What is a plasterboard ceiling joint?
Plasterboard ceilings are installed in sheets. The edges are joined using tape and layers of setting compound, then sanded and finished so the individual sheets appear as one continuous surface. Recessed-edge joints and butt joints require different feathering widths, and strong lighting can make even small variations visible.
Signs that a ceiling joint has failed
- A long straight crack across the ceiling.
- A raised ridge visible under side lighting.
- Tape bubbling, lifting or showing through paint.
- Repeated cracking after previous filling.
- Popped fasteners near the joint line.
- A joint crack combined with sagging or sheet movement.
A fine stable line may be limited to the finish, while widening cracks, bowing and popped fixings can indicate movement or support problems that should be assessed before the joint is repaired.
Why plasterboard joints crack
Common contributors include movement between sheets, insufficient backing, fixing movement, poorly bonded tape, inadequate compound, moisture, heat changes, building movement and previous repairs that did not extend to sound material. A crack can also return when a moving ceiling is filled without re-securing the sheet.
How a failed joint is repaired
- Inspect the crack pattern, surrounding ceiling and any signs of movement.
- Confirm that moisture or another cause has been controlled.
- Remove loose compound and tape to a sound boundary.
- Re-secure suitable plasterboard where required.
- Apply new tape and staged setting compounds.
- Feather, sand, seal and repaint to the agreed boundary.
Where the sheet is damaged or the joint sits within a compromised section, local replacement may provide a more reliable base than repeated patching.
Butt joints, recessed joints and visible lighting
Recessed edges create space for tape and compound. Butt joints meet where the sheet has no recess, so the finish must be feathered across a wider area to make the transition less visible. Windows, downlights and other raking light can emphasise small surface changes.
The quote should state whether paint is a local touch-up, a defined ceiling section or the complete room. See ceiling repair finishing and paint matching.
Plasterboard joint repair cost
Minor ceiling repairs generally range from $180–$550. The cost rises where the joint is long, difficult to access, connected with sagging, requires sheet replacement or needs a broader painted finish. CRP confirms the repair boundary and final price in writing.
Frequently asked questions
Can a straight ceiling crack simply be filled?
Filler may not last if the tape, support or sheet is moving. Recurring cracks should be opened and assessed to identify the appropriate repair method.
Why can I still see the joint after painting?
Joint shape, sanding, sheen, texture and lighting affect visibility. Butt joints and strong raking light often require wider feathering and a carefully agreed paint boundary.
Does the repair include a warranty?
CRP provides a one-year warranty on ceiling repairs, subject to the written scope and warranty terms.