Insulating over hips in loft bathroom?

[Ian H]

The wood is 300x50 c24.

I measured and I would need 120mm PIR to loose the hip so i'm going to go with FMT's suggestion of a thinner board and plaster board over it with and gaps foamed and taped.

I've used 7x 45mtr rolls of 100m foil tape so far

 

[Ian H]

Just don't use normal plasterboard in a bathroom
which ever way you approach it.

Use the green stuff?

 

[catlad]

I would probably use foil backed plasterboard
but the green stuff is moisture resistant?

 

[Ian H]

I've got a load of foil backed but used the green moisture resistant in the bathroom downstairs. I think it has loads of silicone in it?