PEX tubing is becoming increasingly popular because it’s less expensive than copper and uses considerably less energy to produce. But this plastic pipe isn’t without its problems, including a propensity for rodents to gnaw on it, even in insulated installations. Several experts—including Tomas Lenman of Mr. PEX, Tom Coe of NIBCO, and Dale Stroud of Uponor—share their advice for installing PEX plumbing safely and avoiding rodent damage.
PEX is made from polyethylene molecules that are chemically linked together, changing it from a thermoplastic to a thermoset material. The linkage is accomplished through a process called cross-linking, first developed by Thomas Engel and introduced commercially in the late 1960s.
There are three types of PEX: PEX-A, PEX-B and PEX-C. The most common, PEX-A, is the best choice for most residential applications. It’s flexible, has little coil memory and can be easily repaired with a heat gun. It has also been in service for 50 years with few publicly known issues. Its downside is a higher rate of chemical leaching than the other two types.
Other types of PEX have a lower rate of leaching, but they are less flexible and aren’t recommended for plumbing applications, especially because they can be difficult to repair once they have a kink. Generally, the best option is PEX-B, which uses the silane method of cross-linking and is less costly than PEX-A. PEX-C is the least popular type, since it’s more expensive and has a higher rate of chemical leaching than either PEX-A or PEX-B. pex tubing