North facing window: These windows receive less sun than other windows in the home so they tend to condensate more, mold can present itself in the window tracks.

Shower corner and caulk lines

Bathroom fans: Ensure they are working properly as additional humidity can cause mold problems throughout the bathroom.

HVAC systems with humidifiers: Theses system typically require a filter. If unchanged they begin to work like a petri dish growing mold inside your system.

Rain gutters: Check to make sure gutters and clear of debris and remove water at least 6 feet from your home.

Landscaping: Do any areas in your yard slope towards the foundation of your home?

Cold storage areas: These slabs are poured after the foundation and rarely get a good waterproof seal between the wall and the ceilings.

Under sinks: Check cabinet for signs of past leak.

Fan ventilation: do bathroom fans vent outside or just into the attic?

Front loading washing machines: Check rubber membrane for signs of mold.