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Polystyrene walls in IIB construction?

steveray

steveray

SAWHORSE
Joined
Nov 25, 2009
Messages
13,732
Location
West of the river CT
First post from my phone....This doesn't seem right to me but..

Interior non bearing office partitions are made of a sandwich panel polystyrene core with 1/2 gypsum on both sides.
Foam ( near as I know) has never been tested to ASTM136 per 703.5

Foam plastic is allowed exception #3 in 603.1.
Foam plastic is allowed where it is separated by 1/2 gypsum in Chapter 26..

Having a hard time believing we could build a IIB building out of SIPs if they were covered in gypsum... Insight?

Thanks!
 
Thanks Ty.....I don't think we came to a definitive conclusion there although I have become a little more questioning in the last 8 years.....I see the crux of the question now being: Does foam get a blanket pass, (structural or non) where non-combustible is required, if it is separated/covered in drywall....?

Seems odd that we can't build nonbearing walls out of non-FRT wood, but we can build them out of foam.....(and yes, I know there is at least one exception for non FRTW framing in 603)...;)
 
I found the older thread a bit unresolved as well, but figured I would throw it out there.

I do not think that it should get a blanket pass either, but it is hard to reject it when you can site build the wall (steel stud, gyp.) with rigid foam insulation. Not sure how that differs significantly from a fire perspective then a SIP panel with foam and adhered gyp.


As an alternative, there are also a number of manufacturers that produce mineral wool insulated metal panels (IMPs). I was introduced to these for the first time recently, and the IMP wall even achieved a 2-hr fire resistance rating. Was utilized as a fire barrier to reduce the fire area and provide separation between uses (B/S-1). Was honestly one of the easiest fire barrier installs that I've seen.
 
steveray said:
First post from my phone....This doesn't seem right to me but..

Interior non bearing office partitions are made of a sandwich panel polystyrene core with 1/2 gypsum on both sides.
Foam ( near as I know) has never been tested to ASTM136 per 703.5

Foam plastic is allowed exception #3 in 603.1.
Foam plastic is allowed where it is separated by 1/2 gypsum in Chapter 26..

Having a hard time believing we could build a IIB building out of SIPs if they were covered in gypsum... Insight?

Thanks!
Click to expand...

It's hard to believe if we only focus on individual components. The key here is to see it as an assembly and if it was actually tested as an assembly with regard to how it reacts to fire. Specifically, has it been tested per ASTM E 119? Is there a UL design number associated with such an assembly? Ask the manufacturer for information on it.
 
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