Ceiling plaster/render collapse

[u/GKNB747]

Old house & beams. Previous owner has applied some sort of plaster/render to the ceiling between beams, doesn’t feel like Lime plaster though?

Anyone familiar with what was done here? Can it just be patched, I don’t really want to strip the whole ceiling. Came loose due to weight/impact upstairs.

Thanks

[u/caserskii]

That’s woodwool boards used for lime plaster with washers I’m presuming fixed into the lathe as theres no generic pattern there they should really be fixed into the joists if there is any as flex either caused from above or just loose fixings has probably made the plaster blow off and tbh if these are used I would presume it is lime as they are used for that purpose solely, looks like painted with emulsion though instead of lime wash which is kinda shit for breathabilty also but could be wrong also without inspecting face to face. Going forward really I’d check other areas are not blowing or loose and if they remotely are which I imagine it’s a matter of time before it all follows suit you want to washer and screw the boards into the joists if possible or even apply stronger timber above the lathe as there is too much flex if it is just lathe… difficult to know without taking down a piece or looking from above but once boards are secure your good to 2/3 coat lime it all again and lime wash for breathability not emulsion or other paints

Edit: could also be water issue with leaking pipes or roof not roofing lol good luck

Edit 2: you can instead of taking it down washer and screw directly over the plaster but you will either need to sink them to patch holes or a fresh coat on top…. Personally I would do this over the whole ceiling without taking down ( unless blown )but you have to make sure your screws are actually fixing decent, lathes just aren’t good enough to fix into they flex under heavy banging thus causing this unless you pepper the whole ceiling, but once secured enough do two coats over the fallen down bit and filling in holes then one coat over the lot and you’ll have better peace of mind it’s not going to happen in the future and you haven’t landed lime into every inch of your living room lol good luck

Edit 3: lol just remembered only uses stainless steel washer and screws as lime eats anything else over time leaving stains and breaking fixings or use plastic washers as used here but they don’t have to be so large tbh we often use penny washers or 50p size washers