PEX: The new Knob & Tube – A Home Inspection will help


What is the concern?

Apart from incorrect installation, where pipes have been bent beyond their allowed installation radius, or they have been scratched, or subjected to chemical solvents the piping itself is adequate for normal residential and commercial installations.  The piping itself, unless made with a Ultra-Violet barrier such as that in the picture of the coil of Red PEX below, degrades when exposed to sunlight.

The main problem with PEX comes from the fittings that are used to connect it together, and to create branches to other segments of PEX.  Most of the fittings are made of Brass, which is an alloy made primarily of Copper and Zinc.  Zinc is a highly reactive metal with a weak atomic bond.   A professional Home Inspector will help determine if there is a concern with the fittings during a Home Inspection.

This is not normally a problem, until you start pushing water, especially water that has high levels of carbonates, oxygen, chlorine or fluorine in it.  (Hard Water or water treated by the water utilities)

What this does is leach the zinc out of the brass, a process called dezincification, leaving behind two problems.

Zinc Oxide buildup (Merigue Dezincification)The first problem with dezincification is that a white Zinc oxide coating builds up inside the pipes, called meringue dezincification, that gradually clogs the pipes, much like plaque reduces the width of hardened arteries.

This clogging creates “low pressure” at the faucets.

Some plumbers and inspectors may tell you that it creates high-pressure in the pipes, but this is not so.  The pressure in the pipes will not exceed that of the supply in residential potable water or the pump in a hydronic radiation heating system (hot-water and radiators).

ThCorroded brasse second problem is dezincification leaves behind brass that is corroded and has areas that consists of degraded (porous) brass and loosely bonded copper, this is the copper that is left in the brass after the zinc has left it.

If you look at brass, that has had the zinc leached from it, under a strong microscope, (the picture on the right) it would, near the surface, resemble a mountain range (this is at the top of the picture) and further into the brass it looks more like a map.

In this map however, the black parts are areas of porousness, which means water can penetrate, and the area is prone to complete failure.

This is what has happened to the pipe in the picture on the left, although luckily this complete failure happened during an investigation into a much smaller leak.

This is generally not an issue where the piping is visible as the corrosion can be seen and the parts replaced before they fail.

With PEX piping, the majority of the brass fittings are hidden behind walls, floors and ceilings. This means that when the corroded fittings are combined with increased water pressure from the Zinc Oxide blockage, they can leak and fail completely and because they are not visible the leak that occurs can be catastrophic.

There are two types of Brass found in residential water fittings, Yellow-Brass which has a 35% volume of zinc to copper, and Red-Brass which has less than 15% zinc to copper.  Under the right conditions, the Yellow-Brass will fail, due to de-zincification, over twice as fast and more catastrophically than the Red-Brass under the same conditions.

There is also Admiralty-Brass which has tin added and dezincification resistant brass (DZR Brass) which has arsenic added.  Both brasses are to stabilise them from the loss of Zinc but with tin and arsenic being toxic, they should not be used in potable water supplies.

What is PEX?

PEX stands for cross-linked polyethylene, meaning the tubing is resistant to the adverse effects of hot and cold temperatures. The cross-linking occurs through a chemical reaction between the polyethylene within the piping, the result of which is a flexible, resistant tubing.  It was developed for use in Europe during the 1970s, PEX piping was first introduced to the North America in 1980.

The main use of PEX piping is in a water system. This is due to the temperature resistance as well as chemical resistance. The piping can be used in residential or business properties. PEX piping is designed for indoor and underground use. Exposure to direct sunlight will cause damage to the pipes, rendering the system unusable outdoors.

PEX-AL-PEX PipeThree types of PEX constructions exist, normal PEX (which is known as barrier-less-PEX) and PEX-AL-PEX and Oxygen Barrier PEX (which are both known as Barrier-PEX).

Some applications require PEX with added oxygen barrier properties. Radiant floor heating (or hydronic heating systems) may include some ferrous (iron-containing) components which will corrode over time if exposed to oxygen. Since standard PEX tubing allows some oxygen to penetrate through the tube walls, various “Oxygen Barrier PEX” tubing has been designed to prevent diffusion of oxygen into these systems.

PEX-Al-PEX (or PEX-Aluminum-PEX or “PAP”) is a specialty PEX tubing manufactured by several suppliers. This tubing has a layer of aluminum embedded between layers of PEX to provide an oxygen barrier. PEX-AL-PEX may also be called multi-layer pipe or composite plastic aluminum pipe. PEX-AL-PEX will also retain shape when bent, and may also exhibit less expansion and shrinkage during temperature fluctuations, but may be less flexible than PEX tubing. PEX-AL-PEX costs about 30% more than standard PEX. .

