I’m in an 1160 square foot half-duplex built in 1999. It is two stories, plus the basement. There is a legal walkout suite in the basement. Suite was built and finished at the same time as the house.
The main part of the house is heated with forced air. (No air conditioning, I live in the Rockies)
The basement has in-slab heating.
I never noticed anything in the first few years, but for the last few years, I can smell what the tenants are cooking. I’m pretty sure it is coming through my cold-air return vents, particularly on the top floor. This happens regardless of whether they use the exhaust fan over the stove (which is vented outside)
Noise isn’t an issue at all – I never hear my next door neighbors nor my tenants. Smell, however, is an issue – and I think I’d rather hear my tenants than smell them!!
What might be happening?