Difficult to cast a foundation in an existing house.

[Dr Benz]

Sorry for the late reply. The board is just a mold for the EPS. Then you remove it and the cast concrete slab. You seal the outer wall with lime mortar. This is because concrete does not move, so it cracks more and comes off.

no worries. We have done the same with KC mortar in the foundation wall, and it seems to be really good. Soon it's time for macadam, but water and electricity must be taken care of first.

thanks for clarifying about the board. It felt strange to leave it in the mix so to speak…