The Natural Philosopher wrote in message ...
Jon Weaver wrote:

Where would the insulation layer go, ontop, or under the DPM?


AIUI, on top of the DPM. Someone more knowledgable than me will suggest the
exact ordering and thicknesses. However, I suspect 50mm of Jablite would
make a real difference, and 30mm of screed might work on top to make the
original thickness.

Christian.




Actually it makes sod all difference where the DPM goes. Above or below
the insulation. I asked teh architecet, and he just shrugged.

I put mine ABOVE for the imple practical reason that it wouldnt get
puntured on teh rather rough surface underneath - the insulation is very
good as covering sharp lumps

50mm blue/pink foam is excellent. 75mm is even better. At LEAST 75mm
screed, and more if you can fit it in.


This whole issue of insulation re-opens a can of worms already
discussed in the following thread:

http://groups.google.com/groups?hl=e...ogle.com#link1

Basically, the problem here was that I was planning to install my ring
main into the cavity, which contained insulation.

It seems that 2.5mm cable surrounded by insulation is not able to
carry the current required for a 32A ring main.

The solution to this was to simply no add the insulation into the
cavity.

However, in order to get the cable from the cavity, to a suitable
point behind a socket to gain access to the existing ring, I have run
the cables under the dwarf wall and along the slab for around 8-10".
This is protected by some metal capping and I intended to lay the DPC
and screed directly on top.

However, if I am now going to be adding some insulation, then I will
be back to square one, as the Electrical regs state that an 2.5mm
cable surrounded in insluation is not suitable for a 32A ring main.

I can't seem to win here!.

Can anyone comment on this? Bearing in mind that the lengh of the
inslated cable is less than 10", is it really a concern? I guess that
a consideration is that the insluation won't be 'surrounding' the
cable, instead it will simply be on top... A crude cross section of
the installation is as follows:

----------------
Ceramic Tiles
----------------
Adhesive
----------------

Screed

----------------

Insulation

----------------
++++++++++++++++ DPC
~~~~~~~~~~~~~~~~ Metal Capping
================ 2.5mm Cables (Layed side by side)
----------------


Concrete


----------------


Why not lay them in the screed then?

Good point.. I suppose I could, however, I have already installed the
metal capping.. It would mean ripping it all up and messinging about
with it, whilst the builder is trying to work.

Thinking about it, I don't think that it would do any harm, to leave
the cable un-covered.. The area in question would only be 100x400mm
and I don't really think that this would affect the efficiency of the
insulation.