is little or no mess or disruption associated with this technique. Raise and Relevel believes it is often the best method for releveling sunken slabs. 

How Raise + Relevel Can Help You

Sinking floors can be a severe issue; if you allow the issue to go unaddressed, it can worsen. For example, if you have a white ant infestation, it should be dealt with immediately. Failure to do so is going to cause serious structural issues. The best way to prevent sinking floors is to take a proactive approach. For example, frequently check your crawl space for insect infestations or water damage. Inspect the internal and external walls and flooring for cracks, gaps, or other signs of sinking floors. The sooner you address issues, the more likely you are to prevent sinking floors.

You may have structural damage if you notice cracks in your floors, ceilings or walls. Another telltale sign is sloping floors and sagging floor joists. Another clear indication, particularly in older homes, is gaps between the sinking concrete and skirting board. Or gaps between the cornice and ceiling. You may also have a problem with doors and windows that jam or do not open or close quickly.

Luckily, the team at Raise + Relevel can help fix sagging floors and bring your home up to the current building code standard. Any foundation can sink, but our expertise is in concrete slab floors. We use a structural assessor to map the floor to find all the signs of distress so we can provide you with the most cost-effective and safe solution to relevel your flooring.

In some situations, we will repair support beams before we address cracks and sinking flooring. In others, Slab Lifting is the way forward which is an injection under the slab to raise and relevel the floor just a millimetre at a time until we achieve the desired level. Get in touch with us today to discuss your flooring issue, and we can start working towards the right solution for you.

choose us?


We give you better value.


Everyone you deal with is a specialist structural releveller.


We provide a fully guaranteed warranty on workmanship and materials.

Questions you should ask

Your home is everything to you and your family, so before going ahead with any subsidence repairs, we’ve put together a list of questions our customers should ask:

What actual experience in resin injection does the person quoting my job have?

We offer advice, not sales, so we don’t employ salespeople. The person who quotes your job does your job, and has been relevelling homes like yours for over 15 years.

How many homes have you raised and relevelled?

Our specialists have raised over 7,000 homes in total.

What guarantee do I get that the solution is permanent?

If the problem returns, we return. We provide a fully guaranteed warranty on materials and workmanship.

How do I know I’m getting the best value?

At R+R, we have no call centres, no sales people and minimal overheads, all of which enables us to provide the best value for our customers.

Why should I choose you?

R+R will deliver you better value, through real experience, with guaranteed results.