In message ,
Tricky Dicky writes
On Friday, 31 July 2020 08:20:34 UTC+1, Tricky Dicky wrote:
As part of the kitchen refurbishment I am looking to insulate the
floor which at present is a suspended T&G floor on 100mm joists. I am
looking at fixing 25 X 25 battens to the bottom of the joists and
dropping 75mm foam insulation in between the joists. Any advice
regards preferences between Kingspan or Celutex or is it just a case
of whichever I can get at the best price?

Richard

After a bit of research Celotex( note correct spelling) is out with a
P/A ratio of 0.7 and a resultant maximum U-value of 0.24 to comply with
Part L, the only products they had were 100mm and 110mm thick and would
cause some difficulties since my joists are 4" deep.

So it's Kingspan, again two products Kooltherm 103 which I would need a
90mm thickness or the higher performing Thermafloor T70 where a 75mm
thickness will give me a u-value of 0.22. Using the T70 allows me to
use my preferred method of supporting the panels using 25X25 battens.

Back to my circular saw proposal. Having produced your 400/600mm wide
slabs, you could easily rebate the sides to accept your battens and use
what I suspect will be much cheaper and more available Kingspan/Celotex.
Now we are all used to wearing face masks, you can do the job on the
lawn:-)

Now just need to phone around and get some prices. I have tried to get
some online but most of the insulation stockists seem to want you to
send in your quote and then give a price plus you can only buy them in
batches usually 3 or 4 boards and of course Sods Law I only need 3.
Might try a few local builders merchants who I have seen stocking foam
insulation but suspect they may not have extensive varieties so it will
be pot luck. Anyway just thought I would pass on my findings for anyone
else contemplating doing the same.

Richard

--
Tim Lamb