An environmentally durable window glass unit is provided with improved edge sealing to protect the interlayer of one or more laminates that make up the unit. The insulated glass unit includes a first pane comprising an outboard glass sheet, an inboard sheet and an interlayer therebetween. The inboard sheet is smaller in length and/or width than the outboard sheet. The glass unit also includes a second pane spaced away from and sealed to the first pane. A gas space is located between the inboard sheet of the first pane and the second pane. A spacer is positioned between the first pane and the second pane. The spacer is adhered to the inboard sheet of the first pane and to the second pane with a primary seal. A second seal adheres the outboard sheet of the first pane to the second pane.