Lapping DPM onto existing DPC

[finster]

Hi all,

Quick question - I am converting my garage and my BCO has suggested that an acceptable floor would be: -

• 
  * DPM lapped to DPC straight on existing concrete base
  * At least 70mm PIR insulation
  * Another DPM lapped to DPC
  * Moisture resistant 18mm chipboard (floating floor)

This all seems fine to me, but what's the best way to "lap" the DPM with the DPC - does this mean just overlap up the wall past the chipboard, or bed into the mortar in the wall?

What's the usual way to do this? I'm a bit wary of damaging the DPC with the second option...

Thanks in advance...