you are confusing the difference between fire rating with
flamespread and combustibility. Did the stairwell fire breach the
wall into adjacent areas? The fire rating was still acceptable due
to the base underlying material. It failed OTHER requirements.
Roland
On Mar 10, 2008, at 8:12 AM, å... .... wrote:
I understand your reference, but when you say "put any
covering over a base material..." I don´t follow the logic.
For instance, we would not allow bare polystyrene to be
put on the walls (even if it were an refrigeration unit). Such
an application, I doubt would increase the FRR of the assembly.
We would apply another layer over the polystyrene that was
noncombustible, or worse yet, we would attempt to solve the
problem with fire resistance chemicals (the worse being
polybrominated diphenol ethers).
I remember a fire in a New York city burrough staircase. Oil
based paint had accumulated on the walls from years of painting.
It was precisely this paint, albeit only mils thick, that ended up
seriously injuring or killing someone with an open door at the top
of the stairs. Although my application is a sprinklered corridor
without
the
vertical flame spread a stair tower leverages, I still want to be
careful what goes on the walls and ceilings in the exit access,
as I know you do as well.
Incidentally, neither American Gypsum or National Gypsum have
responded to my inquiries to their desk and mobile telephones. I
am still pursuing an formal interpretation.
This application in question--Vinyl---contain chlorides but it is
still double the heat content of paper. And the paper still lays
behind the vinyl. Am I really worried? No. Am I curious as to
what the
formal interpretation is? Yes.
scot deal
excelsior fire
On 3/10/08, Larrimer, Peter A <[EMAIL PROTECTED]> wrote:
Scott,
This brings back a lesson at the University of Maryland.
Harmathy's Rules
of fire resistance would indicate that you can put any covering
over a base
material that has a rating and the rating will only go up. The
interior
finish rating will be different and possibly a concern, but the fire
resistance rating of your Type X gypsum assembly will not
decrease. Check
out the following for a discussion on Harmathy's rules and
specifically Rule
2. I don't think that it is restricted to wood, but it may be.
http://www.fpl.fs.fed.us/documnts/pdf1988/white88a.pdf
Pete
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