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Subsidence-Wall cracks/Ceiling cracks what do i need to do.

Cracks in walls,ceilings around windows & doors may occur for several reasons.

Most cracks are cosmetic and are not a serious problem. However cracks that are more than 5 mm wide may be a sign of a more serious structural problem.

The Building Code of Australia has defined tolerance levels that apply to how a slab and footings must be designed & constructed.

Subsidence can occur because of moisture & temperature changes. It can also occur because of the ground compressing under the load of the building.

If you notice that the windows & doors are uneven or have gaps. Windows & doors are hard to open/close there may be a subsidence problem.

Hairline cracks in concrete slabs that are less than 2 mm wide are not usually classed as a major defect. Sometimes a concrete slab will settle & cause a change in level this is accepted as normal for this change to occur.


The building code of Australia provides guide lines to determine when cracks are a serious problem.

Hairline cracks to walls,ceilings concrete slabs that are less than 5 mm wide & can be easily filled & repaired are with in the normal range.

Walls that are bulging & have cracks that are greater than 5 mm in width that can not be repaired do not fall within the tolerance level.


Cracks that fall into the acceptable range are the responsibility of the owner to repair.

If your house is less than 6 years old your home may still be covered by builders warranty. Your builder may be responsible to rectify these problems, contact your builder & talk to them about the problems.

How is a major defect determined?

A two-step test will determine if a problem is a ‘major defect’. To be considered a ‘major defect’ it must meet the criteria of both the first step and then the second step.

The first step is whether the defect was in a major element of the building. A major element is a fire safety system, waterproofing or something essential to the building’s stability or structure such as foundations, footings, walls, roofs, beams or columns.

The second step considers the defect’s potential consequences. This includes whether the defect will cause or is likely to cause:

  • part or all of the building becoming uninhabitable or unable to be used for its intended purpose, or

  • the collapse or destruction of the building or part of it.

For more information go to ABCB Australia.

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