Insulation in wall

[regsmyth]

I am building a 2 floor extension, the top floor is more of a mezzanine, so open on two sides to the ground floor. There's a small lobby area on the ground floor, under the mezzanine floor, built as a 100mm stud partition.
In the stud wall there are the ring main cables, there'll also be some central heating pipes.
There are also cables in the mezz floor, generally at about mid joist height.
I'm wondering about insulating the floor and stud wall, for sound insulation primarily (noisy feet upstairs). Would it be normal to pack the stud wall with glass fibre, or could this cause overheating in the cables. Would it be better to use 50mm thick rockwool batts, placed on one side of the cavity only?
And for the floor, same issue. Any thoughts?

 

[Taylortwocities]

I guess your ring final cables go down the stud wall to a socket? I do hope so...

In that case the cable should go against the plasterboard on the side that the socket is located. That way the cable is against the plasterboard. The cable must not go in the middle of the insulation otherwise you must derate the current catrrying capacity of the cable.

 

[regsmyth]

Actually the cables run horizontally between sockets, and so pass through the middle of the studs. Makes the issue of sound insulation a bit awkward, but I guess 50mm batts on one side only could work well enough. The sockets are above worktop height. I suppose I could re-route them vertically (dropping down) and then full fill the cavity, but it's a bit of a waste of cable.... Hmm not sure now!

 

[Pensdown]

You can just pull the insulation clear of the cable where they pass through the studs so that they are in "free air"

By running horizontally and drilling through the middle of the stud, you may have opened up a can of worms regarding safe zones. If the cables are less than 50mm from the surface on the other side of the wall they will need mechanically protecting.

 

[Chri5]

If the cables are less than 50mm from the surface on the other side of the wall they will need mechanically protecting.

Or CU to 17th which allows ADS safety via RCD

 

[regsmyth]

Please translate into English! What's CU and ADS?

I've checked, I've got 50mm clear, as long as I use 12.5mm plasterboard. And a nice thick skim.

All the sockets will be on an RCD circuit too.

 

[regsmyth]

Oops not got this technical wizardry sorted yet....