I’ve just completely redone a room (Jnr’s new bedroom) from floor joists to removing a window into the garage. All that remains is the ceiling but the ceiling is warped wood joists (twisted and bent) around 50mm thick and at one end is directly under the Eaves (cold roofing)

The top is some compressed paper/fibre board ….
What I’d like is to insulate and cover it up… cheap but not crap but the downside is my shoulder won’t last for plastering a ceiling. [it will keep dislocating and need rest which would make plastering impossible, I can get away with limited stuff above 45 degrees especially if I can stop]

Normally I’d shim the joists straight (also allowing some 50mm insulation), stick in some insulation and stick on plasterboard and plaster…but I’m looking for alternatives

Use tapered edge boards, tape and fill edges then seal the face. One thing to bear in mind though, if your joists are twisted you might end up with a few lumps and bumps in the ceiling. Might be worth counter battening first.

Sounds good… do the counter battens need to be the same sort of thickness or can I get away with something thinner? I don’t want to drop the ceiling too much in part due to him now having a bunkbed.

If you watch Scott Brown Carpentry on YouTube, they do some plywood walls and ceilings with shadow gaps. Looks really good (imo), om thinking about doing it on my garden office as alternative to plasterboard / skimming

I would use a 2″x1″ or better still gypliner channel (Google it – Travis Perkins etc can get it for you).

Our kitchen ceiling collapsed due to water leaks from the bathrooms above. There’s always the possibility of more water damage, and it’s useful to be able to access the pipes without taking the floor up, so I put in ceiling tiles. Support the metal grid on wire hangers 10cm below the joists and just slot the tiles in. You could put the grid closer to the joists but I wanted space to fit LED downlighters as well.