Installing PEX Tubing: An Overview

PEX tubing is a great choice when running water to new fixtures, remodeling, or even repiping. Installing PEX does not require glue or soldering; instead, it uses fittings that require cinch clamps or copper crimp rings that hold the pipe onto the fittings. There are also push-fit fittings that can be used when installing PEX. They do not require any clamps or PEX tools, but they can get pricey very quickly.

The fact that PEX tubing comes in really long rolls makes it quicker to install because there are fewer fittings to connect. If you are thinking of installing PEX tubing, the two main challenges are getting the necessary tools and finding the right fittings needed for the job. Most local hardware and home improvement stores will carry a nice selection of PEX fittings, but double-check this before you plan any big projects.

Installing PEX Tubing

  1. Plan: Figure out what type of project it is, how much pipe, how many fitting you need, and anything else you may require. If you are doing only a few fittings, you can make it quick by using the push-fit fittings such as Sharkbite. This will not be cost-effective, however, if you have more than a few fittings to install as with a small remodel or similar bigger job. Will you be using manifolds? This is an installation where everything is run from the manifold to the fixture with no fittings in between (called home runs). This type of installation can be great because everything can be shut off and isolated from one location, but it requires many more times the amount of pipe than when just branching off with tees such as copper or CPVC.
  2. Collect all materials: It helps to draw out a diagram of how the pipe will run and where fittings will be necessary. Make a list of fittings taking care to not forget shut-off valves at the sinks and toilets. Angle stops and straight stops can come with the PEX end, so you can use the clamps or rings to make the connections. They also come in push-fit styles, but they are more expensive. Extra clamps or crimp rings are always a good idea in case any mistakes are made. Clamps and supports for the PEX tubing will be necessary. If connecting to a water heater, the PEX cannot be within 18 inches of the water heater, so an 18-inch water heater flex line can be used as the transition into the water heater.
    With list in hand, call or head out to get the fittings and pipe length that you need. Have the basics of what you have in mind and your diagram handy because the stores may or may not have all of the fittings you want. It may be necessary to make slight changes or adjustments. Order or purchase all materials ahead of time.
  3. Run the PEX tubing: PEX needs to be supported a minimum of every 32 inches when running horizontally. If running vertically, it should be supported every 4 to 6 feet. (These supports are critical.) The straps should be plastic or metal that is designed to work for plastic pipe. PEX is not meant to be pulled tight, so leave slack for expansion and contraction. Coming out of the wall to the fixtures, you can use a PEX to copper stub out or another type of PEX support such as drop-ear bend support. From under the sink, you can use a shut-off valve like an angle stop then a flex line to the faucet or toilet. If this is a tub or shower, you can hook directly to the valve with PEX to iron pipe adapters into the valve.
  4. Clamp: Make sure to use the right clamps and tools together. If you have the cinch clamp tool, you will need to use only cinch clamps. Slide the clamp or crimp ring onto the pipe then slide the pipe onto the fitting all the way. Position the clamp or crimp ring at between 1/8 inch to 1/4 inch away from the end of the pipe, and use your tool to tighten the clamp or ring. A gauge is often provided, so you know if the crimp ring is compressed onto the fitting. Visually inspect to see that all the joints have clamps or crimp rings on all sides of the fittings because forgetting to tighten a clamp or leaving one side of the fitting with a crimp ring missing is a common mistake.
  5. Test: Turn the water on, and inspect each fitting for leaks. If any leaks occur, you may have to remove the fitting and use new crimp rings or clamps. They do make a crimp ring removal tools that can make removing a PEX ring easier, or you can carefully grind off the ring or cut it with a small hacksaw. When the fittings are re-installed, check for leaks again and then once again after a couple of hours.