Discovering cracks in the walls and ceiling of your home can be alarming. After all, for most of us, our home is our single largest financial investment.
While some cracks are superficial and require only cosmetic repairs, other cracks can indicate the presence of serious structural issues. Ignoring cracks can lead to further deterioration, potentially compromising the structural integrity of your home. Significant cracks can weaken load-bearing structural members, leading to partial or complete structural failure. They can also allow water ingress which can cause additional damage and promote mould growth. Moreover, unresolved structural issues can adversely affect your property's value and marketability.
What you should know and what you can do when you notice a crack in your wall?
Structural engineers classify cracking as either active or dormant. So firstly, measure the width of the crack by marking the ends of the crack with a pencil. Secondly, monitor the length and width of the crack over time. If the crack is active, the length or width (or both) will increase, which is indicative of an active crack. Identifying a crack as active is cause for concern and it is recommended that a structural engineer be engaged to inspect the crack to determine the cause and possible remedial repairs to prevent further damage. Addressing the cause of an active crack early is essential to avoid more expensive repairs later.
Types of cracks and the mechanisms that cause them
Hairline Cracks
Hairline cracks are very narrow cracks often less than 0.25mm in width and are normally dormant after initial formation. These are not considered to be structural cracks and while unsightly need only cosmetic repairs.
Foundation or Soil Movement Cracks
The foundation of any structure is designed to transfer the weight of the structure to the ground below.
Foundation movement is the most common cause of cracking in walls and ceilings. Structural engineers describe any movement of foundations as deflection, which includes:
- Vertical Deflection: Where parts of the foundation sink or rise unevenly.
- Lateral Deflection: Where the foundation shifts sideways.
When foundations deflect they no longer evenly support the structure above incurring localised force concentrations that exceed the intended design capacity, which frequently presents as cracking. Movement becomes problematic when the soil beneath a foundation moves or experiences changes in its moisture content.
Foundation settlement may be the result of inadequate structural design, or overloading of foundations, where imposed loads from the structure exceed the bearing capacity of the ground below the foundation. Another common cause of foundation settlement is due to undermining. This is where material below the foundations is removed through natural or induced processes. Natural processes may include erosion of soil adjacent to the foundations caused by the movement of water over or through the soil. Induced processes may vary from excavations adjacent to foundations, retaining structure failures, or excessive vibrations impacting the stability of the surrounding earth.
Problematic soil profiles may also induce movement in foundations, this is due to the fundamental properties of the soil material. These include heaving and shrinkage actions from expanding clays. Variations in moisture contents for collapsing sands. Soluble materials such as limestone or dolomite are susceptible to collapse due to water ingress or chemical attack through acids or other polluting compounds. Uncompacted fill materials or settlement of reclamation areas from mining or landfills.
Structural Cracks
Walls in your home are designed to transfer loads to the foundations. These may be vertical loads such as the roof and storey above exerting downward pressure, or lateral loads such as wind loads exerting lateral pressure. When either of these loads exceeds the design capacity of the wall, movement, cracking, or even total structural failure can occur.
When renovating your home, you are altering its structure which may, in turn, result in additional loads being applied to your walls, which exceed the design capacity of the walls, resulting in structural overload. Alterations to load-bearing walls, such as creating new door or window openings change the way loads are transferred through the structure, increasing local stresses.
Shrinkage and expansion cracks
Shrinkage cracks may also occur due to temperature differentials, all materials expand and contract under changes in temperature this is referred to as the material thermal expansion coefficient. When materials heat up, they increase in volume (expand) and when they cool down, they contract in volume (shrink). When structures move due to thermal effects but are not adequately designed and constructed to accommodate the movement, the structure or local element will fail or crack, at the weakest point.
Moisture variations, including leaks from plumbing or roofing and high humidity levels, weaken building materials, induce swelling, and contribute to cracking.
Shrinkage cracks may form during construction in concrete walls or plastered masonry walls, where the concrete or plaster contracts as the heat of hydration dissipates. This is normally controlled through curing, jointing, and sequencing. Cracks will become dormant after initial settlement but may cause concern through effects like moisture ingress.
Construction defects
Furthermore, poor construction practices, inferior or inadequate materials, poor workmanship, or non-compliance with building codes, can lead to several structural problems including cracking.
Site inspections and evaluation by Inhouse Consulting Engineers
Over the past 35 years, Inhouse Consulting Engineers has competently carried out over 20,000 commissions. Such is our reputation as leading forensic and remedial structural engineers, we are entrusted by Australia's largest insurers including:
- NRMA
- IAG
- Allianz
Between these firms, we have completed over 1,000 remedial investigations alone. Our experience and expertise in forensic and remedial structural engineering are equally valued by the strata industry for who we have undertaken over 500 engagements.
At Inhouse Consulting Engineers, we follow rigorous standards and guidelines set by Australian regulatory bodies, including Australian Standards and the Building Code of Australia (BCA).
Our diagnostic assessment includes a thorough inspection of your home by qualified and highly experienced structural engineers to determine the extent and likely causes of cracking observed. We provide you with a detailed report of our findings including any remedial repairs required.
Whether your home requires minor cosmetic repairs or more extensive structural remedial works, our team is dedicated to delivering industry-leading solutions that meet the highest standards of safety and quality. Contact us today to have one of our experienced structural engineers inspection your home and give you peace of mind!