• Hi Jonathon...I appreciate this info. I've been trying to find something that boils down the basics of fire rated walls. Would you mind clearing a few things up? For a 1 hour wall, it would be 5/8" type X (or C) gyp on both sides including double layer walls. The part about it having between 3/4" and 1"  type X gyp is the part that's throwing me off. If you provide 5/8" gyp on both sides then that would be 1 1/4"....which is a 2 hour wall?

• hi angela,
first off good luck on your exams. not an easy process but my feeling is that with a few (10?) “thumbnail” rules you can boils down what would be an otherwise complicated question to a very manageable one and add ten answers to your otherwise excellent results. so that would be the spirit in which this is posted. but “crowd proofing” such a thumbnail is extremely effective.
perhaps someone can jump in here? it may be some days before i can review and post back.
off the top of my head i would say first - that from what i saw it doesn’t matter if it is Type X or type C for the fire ratings as long as you have the thickness. i could be terribly mistaken and maybe someone can clarify. in any case i think you will see an annotation that specifies clearly TYPE X for any fire rated wall - irrespective of this (practical) issue.
so 5/8” “Type X” each side qualifies as 1 hour.
anything that gives you this would include anything /up/ to roughly 1”. 1” each side (type X), 3/4” type X each side. etcetera.
but realistically you will just see:
1/2” each side (unlikely
5/8” each side (possible i guess)
5/8” Type X each side (most likely).
-
2 hour walls would be 1” or /over/. so this would be:
2 - 5/8” Type X each side (not 2 - 5/8” each side AFAIK)
2 - 3/4” Type X each side
2 - 1” Type X each side
1 - 3/4” Type X and 1 - 1/2” Type X (and other combinations).
but you will most likely see:
2 - 5/8” Type X
2 - 1” Type X (with the caveat here that this is more appropriate for a trash chute. the code has a term for these and maybe someone can post the correct term and even a code citation and/or snip from the code so candidates can see it in practice in the IBC?
i would have to check for 1” Type X each side but maybe someone can forum proof this while thread.
anyway, that will need some fine tuning as i think you pointed out a last minute complication i saw in my rule when i was posting this. i have to look closer at 3/4” - 1” and also verify the “Type C versus Type X” issue in regards to fireproofing. my gut says Tyoe X is necessary for either 1 hour or two hour rating within reasonable (or cost effective) thicknesses but for some reason i didn’t see one for some reason. also “categorizing” 3/4” - 1” in the “thumbnail could be beneficial.
anyway, that is a very long-winded answer but i think it is OK to have an open conversation amongst fellow professionals particularly as it relates to boiling down Code Requirements into helpful Thumbnails for professional candidates...
apologies for the typos i’m on my phone and can’t edit the post very efficiently.
maybe david or anton or another code wonk can dive in here...

• (Edited )

i’ve got a sketch i meant to post. i’ll transfer it to my laptop and make this a little easier on the reading. also, i see at least one typo (about type C) but can’t edit it at the moment.

• Hi Angela,

For study purposes and becoming generally familiar with various fire rated assemblies:

Other have suggested this tool as well -- it's great.  Essentially punch in "2-hour wall" and then see how it needs to be constructed in various scenarios.  There is also a button with an associated UL listing to see the nitty gritty of an assembly.

Far more info there than you need for the exam, but generally understand one-hour, two-hour, shaft wall, etc., and where each needs to be used -- same with rated ceilings and floors.

Look into Type X and Type C -- they aren't necessarily interchangeable.  At a basic level, Type X shows up in most UL rated wall assemblies, and Type C is often used on ceilings in the UL listed assemblies.

Good luck!

• Through my experience, a typical 1-hour rated UL 419 wall assembly is 1/2" GWB type 'X', both sides, with sealant top and bottom and metal studs. Wood studs may be a different UL listing. It is the materials mixed in the Type 'X' that give it a rating. Not that a 5/8" by default give a rating. It is the material that is rated that along with the assembly that gives the rating. You can have an 8" CMU wall and not have a rated wall. The CMU needs to be rated to help achieve the rating. Maybe the 5/8" GWB Type 'X' furred out onto the non-rated CMU that would give it a rating. Maybe.

All of these have a cost issue. If you do not need the wall to be rated, than don't spend the money on a rated GWB.

• hey derek.
i’ll try to clarify my drawing and post it. i think it would be nice for s group if us to complet a visual thumbnail.
i find it interesting myself to reduce things to the lowest common denominator but also for other professional candidates i think a visual (“community proofed”) illustration would be welcome.
best
jon

• A visual thumbnail would be great, Jonathan. I think boiling it down to the basics would be really helpful for the exam. I know there are a ton of variations that could be considered, but I doubt NCARB is going to require that we know all of them. If we know enough to answer some basic questions, then I that should be enough.

• i’ll try to come up with something this weekend and post it for proofing. thanks for bumping this and taking a critical look at the same time...