# Wood & Steel Fireproofing



## wildleg (Apr 12, 2009)

Wood/Steel bldgs usually only had critical structure items protected (stairwell/elevator shaft supports), and the rest were only protected by sprinkler system. but wtf do I know - that's someone else's bag o worms


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## don_resqcapt19 (Jul 18, 2010)

Steel loses over 50% of its strength at about 1100°F. That temperature can be reached rapidly in a fire. Wood only loses its structural strength as it burns. The rule of thumb is that wood burns about 1" of thickness per hour. You have a lot longer time before the fire causes a collapse in a wood structure as compared to unprotected steel. Note, I am talking about solid word structures, not trusses, engineered joists or other light weight wood construction. The light weight wood structures fail even quicker than unprotected steel.


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## Grounded-B (Jan 5, 2011)

Big John said:


> Remodeling an existing building of mostly wood construction, the architect had all the steel beams and columns fireproofed, but none of the wooden ones.
> 
> I was told that the steel will in fact fail before the wood if not protected. Is that correct?
> 
> ...


You were told correctly.

Steel will twist and fail in a fire. Wood timbers will char and in a way, self-insulate themselves for a while.


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## erics37 (May 7, 2009)

We did a hospital emergency room remodel a few years ago, they wrapped the steel posts and stuff with 4 layers of sheetrock :blink:


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## Big John (May 23, 2010)

Interesting, thanks, gentlemen. I looked through NFPA for a general fireproofing reference and couldn't find anything. Anyone have any ideas?

Eric, I did a parking garage underneath some apartments where the ceiling was also 4 layers of sheetrock. I think that's how they get their two hour rating.

-John


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## jmsmith (Sep 10, 2011)

John--
I haven't checked, but you may find that info in the International Building Code. I do know that they have the regs on structural loading on steel framing and other structures. Hope this helps.
-Jim


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## BBQ (Nov 16, 2010)

Big John said:


> Interesting, thanks, gentlemen. I looked through NFPA for a general fireproofing reference and couldn't find anything. Anyone have any ideas?


The building codes hold the rules for fire resistance and the UL 'Orange Book' contains the assemblies to achieve the ratings.


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