Originally Posted by
Jeff Euriech
How would R602.8 apply to a steel framed house? From inside the attic I could look down into a wall cavity?
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Jeff,
With steel frame construction it would depend on the installation aspect, such as: (from the 2006 IRC)
-> R1001.12 Fireplace fireblocking.Fireplace fireblocking shall comply with the provisions of Section R602.8.
-> M1801.9 Fireblocking.Vent and chimney installations shall be fireblocked in accordance with Section R602.8.
-> G2425.15.4 (501.15.4) Clearances. Chimneys and vents shall have airspace clearance to combustibles in accordance with Chapter 10 and the chimney or vent manufacturer’s installation instructions. Noncombustible firestopping or fireblocking shall be provided in accordance with Chapter 10.
However, each of the above could be argued that they are applicable to combustible construction only.
In South Florida where we used steel framing for non-load bearing interior walls, we also used wood trusses, which put us back into the protection of combustible material, however, in your photo you are also using steel trusses, but ... you still have OSB roof sheathing to protect (unless it is fire retardant treated).
What we always used for that draftstopping was 1/2" gypsum board as that is all that is required when a draftstop is installed in a floor/ceiling area or in an attic. In steel construction the draftstopping is there to seal off the concealed spaces from allowing them to generate drafts which could lead to the spread of smoke and fire.
In steel framing the term changes from fireblocking to draftstopping, and I am at a loss right now to find a reference to it for that use in the IRC.
Logic and common sense tells you you need at least draftstopping at concealed spaces where the vertical concealed spaces intersect with horizontal concealed spaces, and vice versa.
Ever tried to ignite the paper on the back of gypsum board? I have, with a MAP gas torch even, and, sure, I could get the paper to flame up and burn ... as long as I held the torch on it, but as soon as I removed the torch the flames stopped. I ended up with a 6" square piece of gypsum board with the paper charred, but the charred remains were still on the back of the gypsum board. In a case like that, I would not be concerned about the gypsum board paper burning, I would be concerned as to why there was a MAP gas torch lit and inside my walls. 