RESIDENTIAL: Fire Safety
Why PEX-based Multipurpose Residential Fire Sprinkler Systems Outperform Standalone CPVC Designs
As states consider adopting the 2009 International Residential Code (IRC), which requires fire sprinklers to be installed in new homes built after Jan. 1, 2011, builders and plumbing contractors are ramping up their search for the most cost-effective and efficient fire-protection solution.
Many are turning to today’s most affordable and reliable life-saving technology: PEX-based multipurpose fire sprinkler systems. Already a mainstay in new-home construction, PEX (crosslinked polyethylene) is used in nearly three times as many new homes as rigid CPVC (chlorinated polyvinyl chloride).
Unlike standalone fire sprinkler systems created for commercial use that rely on rigid CPVC or metal pipe, multipurpose PEX-based systems combine the cold-water plumbing and the fire sprinklers into a single, efficient system. As a result, it eliminates one redundant piping system, reducing material, labor costs and jobsite-scheduling hassles, thereby saving 35 percent to 65 percent in installation time over standalone, rigid CPVC systems.1
In fact, installation costs for new multipurpose fire sprinkler systems average $0.57 less per square foot than traditional standalone systems.2 That translates into a savings of $1,368 for a 2,400-square-foot home.
"Multipurpose systems are specifically engineered for the demands of residential construction and the lifestyle of a family," explains Jayson Drake, senior product manager, Plumbing and Fire Safety, for Uponor North America. "Unfortunately, many installers cling to outdated commercial methodology and miss the efficiencies offered by multipurpose for the home."
Studies show that multipurpose PEX-based fire sprinkler systems have "the lowest cost of installation and the lowest amount of ongoing maintenance"3 for the homeowner. But lower costs are just one of the many factors behind the popularity of flexible PEX-based multipurpose systems.
In what might be the biggest advantage of all for builders, a multipurpose system needs only one subcontractor to do the work — usually the plumber already on the jobsite. This seasoned professional, typically a veteran of residential construction, is the one who combines the plumbing and the fire sprinklers into a single piping solution.
"Our existing plumber was able to install both systems at once, eliminating the need and the cost of a separate sprinkler contractor," says Emil Wanatka, president of Durango, Colorado-based Timberline Builders, which specializes in residential infill developments. "Any time you can eliminate a trade, it helps the bottom line. There are always conflicts over scheduling, training contractors to your floor plans and general worksite harmony. In our case, when it comes to subs, less is definitely more."
The reasons why PEX tubing outperforms CPVC pipe derive from the materials themselves:
In addition to the installation flexibility, watertight connections and cost savings that attract builders and contractors to multipurpose fire sprinkler systems, many jurisdictional authorities and homeowners prefer multipurpose designs for their reliability.
"For now, and until any further action by NFPA consensus standards committees, NFPA sprinkler standards prohibit the use of antifreeze in new residential fire sprinkler systems."
Another important distinction between multipurpose and traditional standalone fire sprinkler systems is that the latter require a backflow preventer, a check valve and/or a separate water meter.
Standalone sprinkler systems keep toxic, stagnant water out of the drinking water system with check valves or backflow preventers, adding cost and labor to these installations. To avoid contamination of a home’s potable water supply, some communities (Tacoma, Wash.) favor multipurpose designs, while others (Nolensville, Tenn.) require them and do not allow standalone.
Many states, fearing contaminated water flowing back into domestic lines, require a double check valve assembly (DC) or reduced-pressure (RP) backflow prevention valves. Besides the upfront costs for these extra components, they must also be inspected and maintained regularly. Likewise, the strength of any antifreeze mixture in a standalone system also requires an annual inspection, because antifreeze breaks down with age and must be replaced.
In contrast, multipurpose fire sprinkler systems contain only potable water and, therefore, require fewer add-on devices to maintain, inspect or fail. A multipurpose system is all but maintenance-free except for periodic visual checks.
First used in water distribution systems in the 1970s, PEX tubing systems have quickly grown in popularity because of their easy installation and durability, which allow contractors and builders to meet tight deadlines and even tighter budgets. In recent years, PEX has proven to be a highly effective alternative to CPVC pipe in residential sprinkler systems.
For the past 15 years, PEX-based multipurpose fire sprinkler systems have been listed in NFPA 13D, the sprinkler industry’s standard for the installation of residential sprinkler systems in one- and two-family homes. The International Residential Code (IRC) lists multipurpose residential fire safety systems under Section P2904, and acknowledges compliance with NFPA 13D.
PEX-based plumbing systems have a 40-year track record in millions of installations in homes and businesses worldwide. As one of the most thoroughly tested plumbing materials on the market today, PEX has proven to be the most efficient and cost-effective material for residential plumbing and fire sprinklers.
Multipurpose Sprinkler Systems: Summary of Benefits
Single-source Contractor. A multipurpose system needs only one subcontractor to do the work — usually the plumber already on the jobsite — eliminating the hassle and the cost of a separate sprinkler contractor.
Watertight Connections. PEX’s unique shape memory enables installers to make watertight, leak-resistant connections with no possibility of uncemented, dry-fitted joints. Moreover, the flexibility of PEX tubing reduces the number of connections, and potential leak points, by 50 percent.
Reliable Performance. A key benefit of these interconnected, multipurpose systems is reliability – homeowners cannot inadvertently shut off fire protection to their homes. In fact, homeowners know that water is available to their sprinklers each time they use a faucet or flush a toilet.
Cost-effective. Because multipurpose systems eliminate one redundant piping system, builders reduce material, labor costs and jobsite-scheduling hassles. These flexible systems can reduce installation time over standalone CPVC systems by up to 65 percent.
Low Maintenance. A multipurpose system is all but maintenance-free. A standalone CPVC system must have its backflow preventer or check valve professionally and regularly maintained, as well as the strength of any antifreeze. Studies show that multipurpose PEX-based fire sprinkler systems have ―the lowest cost of installation and the lowest amount of ongoing maintenance for the homeowner.3
Specially Designed for Residential. Unlike standalone fire sprinkler systems created for commercial use that rely on rigid CPVC or metal pipe, multipurpose fire safety systems are specifically engineered for the demands of residential construction and the lifestyle of a family.
1 U.S. Department of Commerce and the National Institute of Standards and Technology, NISTIR 7277 http://www.fire.gov/newsletter/fall2006/EconAnalResidSprink.pdf
2 September 2008 Fire Protection Research Foundation, http://www.nfpa.org/assets/files/PDF/Research/FireSprinklerCostAssessment.pdf, p. 11
3 "Comparison of Residential Fire Sprinkler System Service Options," Washington Water Utilities Council, October 2008. p16. A similar, 2007 study, "Benefit-Cost Analysis of Residential Fire Sprinkler Systems," by the National Institute of Standards and Technology, found that PEX-based fire multipurpose sprinkler systems offer the lowest life cycle. NISTIR 7451. http://fire.nist.gov/bfrlpubs/build07/PDF/b07025.pdf
4 PEX-a tubing is the preferred manufacturing process for producing crosslinked polyethylene (PEX) tubing because it yields the highest percentage of molecular bonding.
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