Double insulation below and above the floor slab?

But maybe the thread creator will say something about it

The creator says the following about it: The sense and nonsense of KfW standards should actually not be the topic of this thread. I wanted to find out whether a second insulation makes sense or if it is pointless. For me, it is simply redundant – if the perimeter insulation is not sufficiently dimensioned, then I just make it thicker and do not start another insulation layer 20 cm higher up. That is my way of thinking – but maybe it is completely wrong – that is why I would simply like to hear the opinion of an expert.

If the insulation is placed under the bopa, it is within the thermal envelope, so it is not a thermal bridge. And on the bopa, you need it anyway because of the underfloor heating!

An expert can gladly explain this to you in more detail, etc. Have a nice evening.

One insulation is against the ground. The other ensures that the underfloor heating does not only heat the floor slab. 2 different functions

okay, thanks a lot for the explanation - that somehow makes sense - although I wonder what happens with the underfloor heating systems that are directly embedded in the floor slab... they work too, right?

I believe it is called Schwedeplatte, I have only heard negative things about it.