Putting external sill saves rendering and processing on the wall outside. The outer sill helps to more efficient water casting as there are factory slope.
Mounted on top of the window frame. When a new external windows sills are built with window. They may be mounted on an existing window. The exterior window sillse is made of aluminum and also in the standard white color is also available in the colors of the catalog on RAL. Also available in different widths, the width of the wall.