huangyhg

cast iron column - fire rating
has anyone ever tried to come up with a ul listing to make an existing cast iron column 2 hr rated? if so, please give references.
thanks
are you looking to cover it or spray something on it or fill it with something to keep the original shape?
why not just enclose it in a 2 hour rated enclosure? something like steel studs with two layers of 5/8" drywall should be enough, but you must verify that with the ul details.
an interesting article in december-january edition of structure magazine on fire protection:
the cast iron column is in what will become a parking area. it is round with a tappered base plate. it would be difficult, but not impossible to cover in studs and gyp but i am trying not have to do anything if it isn't necessary.
don't know about the fire rating, but would that column have to withstand impact load? cast iron can be quite brittle...
the column is about 1-1/2 inches thick wall, and about 24 inches in diameter. it would take one hell of a load to do anyting to it. it is supporting a 12 story building.
that's a horse of a different color! i was thinking of a 6" or 8" column at the interior of an office or commercial building.
you will definitly have to fireproof it and if you think about what you see in other parking garages i would bet you are looking at spray-on fireproofing, concrete or masonry enclosure. what does your local building code offical say? have you looked for approved ul listed assemblies in the ul book? you could also call underwriters labs and talk to someone in their techncial services department, although you might have to subscribe to their service to get a written answer.
ul was called last week, but of zero help. all of there assemblies are for steel, not cast iron. i don't know very much metalurgy, but i do seem to recall that cast iron will act very differently to heat/flames. i was trying to avoid doing anything to it but conservatively we would just to cover ourselves. right now we are persuing the building code official to hear what their verdict is but they would likely follow our recomendation if we had one.
thanks for the help.
just a thought, but take a look at filling the 20" diameter cast iron columns with concrete. would a plain, unreinforced column 20" in diameter carry the column load if the cast iron column melted away? what percentage of the total column load would the added weight of the concrete be on the supporting footing? i'm again assuming (i hate that word) that this is the lowest level.
you could make a reasonable argument that the column is protected in the unlikely event of a fire and yet the cost wouldn't be that great, the cast iron column would be the form for the concrete.
just a thought.
good thought jheidt, but the walls of the cast iron are between 1 1/2 inches and 2 1/4 inches (this i get from a 1930's design guide for round cast iron columns. i would say it is very difficult to open a sufficient hole in the columns (our contractors guess is that would be about a 4-6 hour hole for an iron worker to create.
unfortunately i'm really outside the box on this one. the building code official has been little help - he said its not combustable and therefore doesn't need to be protected!
this is a car parking and cars burn as you can see in any hollywood movie. sometimes, in real life as well and the authorities are not doing justice to their jobs if they say no protection is required.
one option will be to embed the entire column into concrete. this can be done by wrapping wire mesh around the existing column and then plastering with air entrapping concrete. the mesh should be able to act as reinforcement and hold the concrete layer in place. though i do not know how practical it will be in your case.
bfn

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