The name isn't very catchy, but PEX-AL-PEX has the benefits of both metal and plastic pipe.

I was first introduced to a multi-layer PEX-AL-PEX pipe about 15 years ago. A company executive explained to me how the pipe was made and how they planned to distribute it in North America. What kept running through my mind at the time was what is this good for?

When I couldn't hold back any more, I finally blurted out, "Why would somebody want a pipe like this?" I could see the hurt look in the executive's eyes. I went on to explain that it was not my intention to insult him, I was just curious as to why a contractor would want to use this type of pipe. I went on to say that if a contractor wanted metallic piping they would use copper, and if they wanted plastic pipe, they would use plastic pipe.

His eyes lit up as he quickly responded, "Don't you understand, with PEX-AL-PEX, you get the best of both worlds. There is the high quality of a corrosion-resistant PEX plastic pipe on the interior, and the rigidity of a metallic pipe with the aluminum inner layer."

It quickly made sense to me that there could be a market for this product. PEX has been established as one of the highest quality plastics for use in potable water systems. Hence, the water is in contact with this high-quality plastic. However, unlike PEX, when you form the pipe, it stays in place. One of the complaints I always hear from contractors is that a PEX installation looks like spaghetti. Others say that the plumbing looks like an electrician installed it.

With PEX-AL-PEX, the aluminum inner layer keeps the pipe rigid, as if it were a metallic piping system. Unlike metallic pipe, it can bend easily in your hand and take the shape you determine. Hence, elbows and 45's are unnecessary fittings. The feel of the aluminum also assures that the bends do not exceed the bending radius of the pipe.

True Benefits

PEX-AL-PEX got its start in North America in radiant heating systems. It is an excellent material for this application, since the pipe retains its shape. When PEX is used, additional pipe supports are required to hold the pipe in place until the concrete or gypcrete is installed.

Lately, the PEX-AL-PEX manufacturers have been pushing to use the pipe in potable water distribution systems. Who has not seen the clever IPEX ads that ask, "Where's my Kitec?"

PEX-AL-PEX has the same material exposed to the water as PEX. Hence, it would only be natural that if PEX is acceptable for potable water piping systems, so is PEX-AL-PEX. The plumbing codes are finally catching up to this concept. PEX-AL-PEX is currently permitted for potable water in the International Plumbing Code. The material is also listed with the Uniform Plumbing Code.

Another question on contractors' minds is, "How do we join the pipe?" There are two popular methods of joining PEX-AL-PEX. One method uses a crimp fitting, the other a compression fitting. Both fittings are insert-type fittings. The crimp fitting requires a crimping tool, while the compression fittings are made with normal wrenches. Most of the manufacturers have o-rings as part of their fittings. This is to ensure the most positive joint for the piping system.

The newer crimp and compression fittings are now interchangeable between manufacturers. Previously, the fittings were tied to the particular manufacturer of the pipe.

While IPEX's Kitec pipe has been one of the standard bearers in the PEX-AL-PEX business, there are other manufacturers introducing their versions of the pipe. This is a strong indicator that the material is starting to catch on with contractors.

One of the new PEX-AL-PEX pipes available is from Stadler-Viega. They have a very clever concept in that the color of the pipe is copper. Rather than using fittings similar to other PEX-AL-PEX pipe, Stadler-Viega has a tool that peels away the outer layer of PEX and the layer of aluminum. The fittings used are the standard PEX press fittings used for the company's PEX pipe. The idea is to have only one set of fittings for both their PEX and PEX-AL-PEX pipe.


The one system I do not recommend for PEX-AL-PEX is a home-run style manifold piping system; PEX is known as the piping system for this style of manifold system. PEX-AL-PEX is not as flexible to accommodate this type of installation. PEX-AL-PEX is really intended for conventional straight-piping systems or within the slab.

Another concern is that PEX-AL-PEX has not been listed for residential sprinkler systems. However, that could change. As combined residential sprinkler systems gain in popularity, PEX-AL-PEX will need a listing to stay competitive with other piping systems.

I haven't found any other real downsides to the material. A major factor to consider is whether you want a rigid pipe or a flexible pipe.

The one complaint I do have is in the name of the pipe. PEX-AL-PEX is a mouthful. I think they should have come up with a better name or simpler acronym. Perhaps just shortening the name to PAP pipe would be preferable. Maybe if everybody started calling it Pap pipe, it will catch on. Or, how about layered pipe? Anything is better than PEX-AL-PEX.

In the meantime, the way I see it, the PEX-AL-PEX market is a growing market. The use of this type of piping material is expanding across the country. If you haven't tried it yet, give it a shot. It really does offer the best of both worlds.