Exterior window unit having adapter sill plate

摘要

An exterior window unit is adapted to cover an opening in a building wall. A frame sill of the unit has a mounting fin secured to a fixed sill in the building wall and having a first flange. An adapter sill plate is placed on and secured to the top surface of the fixed sill. The adapter sill plate has at its outer marginal edge a second flange which interfits with the first flange.