[b]Structural Gypsum Roof Panel?[/b] 6

[Einsteim]

Does anybody have information or a source regarding what appears to be a gypsum based structural roof? I visited a building today that has this type of roofing material with wire reinforcing embedded about a 1/3 up from the bottom...it appears to be around 3" thick. They may be prefabricated roofing panels. It spans roughly 1'-9" with embedded purlins. It has some sag that is quite evident. This building is likely 100+ years old. I have attached a picture from the underside.

The contractor wants to place a RTU that will add point loads AWAY from the steel trusses and directly on the gypsum material. I am not going to allow this, but thought maybe somebody would have some information on whatever this is ans some type of allowable loading information.

 

[UcfSE]

Check out / google "gypsum bulb tee" roofs.

link 1

link 2

 

[RARWOOD]

It may be Gypsum fiber concrete.

Do a web search for reinforced gypsum concrete suspension system. Gypsum concrete is calcium sulfate mixed with water.

 

[JRGse]

Try the gypsum association (

http://www.gypsum.org).

I contacted them about gypsum roof decks and I was e-mail a brochure from 1973 for this type of roof deck. It contains properties, load tables etc.
I also uploaded this PDF file to engineer.com (first time I've tried this, let me know if it works).

 

[Einsteim]

This appears to be exactly what we have, thanks so much guys.

 

[JAE]

It looks like a system that uses steel bulb tees spaced out, then a 5/8" gypsum board (or something like that) then a poured gypsum topping.

Or it could be a Tectum board system (

http://www.tectum.com/roofdeck.htm)

The gypsum topping used to have a product called Zonolite (I think) - that had asbestos in it.

Also, here is another thread that is similar to your question:

thread507-84338: Capacity of a gypsum roof

 

[hokie66]

It is not Tectum or Insulrock, the two most common gypsum decks, because they are very fibrous in appearance. I agree that it is gypsum board form on bulb tees with poured gypsum topping.