load bearing storefront window wall

[Prestressed Guy]

Anyone know anything about a load bearing storefront window system. [built in the 1950's]

I looked at a residence yesterday which was built in the 50's that has a 20' aluminum storefront type window wall. The window also returns about 5' around the corner of the building which has a conventionally framed hip roof so both of these walls carry the roof load. The mullions and corner post are all aluminum less than 2" of total width. All storefront windows that I have worked with are non-load bearing but this one is the only vertical structure that can carry the roof load.

 

[phamENG]

The mullions are carrying the load. They can do it just fine, at least under typical gravity loads. Whether or not it's all tied in properly for uplift off that water is another question. And as a hip roof, the actual load on each wall is probably pretty minimal. Of course, I can't see the dimensions or roof slope or anything else, so it's hard to say.

 

[Prestressed Guy]

That was my conclusion as well. It IS load bearing whether it was engineered by the manufacturer for that purpose or not. It has passed 70 some years of load testing so it obviously can do the job.
The windows have never been replaced since it was built per the previous owner [2nd] who inherited it from his father who had it built. Decent provenance.
The new owner wants to change a couple of the bays into a sliding door to allow access to a new deck. Two of the mullions have a noticeably different constructions [narrower] so it might be possible to remove one of those narrow mullions. I am inclined to say that this should not be done unless it is found that these mullions have a deflection head gap at the top that would mean that the mullion is not carrying load.
They are beginning to do some demolition of the interior finishes to see what is in the head space over the windows.