Sockets in PIR backed plasterboard?

[CaptainJack88]

We have a scenario whereby the house has a single skin brick wall, however we need to fit sockets to this wall.

We're looking at an insulated plasterboard such as Celotex PL4025 which has a vapour barrier backer on it.

What's the best way to go about mounting a backbox and cables?

• Conduit on the brick with cables inside it and cut into the insulation board (this cuts through the vapour barrier though
• Backboxes screwed to the brick and a hole cut? Also cuts through the vapour barrier

 

[JP_]

I cut through insulation but then used insulation tape to put the vapour barrier back. I had 50mm kingspan to play with though so did not go all the way through the insulation to the wall (I cut all out and put 25mm back, 35mm box) .

 

[JohnD]

you could use a 20mm insulating board on the wall, with the conduits cut into it, then your main insulating board on top, without cuts. But you would always need holes in it for the sockets. The conduit is useful, because it makes it easy to make later additions or alterations.

I don't know a way to put sockets in internal wall insulation without holes. There might be a liner or a way of taping them., or you could have a membrane behind the boxes, screwing them to the wall through your first layer of insulation.

 

[phatboy]

Cutting in a hole may well cause a cold-spot, and so damp could be attracted there - far from ideal!

How about 25mm Celotex, then some 2x1 timber over it to create a service void, and then plasterboard? You will be able to fit a 35mm dry lining box in 12.5mm plasterboard.

But, 25mm isn't very much insulation.....