Once all the pipes had been wrapped in foam and the brackets for the corner beams had been installed…

…the concrete could finally be poured. The great advantage of this method is that the foam glass ballast has a high static load-bearing capacity and is absolutely comparable to conventional strip foundations. And if you now use a concrete with steel reinforcement in it…

…then you can completely dispense with the otherwise necessary laying of the iron armouring. Well, then the lads arrived, and with a few wheelbarrows…

…the stuff was then laid by hand in just under 4 hours.

…by hand because it would have been much more expensive with a hose and flowing concrete.

So now I have an absolutely flat concrete surface, smooth and even like screed, on which I can lay tiles directly. And the whole thing is a compromise given the available options (I would have liked to use 40 cm of foam glass ballast, but the height of the hall was not sufficient for that). The U-value of the floor is therefore not quite as good as I wanted, but at 0.34 W/m²K it is still halfway acceptable.