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Generally speaking, many visible cracks in concrete are actually safe. It’s natural for hairline or superficial cracks to appear over time as the concrete and ground below settles. In fact, it’s very rare for ASBIR to complete a residential or commercial building inspection that is completely free of any concrete cracks.  

So when should you get an expert to assess if there’s a bigger issue at play?  

As a rule of thumb, if a crack wider than a debit card and if it runs the depth of the concrete it could be a sign of a bigger, structural problem and should be investigated further.  

Five common reasons concrete cracks  

Here are the most common reasons concrete may crack:  

1. Shrinkage 

Concrete shrinks as the excess water evaporates and the concrete dries and hardens. Unfortunately some contractors will add too much water to the cement mix making it easier to pour and handle, but more  vulnerable to cracking. 
ASBIR Inspectors recommend control joints, or the grooves you see at regular intervals along the concrete, to help relieve the pressure that leads to cracking.  

2. Settlement  

Concrete typically takes at least a month to settle and really harden and should be “cured” during this process, which means regularly moistened. It’s important to note weather can also affect the settlement or hardening process. 

3. Heavy loads 

Concrete cracks caused by heavy loads are usually structural cracks and should be checked by a structural engineer. They are caused when the concrete has been overloaded or the slab has insufficient support. 

Always be mindful about the weight or load of trucks or vehicles driving over existing concrete, or speak to your concreter before you pour a new slab or driveway about how it will be used to ensure the concrete won’t be compromised down the track.

4. Corrosion 

Corrosion occurs in concrete when the steel reinforcement (rebars), laid before the cement is poured, are installed too close to the surface of the slab. They can rust which will can lead to concrete staining and cracking.  

5. Movement of the surrounding soil 

This typically occurs when areas surrounding the concrete have not been properly retained or landscaped, or the concrete footings have not been installed correctly. 

What type of concrete cracks require repair?  

The most common concrete issue that requires attention is when the concrete surface, most often a driveway or pathway, has subsided and creates a trip hazard.  

Subsidence occurs when the ground below caves in or sinks.  

When this occurs in a driveway or pathway, this biggest concern is getting it repaired to ensure your family or any visitors to the property don’t hurt or injure themselves.  

Although more rare, subsidence can also occur in the concrete slab of a house or building. This can result in significant structural damage to the entire property. As evidenced in this recent Building Inspection Report we conducted in Bellmere, Queensland

Subsidence is usually evident by the changes or movement of soffit sheets, moulding and brickwork that ‘subsides’ lower or moves away creating gaps in brickwork or potentially pulling paster ceiling and cornices away from other walls.  

What should I do if I notice cracking in my concrete?  

Any cracking should be monitored over time for further movement and rectified urgently if it becomes a trip hazard. 

If you’re concerned that any part of your concrete may have subsided, we recommend contacting us for an independent building inspection as the first step.

Depending on your personal circumstances – whether you are the home owner or tenant – you may be able to claim any damage on your insurance.  
Whatever you do, don’t overlook subsidence issues as they will only cause more headaches down the track. 


All Suburbs Building Inspections and Reports (ASBIR) is the leading provider of building inspections. We have conducted thousands of residential and commercial pre-purchase building and pest inspections in South East Queensland. We are fully licensed (QBCC Lic.No. 20650) and a Member of Master Builders Queensland.     

Call us on 1300 553 007 or submit a quote request to find out how we can help you take the hassle out of buying or building a new home, or finding the perfect commercial, office or retail space for your business needs.  Let ASBIR give you peace of mind.


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All Suburbs Building Inspections and Reports recently completed a practical completion handover report for my investment property. As I am interstate it was crucial that I had an experienced team to look after the handover. ASBIR provided me with peace of mind knowing that they would look at every single detail of the property to ensure a smooth and stress free handover. The report was very detailed and provided the builder with specific information with what needed to be completed and fixed for handover. I will definitely use ASBIR again.

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