Attics

Various things can occur in an attic that can contribute to mold growth.

Defects that effect the performance of the attics passive ventilation (air flow) 
allowing for increased humidity levels.

Mechanical ventilation systems.
Gas appliances (water heater, furnace)
Bathroom exhaust fans

Roof penetrations

During a Moisture Intrusion Inspection all aspects of the attic structure and its components are inspected to identify potential failures.
Attics are dynamic and allow for air to transfer between this area and the interior living space.