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Re: Fire Rating

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Jim,

To me, you really have two issues.  1) Will you system achieve the desired
fire rating? 2) Does it meet the requirements of a UL number for a 2 hour
system such as UL D920 (and there by also solving issue number one)?

I cannot give a "solid" answer on issue number one, but my guess would be
that yes the system can obtain a 2 hour rating.  That still leaves you
with the tough job of proving it (as infallible and all-powerful that I
might think myself to be, my opinion does not carry much weight <grin>).

That is where the UL number comes into play.  If your system matches a
system defined under a UL number then it is supposed to be able to achieve
the desired fire rating (duh, like you didn't know that already).  The
point, however, is that your system needs to closely match the system
described in the UL number.  Thus, if your grout matches "close enough" to
the concrete described in the UL D920 description then you should be fine.
This is usually a function of a minimum compressive strength and a
density, if I recall correctly.

If the grout does not really match up well, then using the UL D920 won't
really cut it.  You will then need to "prove" your system (assuming that
there is not another UL system that will work...which I am doubting...UL
would probably look at the grout as not being permanent since in theory
you could have a future occupant that removes the grout and tile and just
replaces it with carpet with the 3.5" of concrete...admittedly not too
likely since they would like need to do something to get rid of the change
in elevation of the floor surface from the 5" concrete to the 3.5"
concrete).  This could be done by testing, but also could potentially be
done by proving that your 1" of grout is roughly equivalent to the .5" of
concrete.

HTH,

Scott
Ypsilanti, MI


On Wed, 27 Nov 2002, Jim Kestner wrote:

> We would like to construct a concrete floor using  UL D920 with 4 1/2" min.
> of normal weight concrete above an approved composite metal deck that has 2
> hour fire rating with no fireproofing. If the floor is poured with 5" over
> the deck, then where we have grout set tile (1 1/2" depression)  we would
> have only 3 1/2" of concrete over the metal deck plus 1" of grout as a
> setting bed for quarry tile. Would this meet the 2 hour fire rating? We
> would not count the quarry tile as contributing to the fire rating.
>
> Jim K.
>
>
>
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