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Hey all! I just noticed a split with a bulge next to on the plaster ceiling in our bathroom. I’m just wondering the best way to fix it and if there’s anything else I need to be concerned about/check before repairing? I assume it’s at the join of two sheets of plaster as it’s a fairly straight line in the middle of the ceiling. It only goes for about 20cm, it’s not the whole ceiling.
You are most likely right that this is along a join between two plaster sheets @Joshuam08. A split with a slight bulge like that is usually a sign that the plasterboard has moved away from the ceiling joist. In a bathroom, the most common reasons are a small amount of moisture getting into the ceiling space over time, the sheets not being fixed particularly well in that area originally, or the stud adhesive that was used to help hold the sheets to the joists letting go.
Before repairing it, it is worth doing a bit of investigation if you are comfortable to do so. If you can access the ceiling space, have a quick look for any signs of moisture such as staining, damp insulation, or a plumbing issue above that spot. Even if there is no obvious leak, ongoing humidity in bathrooms can still contribute to this sort of movement. If everything looks dry, then it is more likely a fixing issue rather than active water damage.
To repair it, a stud detector will help confirm that there is a joist running along that joint, which is usually the case. You can then pull the plasterboard back up tight by driving plasterboard screws through the ceiling and into the joist on both sides of the split. Spacing the screws at around 150 millimetres along that section should be enough to flatten the bulge and secure the sheets properly. Once the ceiling is firm again, you can fill over the split and the screw heads with a suitable plaster filler, sand it smooth once dry, and then repaint the area.
Here's a helpful guide: How to use a stud detector.
Please let me know if you have any questions.
Mitchell
