Client flooded bath. Resulting in section of ceiling collapsing in flat downstairs. Damage minimal, just old plaster separated from lathes in a section 2 metres square. Question is: do I bond straight onto the existing lathes and then skim or do I cut the lathes back to the joists and fit plasterboard?
I'm only a dafty DIYer but I reckon I know the answer to this - over board and skim. Why make the job complicated? Does your client know you're struggling with this?
Cut out the lath square and put a bit of plasterboard up there. The odds are the water has made other parts of it loose as well. Always do things properly.
Remove loose plaster then either: paint laths with a PVA, tight coat of bonding let it set another coat of bonding (if the laths are good and tight and close enough together then you might do it in one coat)then skim, or; check the thickness and see if you can get a 9.5mm plaster board on, sometimes this means having to cut the laths back as well but it's certainly quicker although the second method has more chance of cracking.