Cracked plasterboard

[Matt54]

Hi all

I live in flat converted from a 30s mid-terrace house. I recently pulled down polystyrene tiles in the study as I know they are a fire risk. I knew it was likely to reveal some unpleasant surprises. it looks like the plasterboard underneath has a lot of cracks on it (see attached pics), and for some reason in the corner it looks like some plaster or adhesive paste has been used to fix some of the tiles, which look like it'd be a pain to get rid of.

Do I need to replace the plasterboard? Or could I get away with fixing the cracks with some sort of filler and painting, and also should I be worried about all the cracks appearing in the first place!? I'm also a bit paranoid that it looks like the darker patches might be water related...

I'm a bit stumped about how to deal with it to be honest and would really appreciate any advice. Thanks

 

[Murdochcat]

You should seriously consider over boarding and then plastering if you want a decent finish to last a while

 

[Wayners]

That's not plasterboard by looks of it. Lath and plaster ceiling

 

[Matt54]

Thanks, I probably will do that I think... It probably looks a bit worse in person than comes across in those pictures.... A thought the house was built too late for it to be lath and plaster, but that would make more sense

 

[Wayners]

Board sounds hollow when you knock.
Cracks tend to be straight and at right angles following the shape of plasterboard.

Your cracks go all directions