Fire Rating Question

[Philarchitect]

Hello,
Our office is constructing an addition above an existing 7-story structure. The existing structure was originally constructed out of module steel boxes with light gauge cold-rolled steel floor, ceiling & wall infill framing. The new floor will be posted up above the existing roof framing. The final assembly will be a combination of new floor & old roof framing.
My question pertains to the proper fire-rated assembly. I have created a detail which should make this a bit more clear. Use the link below to access the detail. Hopefully someone can give me some advice.

Microsoft OneDrive

1drv.ms

 

[Philarchitect]

Hello,
Our office is constructing an addition above an existing 7-story structure. The existing structure was originally constructed out of module steel boxes with light gauge cold-rolled steel floor, ceiling & wall infill framing. The new floor will be posted up above the existing roof framing. The final assembly will be a combination of new floor & old roof framing.
My question pertains to the proper fire-rated assembly. I have created a detail which should make this a bit more clear. Use the link below to access the detail. Hopefully someone can give me some advice.

Microsoft OneDrive

1drv.ms

Update: I forgot to mention that I am looking for a 1-hour fire rating

 

[Paul Sweet]

How are the existing floors fire protected?

Gypsum Association FC-4490 provides 1-hour fire rating. The double layer of 5/8" type X gypsum board provides 1 hour protection for the framing.

 

[Builder Bob]

You may want to look at calculated fire resistance as I don't know that an UL listing exists for the type of construction depicted.

 

[Philarchitect]

How are the existing floors fire protected?

Gypsum Association FC-4490 provides 1-hour fire rating. The double layer of 5/8" type X gypsum board provides 1 hour protection for the framing.

Thank, but unfortunately that assembly contains a plywood subfloor which would not be permitted in the Type-II, non-combustible construction.

 

[steveray]

Like BB said...I think calculated should get you there.....