An elevation plate or spacer plate is often needed when installing a weatherization fitting on inward opening windows. The thickness of the sash and the distance to the window frame can vary and an elevation plate helps to mount in a neat way. Usually there is a difference of about 5-20 mm and then you need to buy corresponding elevation plates to ensure a good installation.

Elevation washers may also be needed when installing weatherization fittings for outward opening windows. For example, when you have stucco or profiles in the window sash or window sill that do not allow you to mount the weatherization fitting where you want.