What is Slab Heave, How Do I Prevent It?

Slab heave, or excessive cracking in your slab, walls and ceiling, occurs when the foundations move significantly. It can be extremely costly to rectify, costing tens of thousands or in rare cases, hundreds of thousands of dollars to fix. Causes include poor design or construction plus moisture ingress or reactive clay soils. Filled sites, which expand and contract at different rates, may also be an underlying cause or contributing factor.

To prevent slab heave the slab must be correctly designed, correctly constructed and properly maintained.

Before the slab is even designed your engineer will carry out a soil test of the land. The foundations will be designed in accordance with the soil type. If your building is built on reactive soil or a filled site, foundations will be founded into the underlying soil. This may involve bored piers or bulk piers tied into the slab to transfer the weight of the building into the ground.

It is critical that the builder install your slab in accordance with the engineering drawings, Australian Standards and the National Construction code. Your slab should be checked thoroughly during the construction phase to ensure that it is being installed correctly. At the minimum your slab is required to be passed or failed by the building surveyor. Thorough builders will have their own internal checking process. In addition, you can reduce the risk of slab heave by employing your architect to carry out independent checks of slab compliance. ArchitectInspect inspectors will check that beam depths and steelwork is correct, and will also document what has been installed and where it does not meet requirements. This will give you peace of mind and help prevent costly disputes and disruptions.

Contact ArchitectInspect for a quote.