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Type Ib roof assembly

shellarchitect

looking for a cost effective 1 hour roof assembly.  I’ve been told that there is an approved assembly that using cement board instead of a poured concrete deck but am not having much luck tracking this down.  

Anyone have experience with this or a similar assembly?  This is for a giant factory so cost is the primary concern. 

Thanks!

 
Dec 29, 23 12:02 pm

Don't know that I've seen it done with just cement board before. I think USG's Structo-Crete panels might have some listings but I don't know the details to know what types of structure they've been used with.

Is a cementitious fireproofing like Monokote out of the question? 

Dec 29, 23 1:30 pm  · 
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shellarchitect

Thanks, I’m looking into the USG product now.


Monokote or similar might be what we end up with but is not really preferred.  We want to keep with interior pretty clean.  There is also some concern about the durability of cementitious fireproofing in very humid (Mississippi) areas.

Dec 29, 23 1:54 pm  · 
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gwharton

Cement board doesn't have sufficient rigidity or strength to be roof underlayment. You need something like Densdeck.

Dec 29, 23 4:12 pm  · 
1  · 
curtkram

is this a typical commercial building with steel joist and steel deck?  concrete for a roof deck sounds expensive.  we would typically do spray fireproofing, but i understand you're concerned with the humidity.  is something like UL P562 in the right direction?   https://www.usg.com/content/us...

Dec 30, 23 9:46 am  · 
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curtkram
natematt

That's what I was going to ask. It seems like the best choice for the options depends partly on the type of roof structure you're using, and how you want to finish the interior side of it, because you're going to need something on the inside one way or another, be it some sort of gyp ceiling, or spray applied.

Dec 31, 23 1:10 am  · 
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