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

"Christian McArdle" wrote in message
.net...

My problem is that the current 'slab' height means that it will
be impossible to raise the floor by any more than 100mm.. So,
If I have to add 50mm of insulation and 75mm of screed, the only
physically way possible would be to lower the slab by 25mm, and
as you will imagine, this impossible.

Well, 25mm of insulation would be infinitely better than none. That
would
allow 75mm of screed.

Christian.


Interesting.. I just spoke to my local(ish) supplier of insulation and
they can supply 40mm boards.. This will give me 60mm of screed, and if
I follow the next posters advise of using chicken wire as re-enforcing
material, its should give me a base which is still strong enough.

With regards to installation, is it as simple as cutting it to shape
and placing it on the floor (ontop of the DPC) before they lay the
screed? Should it go right upto the wall, or should I leave a gap??

I was surprised how much the insulation costs though (£16+vat for
1.2x24m boards).. I will make some enquiries over the next few days.


Make sure you are gettng polystrne foam - blue or pink generally - not
Cleotex. That price sounds about right for a 5 pack of 4x2 shhets.


Not correct ..... you want floor grade polyuretane not polystyrene ... it
has about twice the insulant value of polystyrene.

Jon has limited depth - and therfore to get max insulation with minium depth
he should most defionietly go for Poyurethane.

I buy mine from Seconds & Co. http://www.secondsandco.co.uk/

Recently bought 140 m2 of 50mm polyurethane ... and 124m2 of foil faced
100mm polyurethane. Most of what they supplied was Kingspan product.


Just slap it down, and you may, if its a huge area, want to lay some up
the sides of the screed as well to allow for expansion,

Vertical insulation is important if heating the floor - but if no floor
heating agree you can leave it out - and on your size slab it is not really
needed for expansion.


Rick