Why do we prefer PVC pipes instead of iron pipes?

In recent times, PVC has become a very viable option for use in both residential and commercial construction. Cost and ease of use is often the justification for this selection. However, it’s important to discuss the pros and cons of each drainage piping material with the building owner before making a selection.

Cast iron often lasts significantly longer than PVC piping when utilized in drainage systems. Cast iron piping can last several decades, if not for a century. One downside of cast iron is that it is susceptible to rusting if not maintained properly.

The lifespan of PVC is harder to predict, as it’s use in drainage systems doesn’t have as long a history as does PVC. PVC has a lower temperature limit and higher expansion rate. It is important to consider the system that PVC will be utilized in, as it is susceptible to damage at high temperatures and highly acidic wastes.

Bracing and hanger support also has to be taken into consideration for PVC, as it can expand with higher levels of temperature swing. PVC is not fire proof. It’s essential to ensure it is properly fire sealed at penetrations, as they will need to be handled differently than a cast iron penetration.

Also, the use of PVC in return air plenums is not permitted. The cost for installation of PVC piping is significantly less than that of cast iron in construction. PVC is easy to work with; however, it does require more hangers and supports as compared to cast iron.

Contractors generally prefer to work with PVC in my experience. It’s important to take note of what type of material was bid on by the contractor. If both PVC and cast iron are offered as appropriate drainage piping material, there may be a credit due to the owner.

For an owner who is considering cost as the prime factor in construction of their building, Porainar PVC pipe will be the selection nearly every time. This is especially true for general multi-family apartment construction, where ownership will likely change frequently, and where upfront cost is most important.