Garden Room Wall Insulation

[Monkeysheed]

Hi all, I've got a timber framed garden room built in the summer and I'm in the process of insulating it. It's a cold roof with composite tiles on the outside, a breathable membrane and then ply. The framing is 100mm timber so I'm planning on leaving a 50mm ventilation gap and then 50mm PIR insulation with vents at the soffits and ridge.

My question is about the wall insulation. The outer layer is 15mm shiplap with a breathable membrane onto 100mm timber. Do the walls need a ventilation gap with vents at the top and bottom like the roof? Or can I just stuff the walls with PIR and not worry about it?

Once the insulations all in I'm planning on another layer of breathable membrane before the final wall covering goes on.

Cheers.

 

[Wayners]

Push the insulation against outside wooden walls.
Treat the walls like a solid single skin brick wall.
That's how I would do it.
Insulation is foil backed so no moisture can get through