Kitchen smells from next door in my loft

[PetseyBear]

Hello. I live in a 1960s semi-detached house. I have a damp problem (on party wall side) which I am trying to resolve. Over Christmas, I had cause to go into the loft. The cooking smells from next door were very strong. If next door has put their kitchen extractor against/through the party wall and not vented externally, could this be causing steam/damp to go into the cavity between the houses and run down onto the shared joist below? (My joist is rotting.) I've got a professional damp proofing company coming out to lift my floor to investigate fully, however, posing the question since smelling their cooking in my loft.
Thanks for any sensible replies.

 

[Wayners]

Yes
If you had cavity wall insulation that may help prevent this