I am in the process of buying a an apartment in a high rise building. The apartment has a curtain wall facing south with floor to ceiling windows that appear heavily stained and fogged. The staining can best be described as as a dark brown rust staining and the fog is a general haziness. The rust stains appear in parallel vertical stripes running down the length of the window. As best as I can see there is no moisture inside the window (although I have only been to the apartment a handful of times)

The windows are double pane glass and it appears to me that the issue is on the inside of the outer pane of glass (i.e. between the two panes). From talking to the manager of the building, this problem first was noticed about 10 years ago and has gotten progressively worse. I have been reading everything there is on seal failures and this seems to me (as a novice) to be a potential cause. What I am trying to figure out is

1) Does this sound like the result of a window seal failure - to result in this kind of major discoloration if not treated relatively soon? Or does this problem sound like something else you have encountered

2) Is replacing the window the only solution at this point?

3) If I replace the windows, what is the likelihood that the problem would recur?

4) What do I need to know about this problem / what kind of inspection would be advised before buying the apartment?

If anyone out there can help with my questions, I would be very appreciative.

Here is a link that might be useful: {{!gwi}}