June 27, 2024

New Multifamily Building Gains Maximum Benefits from Uponor PP-RCT and PEX-a Piping Systems 

by Brooke Roberts and Kim Bliss

Metropolitan areas across North America are continuing to see a demand for multifamily structures and high-density living spaces. And with each new project, the industry is discovering more and more innovative solutions to improve design, construction, and building performance that can benefit future builds. 

From low-rise complexes to soaring skyscrapers, the desire for sustainable, reliable, and efficient designs and systems continues to be a priority, while the challenge of meeting tight budgets and construction schedules remains at the forefront. 

One recent project in Northfield, Minn., was able to meet the needs of the engineer, contractor, and building owner by incorporating a complete polymer piping solution featuring PP-RCT and PEX-a for the domestic water system. 

The three-story, 105-unit complex used Uponor PP-RCT for the water mains into the building along with Uponor AquaPEX® for the domestic risers and in-unit piping. 

While the contractor had used Uponor PEX-a for risers and in-suite piping in many past projects, the decision to switch from copper to PP-RCT for the main piping was driven by budget, construction schedule, and worker safety. 

Newer to the commercial building industry, PP-RCT (which stands for polypropylene random copolymer with modified crystallinity and temperature resistance) is a lightweight, durable, sustainable piping solution available in sizes from ½" to 12", providing faster, safer, easier designing and installing of commercial domestic water as well as hydronic heating and cooling applications. 

The “R” in PP-RCT (standing for random) means the material is made up of both long and short molecular chains scattered randomly throughout the material. This random pattern staggers the joints in the molecular bond and greatly increases the ability to withstand elevated temperatures and pressures. It also makes the material more ductile and shatter-resistant for greater durability and performance. 

Uponor PP-RCT is produced with a special manufacturing process that enhances the crystalline structure, which produces a material with improved pressure ratings at elevated temperatures, providing a more than 50 percent improvement in long-term strength compared to PP-R. This long-term strength improvement allows designers to achieve higher pressure ratings with the same wall thickness, or potentially down gauge to a thinner-wall pipe with better hydraulic capacity and lower cost. 

PP-RCT piping systems also offer higher temperature ratings of 180°F (82°C) compared to PP-R pipe as well as lower levels of expansion and contraction in domestic hot-water applications due to the middle-fiber layer technology in the pipe. The system is available in various SDRs (standard dimension ratios) of 7.4, 9, 11, and 17.6 to meet any application need, and the pipe’s long-term consistent flow means there is no need to upsize the system to account for scale buildup or corrosion. 

PP-RCT is significantly lighter than metal piping systems, making it easier and safer to install while also alleviating added strain from the building structure. The joining system uses heat fusion technology, which eliminates open flame, hazards, and fire-watch requirements from the jobsite, making it safer for workers to install and also reducing construction hassles from the jobsite. Plus, the joining method cannot be dry-fit, adding greater confidence for a reliable install that will last. 

And because PP-RCT fusion connections create strong, reliable, monolithic joints, the system is also ideal for prefabrication opportunities. The stability of the connections makes it safe to assemble large spools in a controlled shop environment and then transport them to the jobsite for install. And again, because of the lighter weight of the product, the large spools are relatively easy to transport and get into position on the jobsite. 

Furthermore, PP-RCT — like PEX-a — resists corrosion, rust, and scale buildup, making it much more durable and sustainable compared to metallic piping. And the fact that polymer piping systems are not a traded commodity means contractors can bid projects with more certainty and confidence to help meet owners’ budgets and timelines. Additionally, there’s no scrap value, eliminating the concern of jobsite theft. 

Best of all, both PP-RCT and PEX-a piping systems from Uponor are confidently backed by a 25-year warranty, so engineers, contractors, maintenance personnel, and building owners can enjoy peace of mind knowing the piping system is designed and manufactured to stand the test of time. 

Because the owner of the plumbing company had worked with Uponor PEX-a for more than 30 years (back when it was originally known as Wirsbo), there was a high level of trust in the brand to venture into PP-RCT. However, since PP-RCT was a new material for the installers, Uponor and manufacturer’s rep FourMation Sales provided training and technical support both online and on site to ensure the contractors were comfortable and confident with the system. 

Another area of support FourMation Sales provided was the use of a heat fusion tool to make the PP-RCT connections. This enabled the crew to learn a new skill and also start working immediately with the piping material and joining method without having to wait for the purchase of new tooling equipment. 

The design included 4" PP-RCT along the ceiling of the garage to the mechanical room where it transitioned to 2½" PP-RCT to deliver hot and cold water to the 1½" PEX-a riser piping leading to each stack of units. The risers split off using Uponor ProPEX® engineered polymer (EP) multiport tees to deliver water to every fixture in each unit. 

With this design, because the PP-RCT is visible in the garage ceiling, the plumbing contractor wanted a clean, aesthetic look. To accomplish this, the team laid out plans and started making the necessary fusion-welded connections on the ground. 

“Since PP-RCT is up to 80% lighter in weight than metallic piping systems, the installers were able to prefabricate between 40 to 60 feet of PP-RCT on the ground and lift it easily into place, reducing the number of overhead connections needed,” said Patrick Schwappach, Uponor regional sales manager for North Dakota, South Dakota, Minnesota, and Wisconsin. “This not only speeds up the installation process for pipes of this size, but also reduces the physical labor on the installers.” 

When comparing Uponor PP-RCT to the alternative piping material — copper — the plumbing foreman on the job remarked on the significant upfront cost savings along with the faster install time. “A copper press connection would be much more expensive,” he said. “Using Uponor PP-RCT has gone very smoothly and has saved significant time.”  

The owner of the plumbing company echoed the sentiments stating, “It’s nice to have alternatives and to work with a company we trust.” 

Brock Johnson, Uponor PP-RCT portfolio manager, is proud to see the solution making a positive difference in projects for contractors, engineers, and building owners. “We’ve worked with industry professionals to get their feedback, hear their opinions, and help shape the future of our product line to make it even better for those who use it every day,” he said. “It’s great to see our customers benefitting in so many ways from these innovative solutions.”