Steel Stud Fire Resistence- Horiz. 2

[concowby]

I have a situation where 18 gauge 2x6" steel studs have been used as ceiling joists with 5/8" type 'X' gyp. bd. both sides. I am unable to find a verifiable hourly rating for this assembly. UL only has floor or roof assemblies. Is there any web sites, or printed info. regarding such an assembly? Even info. on the fire testing of steel in a horizontal application would be helpful. Any info. is greatly appreciated.

 

[ishvaaag]

A single gypsum board >1.3 cm thick is rated 3 hours with a single face exposed and with 3 faces (of a double tee) exposed 30 mins for members with depth less than 140 mm, and 1 hour for members with depth bigger than 160 mm. This puts the protection for a single gypsum board with your 150 mm depth around 45 mins. Since only 1 face protects the stud-joists, and the failure of such stud joists would ruin the opposite face, only 45 mins looks warranted.

Source is Table 1.9 in NBE CPI-91, a past spanish code for fire protection.

 

[concowby]

Thank you for your information. Unfortunately, the gypsum by itself does not provide the official hourly rating. Mainly because this is a horizontal assembly. If I can prove that the steel, by itself or in a tested situation, can stand- then i have something.

 

[ERV]

Here is an excellent reference for fire resistive design and code requirements:

http://www.iccsafe.org/e/prodlist.h...njObEgvya5443|27&words=084s2k1&go.x=20&go.y=6