Penetration Seal Products
The number of materials available for penetration sealing from
fire protection manufacturers has grown substantially over the
past few years. This product category now includes caulks and
putties, sealants, tapes, joint strips, composite metal sheets,
mechanical devices for plastic pipes, cast-in-place devices, and
a variety of insulating bags, pillows and blocks.
Caulks, putties, wrap strips and tapes for penetration fire-stopping
commonly exhibit both intumescent and endothermic properties.
Caulks are applied around penetrating items with a caulking gun
to form a seal against fire, smoke, fumes and water, while putties
are pressed into openings manually. Tapes and strips are wrapped
around objects and gaps. These materials are generally used to
seal penetration gaps created by cables, pipes, wires, ductwork
and similar fire barrier penetrations.
Composite metal sheets are useful for openings that are too large
to be sealed with caulk or putty alone, such as large gaps in
concrete or gypsum walls where conduit, pipes or ducts pass from
one area to another. Composite sheet consists of galvanized metal
panels sandwiched around an intumescent rubber matrix. Composite
sheets are cut to fit closely around penetrating elements, fastened
tightly to the fire barrier, and sealed around the edges with
rated putty or caulk.
Special plastic pipe devices and related components are used
to seal openings completely should a plastic pipe burn or melt.
Such materials consist of metal supporting collars to hold an
intumescent material in place around the pipe, as well wrap strips
and putty to seal the annular space between the pipe and wall
or floor surface.
Various fire-stop sprays, made of latex, or other formulations,
are used for penetration situations such as curtain wall safing
joints, expansion joints or head of wall joints where caulk is
slow or awkward to install. These materials, are typically intumescent
and ablative formulations, can be sprayed or brushed into place
to help control heat conduction, and restrict passage of smoke,
gas and water. They are typically applied over a substrate of
compressed mineral wool insulation that has been used to fill
the gap. Firestop sprays are typically elastomeric, and dry to
form a flexible seal that can tolerate some vibration and movement.
Firestop mortar is a plaster-like material that can be troweled,
poured or pumped to fill large openings around pipes, cable trays
and ductwork. It bonds to most surfaces and sets up to form a
water-resistant barrier that does not shrink when drying or under
the heat of a fire.
Firestop foam is applied in a manner similar to caulk, and is
useful for fire-stopping small to medium sizes irregular or difficult
to reach openings. This material expands to fill spaces that are
un-accessible to conventional putty or caulk.
Firestop pillows, bags and blocks are used to fill large openings
such as around pipes, ducts, cable bundles and cable trays. These
items combine intumescence with insulating properties, and are
sometimes used in conjunction with other products including composite
sheets and putties or other sealants. They are removable and replaceable,
which is important for structural areas that may require reentry
Cast-in-place devices are plastic or metallic sleeves that are
cast into a concrete floor at the time of original construction.
They contain an inlay of intumescent material needed to seal off
the penetrating items in the event of a fire. The penetrating
item is simply pushed through the device as building utilities
are being installed. Such devices allow future retrofits without
having to break through or destroy the sealants.
Mineral wool is used to fill open spaces such as penetrations
with large annular spaces or head-of-wall joints, and at the intersection
of edge of floor slabs with exterior walls. This material can
be compressed and fit into place, and its permanent resilience
can withstand structural movement to remain permanently in place.
Mineral wool is used to increase the thermal rating of the through-penetration
fire-stop systems and provide backing to the sealant material.
A Continuing Challenge
The effectiveness of penetration fire-stopping depends greatly
on proper training and consistent installation methods that meet
governing standards and comply with local codes. This work can
be accomplished by specialty contractors, or by general contractors
and sub-contractors who are trained and equipped to meet these
standards. In either case the work should be subject to rigid
inspection in accordance with governing codes, and conform to
ASTM standards (ASTM E-2174.). While penetration seals are generally
installed at the time of construction or during rehabilitation,
it is critical that there be ongoing attention to penetration
seal details over the life of a building, since ongoing maintenance
and service changes inevitably create new holes in fire-rated
barriers, and leave previously filled and sealed openings empty.
Without proper attention to these penetrations, the integrity
of the fire barriers can become critically compromised.
While there are dozens of qualified fire-stop materials and documented
applications on the market, each construction project presents
special situations that may not be precisely defined in established
procedures. The major fire protection suppliers listed below are
equipped with technical service departments that provide engineering
judgments for such installations based on laboratory tests and
product experience. These manufacturers generally offer application
engineering assistance and on-site training to help contractors
comply fully with penetration fire-stop code requirements.