Rather than high jacking the *pipe* thread.
My architect has opted for internal (70mm Celotex) topped with 12mm pb on 150mm block work.
How should any electrical cabling be run?
I suppose there will be a gap at the back, as the wall stands close to another building, but this doesn't feel very professional:-)
regards
Cables go behind the plasterboard and get drylined over. No trunking, capping or anything else
Building work isn't 'very professional'
First lesson I learnt. 'Stop thinking like an engineer, and measuring tolerances in mm, we do tolerances in feet' ;-)
If you are studding the wall, stop when the studs are in, and do first fix plumbing and electrical and simply tack the cables to the block work.
Then insulate and board uup, leaving holes with cables banging out for second fix, and use plastic back boxes, or, mount metal boxes on block work and curl cables inside before boarding up. You can apply board, see where a mark is left, and cut out the holes as as you go..
Oh! I have never seen *dot and dab* plasterboard work and assumed there would be too little space for cables.
I suppose laying flat from a new roll helps.
regards
>
Er. no. This is solid block with exterior battens and feather edge boarding. The bit using 220mm block I had considered using skirting trunking but this may not comply with height regs. and tends to be a bit bulky. I suppose chasing the blocks is the alternative.
Umm.. Fixings must be tricky: 70mm Celotex, 12mm + dabs for plasterboard. Lo-ong screws!
regards
Tim Lamb coughed up some electrons that declared:
I've pulled Cat5e behind already fixed dot'n'dab - but for short runs, had to cut a few small openings to grab, pull and rethread cable and it was a right *****.
Cheers
Tim
What's a backing box depth - about 40mm? so another 40 to pack out? make up some platters of MDF that thick..and glue to wall!
Are you really dot and dabbing over celotex? seems nasty to me.
I've no idea if this is the "correct" approach, but why not fix 15mm battening (with suitable gaps) to the wall (screw or powernail), first fix your cables, and then dot&dab onto the battening?
If not that, try manufacturers data here:
In message , RubberBiker writes
In message , The Natural Philosopher writes
The Celotex site only seems to offer battened options so you are probably correct.
regards
From the point of view of controlling the cable temperature (important on power circuits), you want at least one side of the cable in contact with a conductive surface. So either clipped against the masonry (or under capping), and on top of the insulation (in a notch) against the plasterboard.
I wonder what happens if someone has their cable above the insulation and then tops it up? The rules state derate by 50%. Won't help much if someone then puts a couple of enclosed ceiling lights up as both ends of the cable will be hot so there is nowhere to conduct any heat out of the cable.
Indeed. This is often the case when people add loft insulation. Normally lighting circuits are so over specced anyway that it does not make any difference there, but on a more heavily loaded power circuit you can rapidly run out of thermal headroom and / or fall below the minimum required current carrying capacity for a leg of a ring circuit.
I am just hoping to get a loose grasp of how these things are done now.
Having just parted company with the original potential builder (disagreement as to what was included in the quote) I am trying to understand the order of events around first fix/insulation/plastering time.
Celotex advocate battens to secure their insulation and provide a fixing for plaster board so I suppose correctly rated cables can be run in the voids.
I may end up with cavity work anyway.
regards
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