Hi, the ceiling is original, and seems to be some sort of plasterboard. There's an area about 18" x 10" of the landing ceiling which appears to be damaged. The surface is papered and painted, and there is a crack. The plaster is dry, loose and cracked from the sound and feel when I push gently- elsewhere it's solid.
My guess is that when the loft conversion was done many years ago, someone knelt on it or put their foot on it.
Redoing the whole ceiling would be a massive piece of work- I was advised it would likely mean redecorating the whole staircase, hall and landing.
I'm wondering about supporting the area (holding it back in position as it has sagged slightly), then drilling a number of small holes and injecting PVA into them and letting it set.
The area is near the wall in a corner above two door frames, which I could use to support a light framework and hold the damaged plasterboard in position.
Is this worth trying? Other ideas welcome. Thanks. David