Insulation in a composite material layer --- need to connect to insulation in vertical wall

[Paopao]

I am using a 3 layers slab with the middle one made of insulation. I need it to connect with the insulation on the mid layer of the vertical wall (the vertical wall is composed of 2 walls one at the bottom and one on top): how can I achieve this?

Thanks
PP

[Paopao]

Idiot me! I didn't stretched the slab to the wall edge