• Share:
Plumbing with PEX Tubing

Long used in radiant heating systems, flexible PEX tubing is perfect for water supply lines because it’s easy to run through walls and floors and simple to work with.

By the DIY experts of The Family Handyman Magazine

The advantages of PEX

PEX, a flexible tubing that comes in long rolls or sticks, offers many advantages over traditional piping. First, you can usually make long continuous runs, eliminating most elbows and joints. You can snake long runs through joists and studs, eliminating most elbows and joints. Second, PEX doesn't sweat under high humidity conditions, and it's resistant to bursting, even if the lines freeze solid. Third, joints are easier. You add fittings simply by crimping metal rings over barbed fittings using a special crimping tool. Crimping takes seconds and is virtually error-free, avoiding the hassle of soldering (copper) and the fumes and mess of cementing (CPVC). Finally, it's super easy to work with, and it's less expensive than copper.

Check with a local plumbing inspector for local requirements and read the manufacturer's directions, which may vary slightly from what we show here.

Step into just about any house built in the past 50 years, and odds are, you're going to see one of three materials used for the water supply lines: copper, steel or CPVC. While these three materials are reliable and fairly easy to work with, a flexible tubing called PEX (“cross-linked” polyethylene) has become popular with many plumbers. PEX has been used for many years for in-floor heating systems but only more recently for supply lines. You may find it in a newer home, and, since it's easy to work with, you might consider it as an alternative to traditional materials when running new water lines. It's now available at many home centers. In this article, we’ll introduce you to PEX and show you the basic techniques for working with it.
Different brands of PEX

Different brands of PEX

Use the Same Stuff

There are several different manufacturers of PEX. It is very important that you know which brand of pipes you’re working with and install only that manufacturer’s connectors and fittings. If you mix and match materials, you will void your warranty and may fail your inspection. Worst-case scenario: You’ll end up with leaky pipes, water damage and extremely unhappy homeowners. Not all products have recognizable markings on them, so leave a few of the packaging labels on-site to appease the inspector and for future reference.

Make crimped joints at fittings

The heart and soul of the PEX system is the barbed fitting/crimping ring combination (Photo 2). There’s no need for solder, glue or pipe wrenches—just position the crimping ring over the end of the PEX pipe, slide the pipe over the barbed fitting and use the special crimping tool to compress the ring. Just be sure to center the ring over the barb and depress the crimping tool's handles completely.

That's it. The resulting seal is watertight. The crimping tool shown can be used for both 3/4-in. and 1/2-in. crimps, important when you're running several sizes of pipe. If you make a mistake in crimping, you can use a special decrimping tool to remove the ring and then reuse the fitting. A clean, square cut is essential for a proper seal; the PEX cutter shown in Photo 3 works great and is available anywhere PEX is sold.

Another type of fitting for joints, called “stab-in” fittings (Photo 4), is also available. You simply push the ends of the PEX into the fitting, where it locks in place. These fittings are available for most situations, including joining PEX to copper and to CPVC.

Cinch clamps

Cinch clamps

Cinch Clamps

Another popular and widely used clamp is the cinch clamp. They’re readily available and relatively inexpensive, and you know when they’re installed properly because the tab of the clamp will be visibly pinched.

Fittings for a shower valve

Most shower valves have threaded ports for the supply lines. Tighten the threaded fittings into the shower valve before crimping on the PEX line. Then run the lines through the studs (Photo 5), make 90-degree turns with a plastic or metal elbow sleeve, or crimp in right-angle fittings in tight quarters (Photo 12). Splice in shutoff valves as well (Photo 6). Then, install “drop-ear elbows” to stabilize the spouts and/or showerhead assemblies, just as you normally would (Photo 7). Once you've secured your drop-ear elbows and threaded fittings, run the PEX line between the valve and the drop-ear elbows and crimp each joint.


PEX is plastic, and plastic melts. So keep your PEX pipes away from hot stuff. Codes commonly require PEX to be at least 18 in. away from the water heater and 6 in. away from single-wall flues on gas water heaters. And stay well clear of furnace flues, wood-burning stove pipes and any other item that gets hot.

Since PEX won't burst when it freezes, you might be tempted to use it for seasonal dwellings, such as cabins. PEX is soft, however, and rodents could chew through exposed lines.

Repair or replace kinks

Protect PEX with abrasion clips and insulation.

Protect PEX with abrasion clips and insulation.

