three places:

first place I'd look is the UL book under ceiling assemblies.

second - the manufacturer might have some info on fire-rating... if the product you spec'd doesn't, find someone else who does.

if those don't turn up anything - check the building code - if where you are uses the current version of IBC as a base, there is a matrix for ratings bases on materials...

good luck.

be careful. i'm not sure about the rating, but if you are protecting foam, you can only do this at the roof in the irc. you can't protect foam with t&g ceiling if it is in floor joists for an above level (i.e. t&g ceiling in the basement = bad).

le bossman: this is a ceiling/roof assembly. Also, I suspect 2x (even 1x) T&G provides at least a 15 min. barrier because when you look at section 2304 (for foam plastics) under "Roofing" (qualifying exceptions for the 1/2" gyp./15 min. requirement) code mentions .47" thick plywood at ceiling with specific edge conditions one of which is a T&G edge. So I have 2x T&G which, as I interpret, exceeds a .47" thick plywood as a barrier.

toasteroven: I must admit I was looking for the quick fix here at archinect. I don't have a UL book handy and tried to see if I could shake-out the UL language addressing this online (also, attempting to short-circuit buying one or going to the library -if any have a copy). Also trying to dodge gobs of phone calls and discussions to other manufacurer's, but I take your point to spec. something else. I already know of a rigid insulation with a cementitious face that meets rating requirements on its own, but it's a new product to me and I don't know all its ins-and-outs and cost. Also, California Building Code is based on IBC. I don't have it in front of me and I'm not aware of this matrix you mention. What section is it?

Many thanks for the feedback archicomrades.

1. the ul is online.
2. use the index in the IBC
3. are the 2x t-n-g tapered?
4. are you worried about heat or flame?

If you are not sure and/or confident that it won't hold up for 14 years don't be stupid!

dsc_arch:

1. I think tongue-and-groove is too racy for UL to address. I'm not having any luck (can't get past section 723 table of contents; can't even find anything in there on New Mexico green chile).

2. If I want to use an index, I wouldn't post on archinect ;) (I was just asking).

3. T&G is not tapered.

4. I'm worried about proving 15 min. barrier to plan checker and inspector as this is a limitation of use for rigid insulation. I have a project under construction and I'm trying to cut the cost of adding 1/2" gyp. over the T&G and looking for quick answers.

I'm out of my office today so I don't know the chapter #, but there are only a couple chapters on fire resistance - I'd start there.

I still think the manufacturer is your best bet for finding info on fire resistance... it's a better use of your time to call someone who will look this stuff up for you because they want you to spec their product.

Follow up:

I called the manufacturer I spec.'d to discuss their "limitation of use" and they were able to send an affidavit, that we could forward to our building official, essentially stating that the LofU is gleaned from code and that so long as the assembly stacks up to code requirements, it stacks up to their LofU.

Additionally, I emailed the American Wood Council about the rating of T&G and they were able to vouch for the rating of T&G - "more than comparable to the .47" wood structural panel" mentioned in section 2603.4.1.5.


I'm happy to share additional info./specifics at any time if anyone needs it.

And thanks again fellow archinectors for the feedback. I think toasteroven is on track with pressing the manufacturer.