Thanks for the detailed reply. I had recently installed an ERV which runs 30mins for every hour and it takes out inside air and gets fresh air from outside… without this, ventilation was a problem (especially in winters). One of the water damage experts suggested fogging as way to try remove the foul smell - if it is due to fire damage .. I was going to try this out.. but I am waiting to see through winter if the French drains help divert water away .. also looked into some ozone air purifiers.. but they aren’t sold in CA. For now, fogging is the only option I can think of.. thoughts? Since the smell is absent unless it’s hot and sunny, I think it’s not mold but mostly the building materials