Leaking windows can be caused by several problems, but usually a dual-pane window that leaks has a manufacturing defect such as an incorrect seal. Contact the manufacturer of the windows if the leak starts within the warranty time, or check around the window for any signs of damage to the seal.
Adding or fixing screens on windows is usually not a difficult task and simple for the home owner to complete. Ensure that the screens you are using are flat and not warped and that the screens are not torn or damaged before installation. New screening material can be found at most hardware stores and is simple to replace.
Double and triple pane windows or specialized types of energy saving windows may need to be installed by a contractor to maintain the warranty on the window. Always carefully check the manufacturers warranty for exceptions that may invalidate the warranty on the windows.
