Intumescent tape - Marino\WARE

Intumescent Tape
Is on the rise (No Pun Intended)
Intumescent tape: One product to fill many needs.
By Don Pilz
Intumescent tape has changed the
fire-stopping industry for the better
over the last few years and is
now doing the same for sound walls.
Once primarily used for fire-rated
doors, safes and gun cabinets, intumescent
tape is now used for building
joints with phenomenal results
for fire and sound protection.
As structural engineers continue
to design buildings requiring more
and more dynamic movement, the
benefits of intumescent tape could
not have come at a better time. The
reason intumescent tape works so
well is because it’s relatively thin and
can be concealed within the framing
assembly without hindering movement.
However, intumescent tapes
can’t merely be “field-installed” into
the framing assembly. The position
and location of the intumescent
tape is critical to the effectiveness
of the joint assembly. That is why
steel/intumescent composite tracks
are tested and certified with Underwriters
Laboratories. Each building
joint assembly is tested through UL
according to UL-2079 Tests for Fire
Resistance of Building Joint Systems.
Some intumescent tapes expand up
to 35 times their original size. With
this type of performance it’s no wonder
steel framing manufactures have
sought out different ways to utilize
the capabilities of intumescent tapes.
CEMCO FAS Track 1000 is just one
example of the efficient use of intumescent
tape within a steel deflection
track. Intumescent tape is attached to
the upper web along the outer edges
similar to what contractors have done
for years with foam tape to increase
STC or IIC sound ratings. The tape
works as a gasket, sealing off irregularities
in the structure. It also works
as an isolator lending a sound deadening
element to the deflection track.
This type of fire-rated deflection
track can increase STC ratings of the
wall assembly without the traditional
usage of fill materials such as acoustic
sealant that can prohibit the amount
of dynamic movement.
Currently, field applied sealants at
the head-of-wall, whether they are
acoustic or fire sealant can drastically
reduce the movement capabilities of
the joint. In recent year’s sealant manufacturers
have responded to this issue
by making the head-of-wall joints
wider with more flexible material so
they can provide greater movement.
The typical sealant filled head-of-wall
joints can range in size from 3/4 to
1 inch wide, and although the larger
joint will provide more movement they
generally will not get more than 1/4
inch compression or extension before
they tear away from the drywall, leaving
an unprotected gap within the
building joint. A tear or crack in a
sealant filled joint system means it has
failed as a fire stop before it has even
been called upon to perform.
THE DILEMMA
Most concrete multi-family structures,
such as hotels or condos,
require 3/4 inch overall movement.
At the same time the UBC requires
Sound Transmission Class ratings
and Impact Insulation Class ratings
for dwelling units, which include
hotels, motels, apartments, condominiums,
dormitories, and monasteries
to be at a minimum 50 STC
or IIC rating. Sound ratings can be
greatly reduced through sound flank-
Left Image: This drawing shows an open unencumbered joint with
intumscent tape positioned on the web of the track (HW-D-0624
drawing courtesy of CEMCO)
Right Image: HW-D-0576 Drawing courtesy of CEMCO
18 | Walls & Ceilings | January 2013

BlazeSeal intumescent tape. (Courtesy of Rectorseal
Test Lab)
After 3/4 inch movement test, according to
UL-2079, the acoustic sealant separates from
drywall (Photo courtesy of Rectorseal Test Lab)
After burn test, intumescent tape expands to
completely fill in head-of-wall gap (Photo courtesy
of Rectorseal Test Lab)
ing paths. To reduce flanking paths,
drywall should be sealed tight to the
framing member around the perimeter.
However, in traditional metal
stud framed walls, framing screws
that attach the stud to the track cause
the drywall to hump up around the
framing screw that provides a flanking
path and increases sound transmission.
Sound ratings can also be
reduced in metal stud framing at the
hard connection between the metal
track and the floor or ceiling. For
this reason, resilient partition isolation
pads, acoustic sealant or foam
tapes are sometimes utilized between
the track and the ceiling or floor to
reduce the potential sound loss due
to flanking paths. But none of these
sound aids provide fire protection if
movement is required.
What’s the contractor to do? On one
hand, you have to provide an average
of 3/4 inch overall movement for the
building structure. On the other hand,
you are required to provide applicable
sound protection for dwelling units.
Traditionally sound protection and fire
protection do not work hand in hand
when movement is involved.
Making matters worse, contractors
are bidding projects in a very competitive
environment these days and in the
past the traditional means and methods
of a sealant filled head-of-wall
joints were not watched very closely
by the inspectors. So head-of-wall fire
rated joints could be done relatively
inexpensively by installing smaller
width joints of 1/4 to 1/2 inch which
will save material and labor costs rather
than what is actually called out on
the UL report at 3/4 to 1 inch. When
you take into consideration the overall
movement is based on the width of the
joint and the percentage of the compression
or extension listed on the UL
report (typically listed at 18 to 25 percent)
it is clear that making the joint
smaller will only limit the amount of
movement causing the joint to underperform.
Most buildings are designed
with a certain movement criteria. Certain
walls within all structures are
also designed to be fire-rated to enable
safe egress hence the requirement for
fire-rated walls with dynamic movement.
A fire-rated joint that underperforms
may not sound like a big deal
during construction but if by underperforming
the joint splits open and
allows smoke to pass through the wall
it can put lives at risk.
SOLUTION
Find out the movement requirement
of the building structure and find a
joint system that will provide it. If the
UL report requires a 1-inch joint filled
with a particular type of fire sealant
then install it accordingly. If acoustic
or fire sealant will not provide enough
movement find something that will.
There are deflection tracks with factory
applied intumescent tapes, such
as CEMCO FAS Track 1000, that will
provide fire, smoke, and sound protection.
This product is certified through
UL according to UL-2079 and can
meet greater deflection requirements
with no fatigue splitting or cracking.
But what if the project is already
underway and the top track is already
installed when you, the contractor
find out the movement requirement is
greater than what is achievable with
fire sealant? It’s a little too late to
switch out the installed deflection
track for one with a factory applied
intumescent tape. There is a solution.
CEMCO DDA (Deflection Drift
Angle) is a light gauge composite steel
angle with intumescent tape along the
inside leg which can be tapped into
place over the leg of the installed top
track. There are no mechanical fasteners
required for installation. The
3/4-inch horizontal leg of the product
is friction fit between the web of the
track and the overhead structure. This
allows the wall assembly to move vertically
and laterally without compromising
the fire stop material. This type of
fire-stopping product has other advantages;
provides a universal fit for any
wall width, gauge, height, whether the
wall is standard, shaft wall, radius, or
raked. It can go over either slotted or
deep leg deflection track and finally it
can provide up to 1¾-inch unencumbered
joint protection.
CONCLUSION
Do your research when selecting
head-of-wall fire protection. Make
sure the manufactures joint system
has been tested according to UL-2079
“Tests for Fire Resistance of Building
Joint Systems” and can provide
the movement the building structure
requires. If you decide to go with a
steel/intumescent deflection track,
make sure it has been sound tested
and can meet the required STC rating.
Finally, field installations can be very
difficult make sure the joint system
is being constructed as intended and
described in the UL report. Underperforming
joints are unacceptable, especially
in multi-family dwellings. W&C
After 23 years in the construction
industry as a foreman
and building envelope consultant,
Don Pilz is now the R&D
Manager for CEMCO, assisting consultants
and contractors with detailing needs. He
can be reached at dpilz@cemcosteel.com.
January 2013 | www.wconline.com |
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