ᐅ Insulation for Concrete Slab XPS – Ursa / Jackodur

Hello,

our house construction project is currently at the stage of building the foundation slab. Regarding the foundation slab—more precisely the XPS insulation—I have a question because I am unsure whether the construction company's execution here is completely correct.

The structure of the foundation slab is basically as follows:
- Gravel layer (natural ground)
- Blinding layer 16/32
- Vapor barrier
- Screed layer approximately 5cm (2 inches)
- 2x 10cm (4 inches) Ursa XPS D N-III-L
- Jackon Jackodur KF 300 used as edge formwork/insulation

I have attached a photo showing at least the current upper layers of the structure.
My question is: should the Jackodur panels (purple) not be extended all the way down to the screed layer?

As the setup currently is, with the Jackodur elements placed on top of the Ursa XPS panels, I wonder if this is the right approach, especially concerning thermal bridging.

Thank you for your feedback.

Since both probably have the same thermal transmittance (U-value), it makes no difference.

I agree. Somehow the materials have to connect, so there will always be a joint. The main thing is that the foundation slab is fully enclosed.

P.S.: Thermal bridge

Thank you both for the feedback!

Hello

Regarding thermal insulation, I don’t see any issues there. But why were different manufacturers used for the board and the sheathing? From my own experience with Jackodur, I know flat panels and sheathing elements that, when wedged and staggered, certainly provide a better connection than the solution shown here.

Olli