Mounting socket/patress box in thick insulated plasterboard

[jrcarey]

I have D&D insulated plasterboard onto a brick wall.
I am installing a socket.
The board has a 25mm backing insulation layer.
Will the lugs on a patress box engage into the insulation OK - maybe with help from some expanding foam?
Any suggestions gratefully received.

[stoneyboy]

jrcarey,
Cut the hole so it is just big enough for the dry lining box, pust the lugs into the insulation so they grip on the back of the plasterboard.
end

[jrcarey]

Stoneyboy -
thankyou for confirming I dont need extra support from foam - I dont like the stuff!!