I stripped the wallpaper from a bedroom last night to find the plaster was rather more 'blown' than expected.
The house was build in about 1870. The affected walls are lath-and-plaster. Laths have a grey plaster coat of about 10mm - hair filled, so I presume it's the original lime plaster? Then there's a 3mm or so pink gypsum ('modern') plaster skim over the top.
In many large patches the gypsum is no longer bonded to the underlying plaster, so it's crumbling off. However, after digging a few holes, the grey plaster doesn't seem to be attached to the laths properly any more
- the keys are still generally attached and sit round the lath, but there's play between the plaster and the lath - they're not connected.
The whole wall in these large patches is 'springy' - there's a fair bit of give if you push it. You can hear the grey plaster cracking and crumbling as you do that. The grey plaster is pretty dry and crumbly in my fingers.
So... is that stuffed? (or, say, is some springyness to be expected) If so, can it be repaired at all, or would it be easier/better to redo with skimmed plasterboard? If so, I guess I could nail/screw plasterboard over the top of the existing lath/plaster into the uprights, but it would seem more sensible, though messier, to completely strip back to the uprights and start again?
[No issues with listed buildings or conservation area stuff here..]Any suggestions or advice?