If the space is empty, regardless of the season, turn on the heat. Assuming that the mold has been removed by correct means, you need to eliminate the dampness from the area. If no heat available, try a space heater while you are in the space, to avoid accidental fires…
You can also try Lysol or Febreeze while removing the dampness.
Hire a mold remediation company with an IR camera and moisture reading tools… find the Cold, WET spots.
— Figure out where plumbing lines are likely hidden and may have leaked…
— is water coming in through basement walls that weren’t properly prepared?
— is there a condensation problem, maybe with the HVAC system?
— Do you have HVAC in the attic and the condensation line might have overflowed?
— Did an animal die somewhere inside?
— do you suspect any roof problems, door or window flashing issues?
Find the soft spots and start ripping out drywall. The cause will become obvious if you carefully think through the problem at hand.
