Threshold screed detail

[Bill M]

Anyone know the accepted way of dealing with screeding over the cavity to the door frame?

I've posted a picture:

inner leaf is at the same level as the bottom of the door frame. The screed is to be 50 mm thick.

I suppose a galvenised steel L shaped tray screwed to the door frame and resting on the inner leaf might be one way, but is there a simple everyday widget/technique?

TIA

Bill M

[Mike Taylor]

bed some slate over the DPC and cavity then screed on top

50mm is considered too thin these days most specify 65mm or over