Sub floor in kitchen

[cdbe]

I did:
Hardcore,
Blinding sand,
DPM,
Insulation with taped joints,
Concrete.

I couldn't face digging out even more clay or paying for a screed as well as concrete for our extension. While the concrete isn't the final floor finish we managed to get the slab level with a deviation of less than 10mm over 5.5 X 6m and a bit if self leveling will take care of the rest. There is the point about the insulation being a long way down and not doing much but we're having a big woodburner so hopefully the slab will act as a thermal store.

 

[mordzy]

@cbde. Yeh thats my prob. the dig at the beginning. The room is only 5x4m there was no insulation on the floor I dug out, just a tiled slab on dirt. it got really cold. I figured blocking the loss of the heat to ground and the cold coming back up would be much better than it was. Ive also thought about running some UFH pipes through the slab for good measure.

Whats the best way to stick the DPM in. Its an old stone house so doesnt have one at the moment. do I have to rake out the mortar all the way round the room to slide in a DPM and lap/tape that to the visqueen sheeting below the slab?