Vapour Insulation

[honky-tonk]

Ensuite shower enclosure on interior wall, have taken plaster board off and noticed the insulation has become mouldy in parts should i replace the insulation or is it ok not to use insulation and replace the plasterboard and tile.

[malagabob]

Was the plasterboard you took off of the correct type. The board the trade use now for wet conditions is coloured pale blue. Someone can confirm this

[The Builder]

Water vapour inevitably gets through tile grout and ordinary plasterboard Honkers.
The insulation's fine. You just need to use a "tile backer" board such as "Aquapanel". The plasterboard manufacturers make a board made for the job. The builders' merchants will have it in stock.