The Barriar does not have the reinforcing webbing that the Intello has, but it still seems pretty strong.
Another plus for the Barriair is that it has a built in double sided air tightness tape along the length of a roll, so that saves a lot of air tightness tape.
I only found out about the Barriar from another local self builder who is using it. I got it from Jewson's but it has to be ordered.
Ok, but if i do go for a 450mm void do you think i could build the outer leaf ok ? Working in that gap.
If i can't manage to do this can you mix the insulation types up. So do this wall with the soft insulation and the rest with rigid ?
Rigid board insulation systems don't work in this scenario,where you have to build the outer leaf first. The insulation is pinned back to the inner leaf to allow a ventilation void-this is just impossible when the outer leaf is built first,as it would be in your situation.