FBC Fire Rating for Columns

[LearningAlways]

Guys.

We did a bad thing.

We are a precaster. We detailed and cast our R/C columns with only 1 1/2" cover to the main longitudinal. It was a miss, but we caught it before it was erected.

There any way around the minimum cover requirement of 2" (we need a three-hour rating)? They've cast five out of the 20 we have on the job, trying to save these five.

We've dug into the code, we are digging further into it tomorrow, but it seems hopeless.

 

[lexpatrie]

Intumesent coating.

I had this come up on a job down in Rochester, Minnesota (A rather notoriously rigorous building department, a la Scottsdale, AZ), and it was I believe a piece of exposed wood, I'm probably wrong, it makes far more physical sense for a steel column, but anyway, that would be an option, I think, so long as you can get the intumescent coating to adhere to the column, or some kind of steel cover over it. Retroactive fire rating is kind of tricky. Alternately, if the Architect of Record can find a way to legitimately drop the rating requirement to 2 hours with a different assembly, that's perhaps another possible path.

Was the 1.5" actually shown on the shop drawings so it got reviewed by the Arch/Engineer?

 

[ChorasDen]

Was the 1.5" actually shown on the shop drawings so it got reviewed by the Arch/Engineer?

I understand where you are going with this, but not sure I like the direction. Regardless of what was included on the OFA's, it is the responsibility of the delegated designer to align with the structural/architectural/service requirements of the structure as defined in the general notes and assemblies.

 

[lexpatrie]

Probably not, because what I'm getting at is if it's a full-on fabrication error that would be a different issue where you are asking for help on the issue, rather than, say, something "everybody" missed. It goes to the conversation, not some legal strategy.

 

[ChorasDen]

We detailed and cast our R/C columns with only 1 1/2"

Not sure I understand the comment you have regarding legal strategy, but oh well.

Regardless, I agree with Lex that it seems from first glance that intumescent paint may be a novel approach here, but can be tricky in that I expect you'll need to get the AHJ to sign off on this approach prior to implementing it, which may take some good story telling to get you where you need to be. I don't deal with RC columns, so perhaps it's an easier process in this particular industry (more available testing, data, reports, code exceptions, etc).

 

[lexpatrie]

I literally wrote it's not part of some legal strategy. What's the question?

If the architectural plan can tolerate it, intumescent coating (it's most decidedly NOT paint, the stuff is very thick, to me it's more like parging) might be a possible approach, or even roughen scrape clean of laitance and slosh concrete to the exterior of it to the necessary cover, adequately adhered with a bonding agent to keep in it place during a fire. Not sure who'd need to be the EOR on that one..... probably the overall guy.