Ceiling Sag

What Buyers Should Know About Drooping Ceilings

Sagging ceilings are a common issue found during pre-purchase building inspections. At True Inspect, we assess ceiling conditions as part of every inspection — and when we find bowing, deflection, or signs of movement, we report it clearly. A sagging ceiling may be cosmetic, but in some cases, it can indicate a safety risk or hidden damage.

What Is Ceiling Sag?

Ceiling sag, or plasterboard movement, is when a ceiling appears to droop, curve, or separate from the wall junctions. It often results from plasterboard sheets detaching from their fixings — either due to age, poor installation, or water damage. Ceilings are expected to stay firm for decades, so sag is a signal something isn’t right.

Common Causes of Sagging Ceilings

Our inspections regularly uncover ceiling movement caused by:

Water damage from roof or plumbing leaks
Inadequate fixings (not enough screws, glue failure, poor workmanship)
Roof structure or framing movement
Heavy insulation or items stored above the ceiling
Material ageing in older homes (adhesive breakdown, nail loosening)
Foot traffic or damage from trades in roof space
Humidity issues (e.g. unvented bathrooms)

Often, it’s a combination: for example, a small leak and poor adhesive can together result in visible sag.

Signs We Look For

We assess ceilings room by room and note the following indicators:

Bowing or uneven surfaces
Gaps at cornices or visible sheet separation
Nail pops (small circular bulges in the ceiling paint)
Cornice cracking or misalignment
Ceiling that flexes with gentle pressure
Cracks along joins or tape separation
Gaps visible from roof void between plasterboard and framing

We also inspect the ceiling from the roof space where possible to check the fixings and note any movement or adhesive failure.

Why Ceiling Sag Matters

Sagging ceilings can have serious consequences:

Safety hazard — partial or full collapse is possible in severe cases
Progressive deterioration — once movement begins, it can worsen quickly
Linked issues — water leaks, framing defects, termites may be involved
Costly repairs — ranging from minor refixing to full ceiling replacement
Reduced property appeal or value

We take this issue seriously and always include it clearly in our reports.

How We Inspect and Report Ceiling Movement

As part of your building inspection, we:

Perform visual checks from below and above (roof space)
Use lighting and tools to confirm suspected sag
Take high-resolution photos to document sagging or fastener failure
Identify the likely cause and describe the extent of the issue
Classify the defect according to AS 4349.1:
- Minor Defect (e.g. slight sag or one nail pop)
- Major Defect (e.g. significant movement, multiple fixings failed)
- Safety Hazard (e.g. risk of collapse or water-damaged ceiling)

Our reports explain whether the sag is minor and cosmetic or whether further investigation or repair is needed urgently.

What Should Buyers Do?

If ceiling sag is reported:

Don’t panic, but do take it seriously
Request a quote from a ceiling fixer or builder
Fix the underlying cause (roof leak, excess load, poor ventilation)
Negotiate with the seller based on scope and repair cost
Ensure repairs meet standards, including AS/NZS 2589 for plasterboard installation

In many cases, minor sag can be repaired by rescrewing and patching. More advanced sag usually requires new plasterboard and refixing to modern standards.

For more information, download the full information pack on Ceiling Sag and Plasterboard Movement.

Includes visual examples, causes, Australian Standards references, repair options, and buyer advice.

Ceiling Sag

What Buyers Should Know About Drooping Ceilings

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