With
some exceptions, making a penetration in a gypsum board ceiling when it is not
used to maintain a fire-resistance rating poses few problems. Unless the system
is being used as a sound or smoke barrier, or as part of a seismic- or
wind-resisting system, you pretty much can cut the hole, run the penetrating
element, seal around the hole with some joint treatment, and walk away.
When the installation is evaluated, appearance of the finished interface
between the penetrating item and the ceiling membrane, not the function of the
ceiling system, is usually the determining factor.
Once you add the element of a fire-rating to the situation, the scenario changes
significantly, because once you penetrate the membrane of a fire-rated ceiling
(or the ceiling system if it does not have a membrane, for that matter), you
bring into play a host of code requirements.
Penetrations in gypsum board fire-rated ceilings (and let’s stay with ceilings
in this column to keep it simple; many of the same requirements apply to walls
also) typically are of two types: items that penetrate the entire system, such
as a pipe or duct; or items that penetrate only the membrane of the system:
again a pipe or duct, but also possibly an access door or length of electrical
conduit.
Requirements for the proper installation of the penetrating items are contained
in Chapter 7 of the International Building Code; however, even with the code
language one common question often arises: “How do I penetrate a rated ceiling
if the system being penetrated did not contain the penetrating item when it was
fire-tested?”
In other words, “You’ve said loud and long not to modify a rated system from
the way it was tested. I look in your Fire Resistance Design Manual (FRDM) and
I don’t see any systems with penetrations. What do I do
now?”
The Simple Answer
The fire test on the ceiling establishes the rating for the system. If that
system is to be penetrated or compromised, the modification has to be
accomplished in accordance with the procedure outlined in the code. Construct
and install the gypsum system in accordance with the design contained in the
FRDM. In addition, install the penetrating items based on the listing or test
that is being referenced, noting that the source for the fire test information
will be a document other than the FRDM.
Code language and penetration element testing have evolved to the point where
the individual penetrating item is required to pass a specific fire test before
it can be installed in a rated system. For example, an access door that is
installed in a rated ceiling must, according to Section 711 of the IBC, be
“tested in accordance with ASTM E 119 [for] horizontal assemblies and labeled
by an approved agency for such purpose.”
Section 711 on Horizontal Assemblies doesn’t indicate the specific rating that
the ceiling system has to maintain. That information is found in other sections
of the code. But it does establish that the rating of the system shall “not be
less than that required by the building type of construction.” It therefore
follows that if the horizontal system has to provide a specific hourly rating,
then the access door has to provide, at a minimum, the same rating also;
however, it does not require that the exact, specific ceiling system and the
precisely designated access door have to be tested together.
In other words, if the ceiling system provides a one-hour rating, then the
access door has to have passed an E119 (or equivalent) test where it also
achieved at least a one-hour rating. The code does not require the specific
access door in question to have been tested with the exact ceiling system being
installed; however, it does require the access door to have been tested for use
for the purpose intended.
Listings and labels describe the systems in which an access door can be
installed and the basic requirements of the system. With a gypsum board
ceiling, the listing might describe the type, thickness, and number of layers
of board required; the spacing of the framing members; and the method of
fastening the door to the system.
Pipes and ducts that penetrate a ceiling and fire-resistant joint systems
between ceilings and other rated systems have similar requirements. In the
instance of a pipe that penetrates a ceiling, the specific listing might be
limited in use to a specific series or type of ceiling system-it might be limited
to use with only wood joist systems covered with structural wood panel
subflooring, for example-but it is a pretty rare occurrence when a system would
be tested with and limited to use with only one specific floor-ceiling system.
Again, the listing for the penetrating item will describe the construction that
is appropriate for use with the penetrating item and it may do it in broad
terms. As an example, systems described in the Underwriters Laboratories Fire
Resistance Directory often refer to a series of similar designs with which the
penetrating element may be used. This makes complete sense, for you would not
install a 4-inch diameter pipe in both a wood joist and a steel joist system
and expect to get the same result. You would however, expect to get the same
result from the same diameter pipe when it was repeatedly installed in a series
of comparable wood joist systems.
The IBC requires items that penetrate ceiling systems to be tested in
accordance with ASTM E 814 or UL 1479 as modified by the code. Similar language
is contained in the code for duct penetrations and fire-resistant joint
systems.
Given the countless penetrating items that exist and the potential unlimited
combination of items and systems that might occur, it stands to reason that
requiring each penetrating item to be fire tested with each specific system
would be a boon to no one other than a testing lab. It would lead to a
situation where the number of building construction methods would be severely
limited or the cost to construct a building would increase significantly due to
testing requirements. Neither outcome would serve the public interest very
well. W&C
All Things Gypsum: Penetrating Fire-Rated Gypsum Board Ceiling Systems
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