Rusty_Nutz

Hi Build Hub, Carrying out a rear extension on our detached 1960's house in Surrey. In need of a bit of advice or guidance regarding the possible need for damp proofing to an existing external wall that now becomes an internal wall after an extension. I plan to keep it as exposed brickwork as attached visual. The problem (or maybe it's not a problem) I have is the new extension lower floor level (blue line) is a lot lower then the existing DPC (pink line). Is there a chance moisture will run up that external wall and create damp issues? If so, what would be my best course of action? Do I treat it like a basement and tank the wall? Hoping that all made sense. Many thanks in advance.