What Product to Seal Outer Wall to Stop Wet Patches on Internal Cavity Wall?

[DIYJC]

I am getting wet patches on my internal wall of a cavity wall when wind/rain is blowing in a particular direction. The cavity has been filled with insulation at some point; I have removed a brick from the outside wall and the insulation feels dry but the back of the bricks on the outside wall were wet. Reading through previous posts I understand water is being transferred across the cavity via the wall ties. A tradesman said he had sealed the wall but I'm not so sure he has or maybe not applied enough. For my own piece of mind I thought I would attempt to seal the wall again.
Can anyone advise on what to use and how to apply it?

[welsh brickie]

try aquaseal a silicone based product that can be applied with a brush or spraygun

[thedoctor]

Repoint the wall properly. If its the bricks themselves that are too porous then Welsh Brickie is right and you should try ths Thompsons Water seal https://www.diydoctor.org.uk/DIY-superst ... litre.html