What causes building defects and why they happen

What causes building defects and why they happen

Understanding the root cause of building defects and why they’re so common


Defects can happen at every stage of the building and construction process. However, studies have shown that
50-60 per cent of defects happen because of design issues or could have been preventable with better design. This means that 40-50 per cent of defects arise in the construction phase.
While knowing where defects are most likely to happen is helpful, knowing why they happen is the key to taking steps to prevent them. The root cause of defects in Australia is largely put down to two major categories: human error and organisational practices in building and construction.

Human error includes poor workmanship, incompetence, poor supervision, lack of skills, lack of knowledge and lack of motivation, which leads to forgetfulness and carelessness when working.

Issues with organisational practices referrers to the operational issues between the builders or developers and property owners. Major organisational issues include churn — key project managers leaving the job, lack of project control, regular changing of plans or minds, and a lowest bid or cost wins mentality, meaning property owners will often pick the cheapest builder, developer, product tender, or tender which results in sub-optimal outcomes.

What’s more, research shows a higher likelihood of defects when:

  • The building’s design is developer-led as opposed to owner or architect-led
  • The developers or builders are inexperienced
  • There is an absence of project management
  • There is a private certifier as opposed to a council certifier
  • The detailed design is done by subcontractors as opposed to architects
  • The property has been purchased off the plan
  • It is a larger building with more apartments, or it is a complex building which means the work becomes repetitious and mistakes are made due to monotony, and tighter time schedules forcing workers to rush.

Do your due diligence to avoid or minimise the chances of defects

When it comes to defects, it’s best if they can be avoided altogether. Tips for avoiding defects or reducing the chances of them, whether you’re buying, looking to do renovations or rectification works, include doing your research on the builder or developer. Find out their previous projects and buildings and inspect them. Don’t hesitate to get in contact with residents (like knocking on their door) to ask them how they find their building, do they have any issues, and if they are happy with that builder or developer. Ask if they would recommend them.

You also need to do your due diligence throughout the construction or rectification process. It might take a bit of effort, but it’s worth it in the long run.


  • Checking and understanding the building standards and tolerances guide for your state
  • Getting a legal professional to review all contracts and explain the current building code and legislation to you
  • Check all manufacturing guides and warranties to understand the products being used on your building and what their limitations or life expectancy is
  • Check all builders, developers, and subcontractors are appropriately qualified and insured
  • Document the construction process. Take photos, write down notes about conversations and outcomes and ensure you develop a record of the process. Doing so will help if you end up in a legal dispute over a defect
  • Where possible, work with the most skilled practitioners in the field such as architects and engineers with good reputations.

Knowing what causes building defects and why they happen can help to reduce your incidences with them or the severity of how they impact you and your building.

If you’d like to find out more about building compliance for your strata property, download our FREE Community Living guide. Or for a consultation to review your common property insurance by our CommunitySure insurance team, click here.

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