Hi!

I've got a 50 year old house with crumbly, brittle plaster on the
walls - it's not on the verge of falling off but wherever there's a
chip/break in the surface the stuff around it just crumbles away. It's
totally dry (perhaps too dry) but blown in a few places and drilling
holes usually requires an attack of the polyfiller afterwards. In the
dinning room I've put 3 skim layers over the old plaster and this has
made it look nice and smooth but this illusion faulters at the drill
test.

Anyway, onto the walls in the new baby room that are going to have to
be resilliant to the (lack of) attention of a growing boy. I'm not
keen to attempt full-on plastering and we want to avoid the cost of
getting someone in so the only way left, it would seem, to have tough,
even walls is to put up plasterboard. But, my concern is that the
existing plaster ain't that great.

Is it advisable to take down the old plaster or, as a whole entity,
would you expect 50 year old plaster to be strong enough to hold
plasterboards dotted&dabbed into place? If the latter, should I repair
the old blown plaster first (seen the method in the FAQ list)?

Thanks for any advice,
David.