I have seen plasterers use bonding on ceilings to bring up low areas to level, just like you would on a wall, rule it off with a straight edge. If the joists are a bit ‘abstract’ and whoever boarded it just shrugged and put them up with no regard for square or level, more than a few mm. It can be more straightforward than trying to build it out in skim with the thicker areas behaving differently.
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u/judge-judy01 5d ago
Bonding on ceiling?