Fire stop

Here's what you need to know to assure building fire safety in the construction process.

If you think today’s buildings are extremely safe from fire dangers, think again.

While architects and engineers are designing buildings to be less vulnerable to spreading flames, something much more insidious is taking lives in fires. Smoke and toxic fumes that follow the penetrations in walls for piping, wire runs and HVAC ducts are today’s top killers in fires.

“Insurance companies are paying more attention to how well buildings are protected from fire and smoke moving from one area to another through wall penetrations,” says Robert Gram of Nelson Firestop, Inc. “We are seeing greater enforcement of codes modeled after the National Building Code published by the Building Officials and Code Administrators, Inc. (BOCA); Uniform Building Code published by the International Conference of Building Officials (ICBO); and the Standard Building Code published by the Southern Building Code Congress International.”

Firestop is more than sealing up the gap between the penetrating material and the wall. It’s a system that is designed to counteract the effects of flames, heat and smoke, says Jim Park, national sales manager at Rectorseal.

Specifications drive the process
In general, the codes mandate that any penetration in a firewall must be effectively treated to prevent smoke or flames from leaving the burning area. It must also prevent air movement into the fire area through the penetration, Gram says. “Engineering or architect specifications usually drive the selection of firestop products and contractors are required to install them correctly,” he says.

An effective firestop system relies on three essential areas that must be executed properly, says Gram. “First, the architect and engineer must specify the correct system to seal the penetration effectively,” he says. “The delivery system that gets the firestop product to the jobsite and installed correctly is the second component of the system. Application training is key,” he says.

The third key to establishing an effective firestop system is enforcement. “That includes making sure local building codes properly address firestopping issues and that inspectors are trained to recognize whether the firestop installation properly protects the building.

“The system is everything. It is based on the configuration of the wall. It considers the size and type of penetration and the firestop material required for that configuration,” he says.

Park says contractors are often instructed by building inspectors to modify firestop systems to meet what they believe is the correct firestop method. Or, the contractor takes it upon himself or herself to adapt the system.

While building officials have local jurisdiction, their authority should not extend to specify and modify the firestop system. “Inspectors do not have the authority or the liability exposure to modify firestop systems. They are designed for a specific application. They are developed based on tests conducted with materials under certain conditions. If the condition outlined in the firestop system does not match the condition of the job, it’s not the right firestop system,” Park says.

Firestop types for different penetrations
There are two distinct types of materials used in today’s firestopping systems, although these materials alone are not fireproof. Gram says the type of penetration needing protection drives the system you use.

Intumescent firestopping materials, when heated, expand to fill voids. They are the necessary choice in penetrations that have combustible materials such as plastic pipes, insulated wires or cables.

“As the insulation or plastic burns away, these materials heat up and expand to fill the void left by the burned material,” he says. The plugging action of these compounds prevents air from being pulled through the void, which could feed the fire.

Intumescent materials are generally water-based materials that come in caulk, putty or sheet formulations for different applications. “These materials are easy to work with and clean up with water,” he adds.

Endothermic firestopping materials are used to protect metal penetrations such as pipes or conduit. “These materials absorb heat and then char on the surface. The charring sets up a fire barrier that keeps the penetration sound,” Gram says.

Endothermic materials are slightly less expensive than intumescent materials. “It’s important to note that you can not use endothermic firestop on burnable materials such as wiring or cables,” Gram says.

Other spray-on products are available to seal wall and ceiling joints. Many types of endothermic firestopping materials aresolvent-based and release volatile organic compounds (VOCs) as they dry. “You may need respiratory protection as you apply these materials. They also may be flammable until they dry,” says Gram.

Above all, the firestopping material must maintain some flexibility once installed to allow the wall and the penetration to expand and contract. “In areas with seismic activity, flexibility is very important. The firestop must be able to move with the movement of two dissimilar materials, ” he adds.

Product selection tips
Although it is tempting to cut corners by using a less expensive product, Gram advises against it. “On one job, a low-cost firestop product was substituted for what was specified. The contractor applied the product to sprinkler system penetrations. When it dried, it didn’t flex, so when they started charging the sprinkler system, the pipes hammered and the firestop cracked on many joints. The contractor had to go back and remove the inferior firestop material from over 12,000 penetrations and replace it,” he says.

Another contractor attempted to concoct his own firestopping material out of drywall mud, recalls Gram. A savvy inspector identified the product was not what was specified and the contractor had to chip away the mud and replace it with the specified product.

“It’s important to use products that are UL-registered and installed according to the firestop manufacturer’s directions. These systems have been tested extensively. When you find that the system doesn’t exactly match the application for which the product is registered, that’s when you call your distributor or firestop manufacturer. The manufacturer can make a determination which system is adequate for the application,” says Park.

The future of firestop
Park, who has been involved with firestop installation, training and development for over 25 years, says contractors overlook the importance that proper firestop installation plays in building safety.

“It’s often the lowest-paid workers who install firestop and they often aren’t trained correctly in the application. This results in the workers either using too much firestop material, or installing it incorrectly so that it can’t perform as a system if there ever is a fire,” he says.

Just as sprinkler systems are required to be installed by licensed contractors then inspected by knowledgeable, impartial third parties and get a seal of approval from the fire marshal, Park predicts that firestop will be treated in the same manner in coming years.

“Proper firestop specification and installation has been in building codes since 1985, but it’s now just starting to get enforced,” says Park. A recently formed association, the Firestop Contractors Installation Association (FCIA) is working on code language that it hopes to incorporate into future building codes. “It’s at least three years off, but the language they are recommending will require firestop to be installed by licensed contractors with inspection provisions and fire marshal sign-off, much like what’s in place for sprinklers,” he says.

Published in the March/April 2001 issue of Contractor Tools and Supplies magazine.

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