geraldthehamster wrote:
On 28 Oct, 14:16, wrote:
On Oct 27, 7:40 pm, (Andrew Gabriel)
wrote:





In article ,
The Natural Philosopher writes:
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....
That was my thought too.
Actually, the ceiling in one shower does get wet sometimes;
if you turn that shower on too much, water blows past all
the seals in the showhead and soaks the whole bathroom.
Still, the ceiling hasn't come to any harm -- it usually
just rights off a toilet roll on the other side of the room.
Shower ceilings can get wet every time, due to steam & condensation.
Standard PB seems happy enough in this situation, as long as the room
dries out after use.


It's interesting that several people are considering this in terms of
damage to the ceiling, which isn't the issue. The issue is whether
water vapour is penetrating the PB into the roof space - which it
will, with standard PB without a vapour barrier. Not that this is
likely to be a problem, provided the roof space is ventilated.I
wondered whether moisture-resistant PB would remove the theoretical
need for a vapour barrier - which nobody seems to know ;-)


Probably, but since all you need for a vapour barrier is cheap foil
backed board, who cares?

Regards
Richard