Annual inspections should also examine the operation of each window. Window inspection programs will help to identify maintenance needs. Those needs will depend on the materials used in the construction of the window. For wooden windows, the single largest maintenance expense is painting. On the average, wooden windows must be repainted every four to five years.
Painting is also a significant expense for steel windows.
Depending on the environment, steel windows may require repainting every five to 10 years to avoid corrosion. Problems with corrosion have led to the replacement of steel windows with ones made from aluminum or vinyl. Another maintenance expense common to all windows is caulking. Caulking is used to seal the gap between the window and the wall in which it is installed. If the caulking deteriorates, water can enter the space, resulting in damage to the window itself and to wall materials.