historical bldg -- adding a shower with a window
I would like to add a shower in a condo that is in a historical building. The only possible location would be in front of a window. Because the building is historical, and neither the facade nor the windows may be changed, I am looking for an alternative from the usual way to waterproof (or attempt to waterproof) a window in a shower area.
The area for the shower is a spacious alcove, so I had an idea for which I would love to hear your comments.
I would build another wall, immediately in front of the exterior wall, with an opening larger than the existing exterior window. The extra wall would provide some additional insulation, and might be handy should any plumbing lines be needed there.
Then I would install a glass shower enclosure, with two doors. The second door (with a high sill, or maybe more like an operable window), when pulled INTO the shower would allow access to the actual exterior window for repairs, cleaning, window treatment, etc. The front of the shower enclosure would be all glass.
I get a funny feeling when I'm about to make a mistake, and I have that feeling now, so I really appreciate your comments -- whatever they are!