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 access.

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.