That's my shower room plan and cross section through floor.
I am wondering whether to connect the UFH or not.
Looking at how it's gone together, I'm concerned that we've let things slip though lack of control of the process and effectively both drains are coupled to the screed and/or finish tiles.
If we run UFH at 40C and assuming a 10C starting point, the thermal coefficient of expansion of screed is around 0.02mm per m per C -
end result, the screed will expand by about 1-2 mm depending on direction over the full heating cycle.
That's going to try to bend both drain pipes (110 PVC soil pipes) over a height of 50mm so at worst a 1:25 shear (they can flex in the celotex layer).
So I'm wondering if that presents a risk of cracking or weakening the pipes?
Low risk, high impact scenario (the type of scenario I really don't do well with!). Breaking either one of those drains will be a disaster - we lose drainage to one or both bathrooms, boiler and kitchen. Fixing means digging it up.
What do you reckon? Anyone with experience of building UFH into a bathroom?
Losing the UFH will not be a disaster - more of a nice to have.
Cheers - Tim
How did we get here:
Despite best efforts putting foam around the screed perimeter and one drain pipe (the other got overlooked) we've also ended up with the tiles grouted in hard around Drain 1. The tiles stop short of Drain 2 as it's a mess of pipes and will be in the under basin cupboard anyway.
If I was laying the tiles, I would have probably noticed and stopped and left room to silicone. However, this type of tiling exceeds my ability and when you have a tiler whacking them down at full speed, details are hard to manage...
(This was a "chance" UFH zone - we really wanted it for the conservatory, but for other reasons we had to did this 3m2 section of floor out so we chucked some spare pipe in on the offchance).