Hi,

I've been reading the various posts over the years on wet UFH, which I
am having installed in a new extension in a few weeks time. I have a
few questions ...

1. I am unsure about the flooring to lay on top. Part of the new build
is an extension of the existing lounge. I want the screed above the
pipes to be flush with the suspended floorboards of the old part of
the house so that I can fit my new super-large lounge with the same
flooring throughout, for continuity. I am thinking of some Kahrs 10mm
Linnea 1-strip engineered flooring (which apparently they have just
started to make), because presumably the conductivity of the heat will
be better through this than the 15mm version, but it will be more
hardwearing than the 7mm version. My worry is this: it will be sitting
on two very different surfaces and so will respond differently in
terms of expansion, warping, wear etc because the old half is
floorboards + rads, the new half is concrete + UFH. Is it unwise to do
this? Should I consider the orientation of the new flooring as well? I
want to lay along the length of the room, which will also be
perpendicular to the old floorboards. This means that each run of the
flooring will go across the join between old and new. [Does this make
sense?!]

2. In the kitchen, presumably you don't lay the pipes under the part
of the kitchen where the units are going to sit. Does this mean you
should decrease the spacing of the pipes so that the total length is
equivalent to having laid across the entire floor?

3. Given the depth of the concrete slab that the builder has already
poured in, I reckon I have room for about 100mm of celotex/kingspan
boards leaving 65mm for the pipes & screed and 10mm for the flooring.
Do these sound reasonable thicknesses?

I am keen to look at flooring before buying (I'm in the Cambridge
area) so if you think I am mad going for the Kahrs, let me know
something else that mainstream shops might have in stock!

Thanks for any advice,
Lotty.