Cavity insulation round new French Door

[James1979]

I’ve just converted a window to French door but not sure what (if anything) should go in cavity at the bottom of the door?

I’ve filled the cavity at the side with rock wool slabs before skimming the wall and installing the cloaking but the bottom of the door is in line with the DPC so didn’t know if putting insulation in the bottom cavity would bridge it and potentially cause damp?

There’s a wooden threshold going inside if that makes a difference.

photo with area outlined in red...

 

[Mr Chibs]

I'd either fill with expanding foam, over a few goes, or celotex board applied to the inner skin (with expanding foam) that way you can leave an air gap on the outer skin.

 

[crank39]

Cavity closer