Abrasion and suspension clips

Abrasion and suspension clips

Protect Your Pex

PEX expands and contracts with changes in temperature, which causes the pipes to move back and forth. Several years of even the slightest movement can wear a hole in PEX pipes, especially if they're rubbing against something abrasive.

If your pipe is in contact with a joist, duct, electrical box or steel stud, or it is passing through a block wall or concrete slab, it needs to be protected. You can protect your pipe with abrasion clips, cover the pipe with inexpensive pipe insulation, or enclose it with a larger pipe. Pipes that are encased in concrete (for in-floor heating, for example) are OK because the concrete holds them in place. And pipes running straight through wood studs and joists are fine too—just protect the pipe in areas where it bends as it passes through.

Transitions to other types of pipe

If you're adding a guest bath or finally getting to that laundry tub you've been promising for the past five years, you'll have to join PEX to the existing system. Make sure you shut off the main water supply, then drain the lines. Use the special transition fittings shown to transition from copper, CPVC or steel. Solder, glue or thread on the transition fitting, then crimp PEX line on the barbed fitting. Note: Plumbing codes vary on allowing brass/steel connections. If they're allowed, be sure to apply liberal amounts of both Teflon tape and pipe joint compound to prevent reaction between the two metals.

Run the line without joints

You can run PEX line a couple of different ways. Most often, you run PEX as you would in a conventional plumbing system, with 3/4-in. main lines and 1/2-in. branch lines (Photo 1). You can also use a “manifold” system, where you run a 1/2-in. line to each fixture from a central spot. But we won't show that system here.

Run your main lines first—don't worry about cutting in your branch lines yet. If you're running PEX through joists or studs, drill 3/4-in. holes for 1/2-in. piping and 1-in. holes for 3/4-in. piping. You don't have to drill holes in an exact straight line; there's enough flex in the pipe to feed it through misaligned holes. Have a helper feed the line to avoid kinks and snarls (Photo 9). Where the pipe runs along a surface, be sure to support it every 16 to 24 in. to reduce sag and give the piping a neat appearance (Photo 10). Some manufacturers recommend adding “suspension clips” at each hole to prevent abrasion. You must use suspension clips for PEX that goes through metal studs, and nail protection plates when the tubing runs within 1-1/2 in. of the face of a stud or joist.

You can generally flex PEX into gradual bends without risking a kink (Photo 10). When you need to turn a corner, many times you can bend the pipe manually and eliminate the need for an elbow. But different brands of PEX have different “kinking” points, so always read the manufacturer's guidelines. Buy special plastic or metal elbows (Photo 5) to make the tightest recommended turns virtually kink-proof.

If you need to make a really sharp turn, cut the line and use a copper 90-degree ell (Photo 12).

Home runs for supply lines.

Home runs for supply lines.

Home Runs Are Best

You can install PEX with main lines and branches to each fixture, but “home runs” are better. A home run is one line that runs directly to a fixture, starting at a manifold (above). Home runs require more piping but deliver a stronger and more consistent water flow. Also, installing home runs is fast and requires only two connections (one at the manifold and another at the fixture end), which reduces leaks.

You can also use a hybrid system where you run 3/4-in. hot and cold lines to a set of fixtures—for example, in a bathroom—and install a smaller manifold behind an access panel. Then make short runs of 1/2-in. lines to each fixture. Another cool thing about home runs is that each fitting has its own shutoff at the manifold. That means you can shut off just that fitting to do some work—you don’t have to shut off the water to the whole house.

Upsize to avoid poor pressure

Keep PEX coiled with bungee cords.

Keep PEX coiled with bungee cords.

Control Your Coil With an Elastic Cord

One complaint about working with PEX is that the coils have a mind of their own. As soon as the banding is removed from the coils, they tend to explode out in every direction. To deal with this, use bungee cords to help keep your coils in check. Leave the cords on and unroll just the amount you need. If your coil comes wrapped in plastic, don’t remove it. Sometimes you can just feed out pipe from the innermost section of the coil. If you have just a few smaller runs or short lengths to install, buy sections of straight pipe—it's a lot easier to work with.

Warm up cold pipes

Plan for stub-outs in advance

There are a couple of options for bringing PEX out through a wall (stub-outs). If the piping is going to be exposed, say for a pedestal sink or a toilet, buy a copper stub-out and crimp it onto the PEX (Photo 11). Then use standard shutoff valves. If the stub-out will be hidden, inside a cabinet, for example, or you don't mind the look of exposed PEX line, use a barbed PEX shutoff valve with an elbow (Photo 12). You can also run PEX directly to the fixtures (see photo).

