Exterior Framework For Rockwool?

[ILikeDIYS]

Hi, still in a predicament on my exterior summerhouse insulation.

Initially bought Celotex 30mm but was told the foil acting as a vapour barrier could cause mould underneath.

Walls are currently (from inside to outside): Plasterboard > Foil bubble wrap VCL > rockwool + 4x2s studwork > 2x 12mm OSB staggered > breather membrane.

Now I want to add exterior insulation before cladding.

I guess more Rockwool (50mm acoustic) is the right choice cos it allows breathability... but I need to screw some framework to the exterior before adding rockwool, otherwise the cladding will have nothing to screw onto.

Is there some type of metal framework I can use? Like I-beam shaped so I can tuck the Rockwool into it?

Also would the Rockwool attract any moisture seeping in through the cladding? I know they say moisture resistant but mine got wet in the rain and absorbed it like a sponge.

Cheers.

 

[^woody^]

but was told the foil acting as a vapour barrier could cause mould underneath.

Who told you that?

 

[ILikeDIYS]

Who told you that?

Don't really wanna leave a gap... seems pointless to do OSB > gap > Celotex > cladding which will take up 50mm altogether when I can get 50mm worth of dense Rockwool and have no gap.

 

[phatboy]

Don't really wanna leave a gap... seems pointless to do OSB > gap > Celotex > cladding which will take up 50mm altogether when I can get 50mm worth of dense Rockwool and have no gap.

Dense rockwool isn't going to do much for heat insulation....

 

[ILikeDIYS]

Dense rockwool isn't going to do much for heat insulation....

RW3? I have 100mm RW3 in the walls so an additional 50mm I figured would be as good for thermal as 30mm Celotex. Also it's mostly for sound insulation but yes need a bit of thermal too for winter.