geraldthehamster wrote:
I'm going to use moisture-resistant plasterboard for the ceiling of a
shower room in my renovation. This will be screwed under 3x2 ceiling
joists, with rock wool above. How moisture-resistant is it, and would
I be wise also to install a vapour barrier? The roof space above the
ceilings is ventilated (soffit vents and vented ridge tiles).

If relevant, this is the first floor of a dormer bungalow, so the roof
space left above the ceilings is pretty small.

Regards
Richard

Ive got perfectly standard plasterboard above my showers. No problems.

Unless you deliberately spray the ceiling water generally comes
downwards out of showers....