Identification of lath and plaster?

[tcox]

I am looking at a building that was constructed in 1952, along the east coast of Florida. Between the ground level and the 2nd level, open web steel joists spaced at approximately two feet center support a concrete floor deck above and a wire lath and plaster ceiling below. I've attached a picture illustrating the system, and have more, if needed. As a result of Hurricane Matthew, the roofing membrane, roof deck and roof framing were missing above this system (i.e., it was exposed to the elements), over a portion of the building, for several months before they were recently replaced.

I was hoping to be able to obtain some additional information about the plaster ceiling (i.e., is it purely cement-based or lime-based, or is there likely some gypsum in the mix as well?). Specifically, is anyone able to determine the type of plaster that may have been used, and the ceiling system's relative resistance to moisture exposure for a period of several months?

Obviously the metal lath cannot hold up to years of moisture exposure. In many instances in the building, plumbing leaks occurred above this ceiling, causing severe corrosion/deterioration of the metal lath and plaster. However, I thought that exposure for only a period of months may not necessarily mean removal/replacement is required.

Thanks.

 

[Ron]

tcox....that appears to be portland cement plaster installed on rib lath. If it were gypsum plaster, it would have a smoother appearance and would be whitish rather than grayish.

Portland cement plaster has been prominent since the 1920's. You can check by trying to crush a bit of the material. PCP will be much stronger than lime or gypsum plaster.