How a Combination of Planning, Prefabrication and PEX Can Produce a Successful Project

On large commercial projects, careful planning along with prefabricated piping assemblies and PEX can cut time off the production schedule and potentially provide bigger profit margins

How a Combination of Planning, Prefabrication and PEX Can Produce a Successful Project

Instead of building the entire system on site, producing piping assemblies in a predictable, controlled, factory environment prior to installation offers many advantages from a time and labor standpoint. 

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The preconstruction phase has a significant impact on a project. This is where careful planning and coordination can offer the greatest benefits on project costs, schedule and profitability.

As a project moves forward, the ability to make decisions that will have a significant impact on the cost outcome of the project diminishes. So incorporating a solid preconstruction phase with the inclusion of prefabrication can have a heavy influence on costs and greater control over profit margins.

Surprisingly, the level of efficiency on a construction site is pretty much the same today as it was in the 1950s. In fact, a study by the Mechanical Contractors Association showed only 32% of labor hours on a commercial job site are spent on direct installation of equipment and piping systems. This means that for an 8-hour workday, only about 2 1/2 hours are spent on actual productive, profitable activities. The remainder of the workday could include things like material handling, equipment setup, job site cleanup, meetings, breaks, rework and testing setup.

While some of these activities do help contribute to the installation and are important to the project, the challenge actually lies in executing these activities more efficiently during the time spent on the job site. Planning, coordination and prefabrication helps increase the percentage of time that crews spend on direct installation while reducing the time spent on non-impactful activities.

Starting with the right plan

Let’s take a look at planning and coordination to see how this affects a project’s timeline and efficiencies.

When starting a project, creating a design with 3D coordination and clash detection is superior to a traditional 2D design. Adding clash detection to the 3D model coordinates systems across multiple disciplines, including plumbing, mechanical, electrical and structural.

Clash detection helps to ensure different trades aren’t running into each other in the same space. For example, a plumber may be planning to run pipe through the same space the HVAC contractor is planning to run ductwork. Or there could be plans to place equipment in the same location where a wall or other structural component may be located.

Coordinating the project with 3D modeling and clash detection puts all the models together for plumbing, mechanical, electrical and structural, and lays out all the systems into one 3D model based on the owner’s requirements. Clash detection eliminates conflict on the job site, wasted time coming up with a resolution, and expensive change orders. By bringing all these systems together into one 3D model based on the owner’s requirements, you are able to discover and correct issues before the project even breaks ground.

Positives of prefabrication

Once you have your design in place, deciding on prefabrication can shave days or even weeks off a project’s timeline.

Producing piping assemblies in a predictable, controlled, factory environment offers many advantages for contractors from a time and labor standpoint. Having employees doing repeatable work in a factory adds greater efficiencies and can even produce higher-quality installations when supervisors can easily do quality checks on row after row of prefab racks rather than walk for miles on a job site.

After making dozens, hundreds or potentially thousands of prefabricated jigs or racks in a factory environment, a simple haul to the job site is all that is necessary. Once they arrive on the job site, you just take them out and set them in place. No on-site material handling or assembly required.

There are several different prefabrication applications. For example, racking in prefabrication involves taking a number of spools and attaching them to hangers and supports, then assembling them off site and shipping them to the job site when ready. They are then set in place as a single unit.

Multitrade racking includes the material coordination and installation from several trades. For example, you could have plumbing, mechanical and electrical work all installed on one rack. Once the rack is complete, the whole assembly is delivered out to the job where the various trades responsible for the rack make their tie-in connections.

Think about the efficiencies of this type of system. If all these trades were trying to build their systems from scratch in one area, there is no way all that work could take place at the same time. This is where projects can really save time, money and days on the construction schedule.

Why PEX is great for prefabrication

While PEX has been around for nearly 40 years in the residential market, it is still relatively new in the commercial world. But professionals in the commercial construction industry are turning to PEX more often for plumbing and mechanical piping for the same reasons it became popular in residential decades ago.

PEX does not pit, scale or corrode. It is flexible for fewer required fittings, and it can expand and contract for greater resiliency in freeze-thaw cycles. For a piping systems contractor, PEX has several benefits over copper, CPVC, steel, black iron pipe and other metallic systems. PEX is lightweight, allows for faster installations, provides easy connections, and offers more stable material costs along with less expensive system costs (when you include labor comparisons).

In a project using prefabrication, the lighter weight of PEX is a big factor. For example, a 20-foot length of 3-inch PEX pipe weighs a mere 26 pounds, while copper is more than double at 67 pounds and steel is 152 pounds. All that weight makes a big difference when moving the product and getting it ready for prefabrication.

Another big difference is the connection system. For PEX, you can use various systems, such as crimp, clamp, compression, expansion or push-to-connect. Most professionals choose ASTM F1960 expansion because it can’t be dry fit and it’s the only PEX connection that actually gets stronger over time.

One important point to note when installing PEX — it is imperative you stick with the same manufacturer for the pipe and fittings. This is important because some manufacturers design their pipes and fittingsto work together for the strongest performance. Also, it ensures full system warranty coverage along with technical support, if necessary.

If you are interested in learning more about PEX pipe and fitting systems, visit the Plastics Pipe Institute website at or the Plastic Pipe and Fittings Association website at

About the Author

Kim Bliss is the content development manager at Uponor. She can be reached at


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