Exterior window unit having adapter sill member

DETAILED DESCRIPTION It is therefore an object of this invention to provide an improved exterior window unit wherein a frame sill can be mounted firmly on a fixed sill in a building wall with maximum ease.
Another object is to provide an adapter sill member for use in combination with exterior window units which member will enable frame sills having increased upper vertical fins to be mounted onto standard fixed sills in the building walls.
According to the invention, there is provided an exterior window unit for covering an opening in a building wall which opening has a first sill.
The exterior window unit comprises a frame having a second sill.
A pair of sashes mounted within the frame in parallel closely spaced planes.
An adapter sill member extends along the length of the first sill, and has a vertical section adapted to be secured to an exterior vertical surface of the first sill, and a horizontal section adapted to be secured to a horizontal top surface of the first sill.
The vertical section has a first engaging means extending along its lower edge.
The second sill has a first mounting means having a vertical portion and a horizontal portion adapted to be secured respectively to the vertical and horizontal sections of the adapter sill member.
The second sill also has a second mounting means having a second engaging means engaging the first engaging means.
Many other addvantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which preferred structural embodiments incorporating the principles of the present invention are shown by way of example.