Gonna be chopping out a window, putting in some upvc french doors and running 25mm insulation with wooden flooring in to the frame internally at the threshold.

The wall is typical cavity construction (102/75/100) and the door frame is fixing to the outer skin. The internal floor slab has no DPM under it (there will however be one between the UFH and the wooden flooring)

I gonna sit the frame on a DPC but what happens about the open cavity at the threshold as the wooden flooring is to run over it?

Do I concrete it up level with the DPC, but wont that cause damp probs with bridging the cavity?

Or do I somehow lap on to the DPC a piece of DPM, down the void and up the otherside then concrete fill the cavity?