Common defect myths: what isn’t actually a defect

Half of all “defect” disputes are really expectation disputes — natural material behaviour or normal tolerances that the owner reads as poor work. Knowing what genuinely isn’t a defect saves you from arguing over things that were never your fault, and it lets you set expectations before a complaint ever lands.

Set expectations at handover

Walk through these with the owner at handover, before they become a complaint. Explaining that timber moves, that concrete gets hairlines and that decking gaps open up is normal turns a future argument into a moment that builds trust.

All of the points below are covered by the MBIE Guide to Tolerances and the defect provisions of the Building Act.

What is not a defect

These are the natural material behaviours and normal tolerances owners most often mistake for poor work:

• Imperfections only visible at low-angle (‘critical’) light.
• Cracks ≤3mm in concrete — common, and not necessarily poor work.
• Timber decking gaps of 2–12mm from seasonal expansion.
• Squeaks in floors — some are expected; only excessive squeaking counts as a defect.
• Surface checking on standard or merchantable (merch) grade timber.
• Discolouration of asphalt patches, which lighten over time.
• Damage caused by the owner delaying maintenance.
• Wear and tear after 12+ months.
• Hairline shrinkage cracks (≤0.3mm) in plaster or concrete.
• Mortar efflorescence on brick, which washes off over time.
• Natural timber silvering or weathering where the timber is left unfinished.

The one to watch

The common thread is degree, not presence. A hairline crack, a floor squeak or a decking gap on its own is expected material behaviour — it’s only when it’s excessive that it crosses into defect territory. Squeaks are the clearest example: some are normal, but excessive squeaking is a defect.