Slab Heave – When the Earth Moves Beneath your Feet
By Jarrod Gutsa, Construction Lawyer at Lovegrove Smith & Cotton
What is slab heave?
Generally, slab heave is movement of the foundation slab relative to the other sections of the house due to soil movement.
Even though recent media coverage might suggest otherwise, slab heave does not always result in significant damage to the home. Damage can range from door and windows sticking, to distorted door and window frames, and at the severe end large and pervasive cracks throughout the superstructure .
The causes of slab heave are legion. But primarily, they occur due to soil contraction and expansion attributable to the ingress of moisture. This can occur because of unseasonably heavy rains after drought, leaking underground pipes, poor drainage of the site etc. In one case, an investigation of a house in Adelaide revealed that “…the major cause of house distortion could be attributed to service pipe leaks across the site and excessive garden watering which resulted in non-uniform soil moisture conditions.” Owners of verdant lawns, beware!
Who is responsible when the house goes sideways?
Nobody wants to cop the blame when things go bad. However the owner will have in their sights both the geotechnical engineer and the builder. A geotechnical engineer investigates the ground conditions on site before building commences and recommends remedial action if needed. In some cases, they are also engaged to design an appropriate foundation. The owner may also be the cause of their own undoing as the owner’s own actions (i.e. by building unauthorized extensions, overwatering the lawn, or failing to obtain geotechnical reports contrary to advice) may have contributed to the damage.
When the builders are responsible?
In a recent decision of 2014 an Australian builder was found to be responsible for slab defects. In this case two months after the owner moved in, cracks started appearing. These became increasingly more severe over time. After obtaining expert advice, the owner brought proceedings claiming damages and loss of rent. The claim against the
geotechnical engineers (“Engineers”) was in negligence whilst the claim against the builder was in contract for breach of the statutory warranties included in the contract by the Domestic Building Contracts Act 1995 (VIC).
It was held that:
- The Engineers owed a duty of care to the owner and there was a breach of that duty of care in the design of the slab because it did not conform to AS 2870-1996. But having said that, the design was nevertheless adequate for the purpose as a design under Concrete Code AS3600 and in the absence of proof of actual damage attributable to the design, the Engineers were not liable in negligence.
- In any event, the builder had not built the slab as designed by the Engineers. The site was inadequately prepared and workmanship of the slab defective. It failed to comply with the statutory warranty that the work would be carried out in a proper and workmanlike manner and that the work would be carried out with reasonable care and skill.
It is now clear in the field of domestic building that builders and Engineers owe a duty of care to the owner and subsequent owners of the property either through the general tort of negligence or the statutory warranties that are expressed to run with the land.
When the geotechnical engineer is responsible?
The geotechnical engineer was found to be largely responsible for the damage to the house and liable to indemnify the builder in Gino & Associates Pty Ltd (“Ginos”) v NBD Bank NA (Formerly known as National Bank of Detroit)(“NBD”)  SASC 6646.
A house in Urrbrae, South Australia was built and after NBD, the owners of the house had taken possession, the house began to show signs of structural distress. The house had to be underpinned at the cost of $54,120.00. NBD then sued the builders and consulting engineers for the project. Ginos were the consulting engineers for the project. They had obtained soil samples and assumed that shale laid about 1.5 meters below the surface of the land. This assumption proved to be incorrect. The depth of the shale varied throughout the side, and thus were found to be liable.
Damages – Diminution of Value or the Cost to Rebuild
In the recent decision referred to above it was considered whether the damages for a defective slab, should be assessed on the basis of a diminution of value or for the cost to demolish the dwelling and rebuild it.
Diminution in value is calculated as a hypothetical equation of what the dwelling with its defects would sell for on the property market as compared to the dwelling without the defects. Calculation of damages on the basis of a diminution in value was rejected.
Instead it was found that the owner in accordance with Bellgrove v Eldridge  HCA 36 was entitled to damages calculated at the cost of demolishing and rebuilding the house. 
A claim against a builder or engineer for a defective slab is a complex area of law that requires input from multiple expert witnesses, and lawyers that are well versed in construction litigation.
To find out more about when a concrete crack can be considered a defect, please click here.
By: Jarrod Gutsa, Construction Lawyer, Lovegrove Smith & Cotton.
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© Lovegrove Smith & Cotton 2014