Windows present several sources of water. In houses where the heating, ventilation and air conditioning (HVAC) system is oversized, windows are more likely to produce condensate which wet walls in winter. A system that is oversized runs for shorter intervals and is given less time to dehumidify the air and thus is more likely to produce window condensate. Double paned windows produce less condensate than single windows. Wood framed windows usually produce less condensate than aluminum framed windows. Aluminum frames filled with insulation materials will be helpful. Windows should be recessed into the building or under some type overhang which prevents moisture leaks from above.
