DISTRESSED OR CRACKED BUILDINGS

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Movement and distress in low rise residential and commercial buildings most commonly occurs as a result of interactions between the footing system and the ground. As a consequence such problems fall within the Geotechnical field of expertise rather than the structural engineering field. 
The soil profile across almost all areas of metropolitan Melbourne and most of country Victoria contains reactive clays. Reactive clays are clays that change volume with variations in moisture level. When a reactive clay becomes wet it will swell and when it dries it will shrink.
Reactivity or the shrinking or swelling of foundation clays caused by moisture variations is the single most important factor that influences footing movement and therefore damage and distress to low rise residential and commercial buildings across Melbourne and country Victoria.

There are a vast number of factors that can influence soil moisture levels to the extent that is sufficient to cause movement and damage to buildings. These factors can be interrelated which further complicates the effects and increases the difficulty of determining the main causes of the movement and damage to buildings.
Unfortunately there is a lot of incorrect information with regard to the main causes of movement and damage to low rise residential or commercial building across Melbourne and Victoria. This information comes from a variety of usually non expert sources and circulates mainly through the media.
One of the more common misconceptions is that the natural clay soil beneath a footing will wet up to the extent that it will deform beneath the load from a low rise residential or commercial building. Even when a clay is close to its maximum natural moisture content it is still likely to provide adequate bearing capacity to support the normally expected loads from a low rise residential or commercial building. As a result of this, bearing failure which is the soil not being strong enough to support the footings of a low rise residential or commercial building almost never occurs.
Our Geotechnical Distress Investigation Reports identify the underlying cause or causes of the movement and distress that has occurred in the building. These reports then set out a method of action to fix the problem. The method of action to fix depends on the cause but usually rectification measures consist of a number of integrated steps. The first of these steps is obviously to identify and address the underlying cause. The second step is usually to monitor the movement and distress until it can be established that most significant movements have stabilised this normally takes approximately six to eighteen months. The final step is the actual repairs to the damage which can usually be completed reasonably economically, particularly compared to underpinning which often does not address the underlying cause of the movement.
After considering the above it is clear that Distressed or Damaged Building Investigations and Reports should only be undertaken by qualified and highly experienced professional practitioners who must have a detailed understanding and knowledge of all of the Geotechnical factors that are likely to influence the movement of a building. These Investigations and Reports should only be undertaken by Registered Building Practitioners who carry current and appropriate Professional Indemnity Insurance.  

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Common Signs of Movement and Damage:
Cracks in bricks, cracks in brickwork, cracks in plaster, cracks in walls, diagonal cracks in plaster, door frame distortion, window frame distortion, gaps in walls, gaps between window frames and brickwork, gaps between door frames and brickwork, gaps between window sills and brickwork.

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