Insulating Single Skin Detached Garage

[Harrier23]

Looking at insulating my single skin detached garage walls with 50mm polystyrene boards between treated roofing battons, possibly with foil therma wrap over the top for extra insulation.
I would then be placing either 12mm plasterboard or MDF over the top.

I'm not needing the garage to be as well insulated as the house, but just enough for it to be used comfortably as a man cave.

Am I on the right track with the above or would I be better off using rolls of insulation for the walls?

Have read a lot on the forums about DPM (breathable & non breathable) and also vapor barriers so any advice about which of these I would need would be much appreciated.

 

[Harrier23]

Should have added that I'll probably use loft roll to insulate the roof and would lay this over 12mm plasterboard

 

[^woody^]

Breathable membranes are for timber frames or pitched roofs, not masonry walls. Vapour barrier on the room side behind the plasterboard. Otherwise yes you are on the right track.

 

[Harrier23]

Thanks.

So I would be fine leaving the insulation board uncovered against the exterior wall? Planning on leaving a 25mm air gap between the board and wall.

 

[^woody^]

Normally unless the wall is cavity, you would line it with polythene and fit the insulation flush to it.