Pour concrete on existing floor

[babyem91]

Hello

I am considering casting a new concrete slab (10cm) on an existing old concrete floor (15 cm thick). The existing concrete floor has no reinforcement, just lots of stones of various sizes.

The purpose of the casting is partly to stabilize/get a more stable floor as it is a bit shaky in some areas, and partly because we need to level up.

I don't want the new cast to become an extra "weight" on the existing one but for them to become like one new strong slab instead.

Does anyone have tips on how we should do it?

The builders plan to do it as follows:
Existing concrete floor (15cm) - foam (5cm) - reinforcement mesh - underfloor heating - cast new concrete (10cm) - levelling compound.

Will it become like one new compact slab or just a weight on the existing one? I'm thinking about how the foam covers all surfaces and concrete struggles to become a slab?

Alternative

Existing concrete floor (15cm) - reinforcement mesh - cast new concrete (5cm) - foam (5cm) - underfloor heating - levelling compound

Does this alternative require more levelling compound, leading to additional cost?

The area is 80sqm

Thanks

 

[prototypen]

What is that space? 50 mm foam and underfloor heating don't sound economical.
If the existing floor is not stable, there might be voids underneath, and then it won't be completely good.

Why not just shovel out the old floor.

Protte

 

[babyem91]

It is the entrance level, living room & kitchen.

It will require significantly more work if we need to remove the existing one, and we would also need double concrete to reach the correct level/height.

 

[prototypen]

There will be 200 mm of foam plastic and the same amount of new concrete. Today's houses are built on 300 mm of foam plastic.