Retro fitting external insulation on garden room

[cjames1984]

Hi all,

I was just looking for a basic layer guide to externally insulating my existing garden room.
For reference the existing building is made up of 44mm timber.

I was thinking (starting from wall externally) rigid 100mm Rockwall screwed straight to existing timber using screws and discs(no stud wall), breathable membrane, 25mm battens for ventilation and then 19mm shiplap cladding.

Or

75mm foil backed PIR boards again screwed straight to existing timer using screws and disks, battens and cladding. I'm not sure about the membrane layer on this one because of the foil on PIR

I would be left with enough of an overhang on my roof with either install.

I just want to get it right so I minimise any build up of moisture inside the room.

Any advice is greatly appreciated

 

[freddiemercurystwin]

How would you use Rockwool without any timber studs?

If you want to avoid studs then you'd have to go the rigid insulation route, you still need a breather membrane and for the cost it would be daft not to, vertical battens & horizontal cladding presumably?

 

[cjames1984]

Thanks for the response.
My local builders merchant does accoustic rockwool boards rather than the rockwool that comes in a roll.
Yes, vertical batons and horizontal cladding. If I go down the rigid insulation route where does the membrane sit in the layers?