I have this extension to an existing wall which has been been really poorly pointed at the join and I have no idea how the two walls have been tied in. I'm getting a lot of damp on the existing section of wall that joins this new extension. You can see from the pics the pointing between the two walls is all cracked. It looks like some hard mastic as opposed to a mortar mix.
How do I create a water tight seal between the two walls. Do I just rake out this material and point it with a mortar mix (what ratio) or do I need to do something else?
Any advise appreciated.
How do I create a water tight seal between the two walls. Do I just rake out this material and point it with a mortar mix (what ratio) or do I need to do something else?
Any advise appreciated.

