Is the glass broken or cracked?
Is the frame warped or broken?
Is the glass foggy?
Is your energy bill high?
Do you want to reduce noise?
Is cold air coming in during the winter?
Are you renovating a historic home?
Is your window sash rotted or jammed?
Is your glass door sticking in the tread?
Did a ball come through your glass door?
Is water leaking through your skylight?
Do you want to increase your resale value?