Insulated stud wall electrics

[hamd01]

Hi guys. After much advice on these forums, I'm well on with a stud wall in our single skin outbuilding.

A couple of images....but I know you guys know what a stud wall looks like

The battens will have 130mm kingspan between them, with a 30mm breather gap to the wall. On top of the battens & insulation ill have a membrain, and then the plasterboard.

Im starting to think abotu where we want switches and sockets, and just wondered what you guys would suggest regards running cable. I guess I dont want the cable behind the kingspan attached to the wall, as that would mean compromising the kingspan. So my options are;

1. Inset the kingspan slightly to create a gap between the kingspan and the pasterboard. Drill holes in the battens and run the cable on top of the kingspan. Would however mean chizzeling out a recess in the kingspan to fit back boxes.

2. Run along the wall, and drill a hole in the kingspan to pull the cable through, also chizzeling out for the back boxes

3. Fasten the cables to the wall, and bring it to the front via a hole in the battens (front to back).

Id also love to know if you would suggest using noggins to fit metal back boxes, or use plastic?

Any suggestions appreciated.

 

[trojanhawrs]

Leave a 15mm gap between plasterboard and insulation and fix 25mm boxes direct to insulation.
I take it they're 95x45 studs? I can't see there being a great deal of benefit in having insulation hanging out the back of the studs, if there's any water ingress there it'll soak your boards and having an air gap round the sides will reduce its effectiveness (i would assume). Because you havent sheeted the back I'd fix battens top and bottom of your cavities on the wall side and 80mm kingspan knocked back to the battens would give your 15mm gap.
Btw, stud walls are made of studs, battens are typically smaller - roofing battens are 50x25