Whichever method you use, be sure to add a couple of extra fasteners next to the stub-out to increase stability.

Metal bend support

Metal bend support

Plastic bend support

Plastic bend support

Avoid Kinks at Tight Corners

PEX's flexibility makes it easy to work with. It can be bent around pretty sharp corners without the need for an elbow fitting. But if you try to bend it too much, you’ll end up kinking it. Installing a bend support will prevent this, and it will also protect the pipe from abrasion.

Back to Top

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

    • Cordless drill
    • Adjustable wrench
    • Plumbers tape

You'll also need a PEX crimper, cutter and decrimping tool for the brand of PEX that you buy.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • PEX tubing
    • PEX fittings and transitions
    • PEX shutoffs
    • PEX support clamps
    • Bungee cords

Comments from DIY Community Members

Share what's on your mind and see what other DIYers are thinking about.

1 - 10 of 10 comments
Show per page: 20   All

April 05, 9:03 PM [GMT -5]

The crimper I used (both for 1/2" and 3/4") was too much for my petite hands. I'm a strong gal but needed a beefy guy to complete this project. I never had that problem with copper. But then, it took twice to three times as long to complete!

I just wish ratcheting crimpers could be created like the ratcheting cutter. Women are spending more and more time on home improvements and the manufacturers should pay attention.

September 26, 1:51 PM [GMT -5]

I read the article in the magazine and checked this story online, but no mention of heating system use; that should have been included. Can you use PEX in heating systems like hot water/radiator?

September 13, 4:03 PM [GMT -5]

I'm considering using PEX. I have a baseboard hot water heating system. Can I use PEX for that system that is supplied hot water from a boiler?

March 17, 2:50 PM [GMT -5]

It is very informative for new kind of plumbing pipes. Good job.

March 14, 1:39 PM [GMT -5]

I have been using a snap on type of connector for repairing and adding to the pex in a cottage we bought. seems to work just fine.

January 22, 9:30 AM [GMT -5]

I had all three solutions I had a house and replaced all (yup all) of the plumbing replaced with copper.. then built a new house and used all CPVC.. I recently replaced everything (yup all again) with PEX ... i also have the pex manifold .. I have one for cold and another for hot. You have a separate large copper 1 inch to the manifold and then all the pex runs to each outlet... After using pex I won't use anything else.. You need afew special tools if you're going to do it yourself you'll find installation to be a breeze and you don't have to worry about leaks.. I replaced all the valves with quarter turn ones.

December 04, 10:38 PM [GMT -5]


November 20, 5:24 PM [GMT -5]

This isnt entirely true that its used in radiant heating systems. Pex-A is used in radient floors. But even then its suppose to be heat pex not aqua pex.

Also Pex-A can be expanded and also heated to fix kinks. Pex-B and Pex-C can not. Pex C fittings are usually crimp style fittings. The bad part about crimp is it restricts flow because the fitting is inserted into the pipe. While expansion pex, expands the pipe and ring and then the fitting is inserted in that has the same inside diameter as the pipe.

November 03, 5:56 PM [GMT -5]

For tight places you can use a pocket crimper.


November 01, 2:14 PM [GMT -5]

I like using pex, but one of the biggest disadvantages I have is using the crimper in tight spaces. For example uder the kitchen sink. I was putting in a new sink and had to redo all the lines because there wasn't room for the crimper without starting from scratch. The only way around it was to use a battery operated crimper and those cost thousands.

+ Add Your Comment

Add Your Comment

Plumbing with PEX Tubing

Please add your comment

Log in to My Account

Log in to enjoy membership benefits from The Family Handyman.

  • Forgot your password?
Don’t have an account yet?

Sign up today for FREE and become part of The Family Handyman community of DIYers.

Member benefits:

  • Get a FREE Traditional Bookcase Project Plan
  • Sign up for FREE DIY newsletters
  • Save projects to your project binder
  • Ask and answer questions in our DIY Forums
  • Share comments on DIY Projects and more!
Join Us Today

Report Abuse

Reasons for reporting post

Free OnSite Newsletter

Get timely DIY projects for your home and yard, plus a dream project for your wish list!

Follow Us

Featured Product

Buy Now