Mold around windows and on ceilings is typically caused by excess moisture in those areas. Improperly sealed windows, water leaks and a faulty HVAC system are common causes of excess moisture.
Poorly insulated windows and condensation on windows can lead to mold growth indoors. To remedy this problem, seal windows with caulking, and wipe away condensation frequently throughout the day. Installing energy-efficient windows reduces condensation and prevents mold around windows, as properly fitted windows prevents air leaks and lowers humidity.
Mold on the ceiling is often the result of a leak in the roof or faulty plumbing. Inspect the roof and plumbing for signs of damage, and repair damaged roofs and plumbing to prevent mold growth. In homes with an improperly sized HVAC unit, mold may develop as a result of poor airflow.
Hire a professional to determine whether the HVAC unit is the proper size for the home and to ensure that the home's ventilation system is adequate. Kitchens and bathrooms may need additional ventilation directly to outside air. Air leaks in ducts can also lead to mold growth from increased humidity. If the HVAC unit is properly sized, inspect the ducts for air leaks and repair them if necessary.