I'm thinking about installing glass block in my old house, in the basement 32x14 and totally pre fabbed and ready to install as is. They do not however come with a frame. At this time there's old hopper aluminum or steel casement windows there. They are totally rusted and cannot be opened or risk not being able to close them. I want to have them ripped them out and glass block windows replace them. I'am assuming the whole frame should be removed. If so, the cement window opening would be the only frame to work with. Should I have my contractor just Martor the windows in as is or have him build a frame that is incerted to the cement that the old frames resided?