Oxygen barrier PEX has a layer of polymer laminated to the outside surface (or sandwiched internally between PEX layers) that prevents oxygen from penetrating. The polymer film is usually EVOH (ethyl vinyl alcohol co-polymer), used in the food industry as an oxygen barrier.

A Home Inspection will help you identify it.

PEX-Markings

All PEX and PEX-AL-PEX has a standard set of markings.  These are printed along the length of the pipe at regular intervals.  There have been recent changes in the markings, but the location of each of the markings in relation to the start of the repeated printed block is the same.

The diagram below gives an idea of the sort of information that is printed on the sides of PEX tubing types.  It gives an inspector an idea of what the pipe is rated for, and where it should be installed.

PEX_Markings_legend

 

What are the remedies?

If you search through the internet, the majority of plumbers that have picked up on this issue will tell you that the only cure is to re-plumb the entire house.  This is obviously a very expensive remedy, so lets take a pragmatic look at what options there might be.

First, the pipes themselves haven’t necessarily failed.  PEX piping has a life expectancy of between 25-30 years (depending upon Manufacturers information).  If your house was plumbed with PEX between 1995 and 2007 the plumbing will only be (dated as at publication) 5-17 years old, so the piping should be well within it’s life-expectancy.

Second, if you do not live in a hard water area, or an area that has high level of oxygen dissolved in the water, or an area where the local water authority treats the water with chlorine and/or fluorine then the rate of corrosion is going to be less.

If you do have suspect fittings, then it is only the fittings that are the problem, and not, until they reach end-of-life, the pipes.  So why go to all the expense of tearing down all the walls to expose and replace all the pipes, when it is only the fittings that need replacing, and these could be done in a piece-by-piece fashion?

Again, plumbers will likely tell you that it is impossible to find the fittings so tearing open all the walls is the only way to go.  Again, I disagree.

From the perspective of a plumber it might make good business sense, but we have had metal detectors for many years that are capable of finding metal components buried under many types of material, finding a corroded brass fitting behind drywall should not pose too much of a problem.

Confirming the existence, of the fittings, also need not require ripping a whole wall out, using a small hole and a bore-scope can identify the exact location of a fitting.  Cutting open a small portion of drywall and fixing just the area of piping at issue, to me makes way more sense from an economics point of view as a home owner.

PEX pipes are designed to be cut and joined, if they weren’t we wouldn’t have the problem in the first place.  Cutting an offending fitting from a section of pipe, and replacing it with a new section and non-corroding fittings makes more sense to me than tearing half the house down to replace perfectly good piping.

The problem comes when there are specialised wall treatments.  This is a situation where, perhaps, patching a wall to make it look right is difficult or is going to prove cost-prohibitive, then re-walling may be the logical choice, but it’s doesn’t have to be the de-facto approach, and I would recommend consulting a dry-walling specialist in addition to a plumber before making a decision.

So is there a concern?

As always, the concern is that the insurance companies might get on the band-wagon and start to increase premiums to properties that have PEX with Brass fittings.  While this is possibly justified, as these properties do have a higher than average chance of water leaks, the insurance companies do tend to go overboard.  Look at UFFI, Knob & Tube and Aluminum wiring as prior examples.  All of these component installations have been proved, over and again, that installed correctly, and not tampered with, they are adequately safe to pose no greater threat than non-UFFI insulation, and copper wiring.

If insurance companies implement an across-the-board policy that raises PEX/Brass installations, then it will no doubt have a dramatic effect on property values and the cost of remediation.

Problems to date.

There have been several law-suits, both class-action and individual, to date that have targeted companies that manufacture PEX pipe and fittings and contractors that have continued to install these fittings after the problems were first advertised.

I will attempt to keep up to date with the issues and post them to this site, so you may want to return to check for more links.

Manufacturer Component brands Comments
IPEX Inc of Canada, brand name Kitec. Kitec, PlumbBetter, IPEX AQUA, WarmRite, Kitec XPA, AmbioComfort, XPA, KERR Controls or Plomberie Améliorée See more on this site here
To be eligible to receive compensation from the Kitec settlement, you must complete and submit a valid Claim Form within 8 years after the Effective Date. As of now, the estimated deadline is January 20, 2020.  Check the Kitec Settlements administrators website here
Zurn Pex Plumbing systems QPex See more on this site here
This has only been raised as a class action suit in the U.S.  more information can be found here.  It is not know the amount of Zurn Pex systems that have been installed in Canada.  Zurn stopped selling brass fittings in 2010 and now only supply plastic fittings.
Plasco and Uponor Inc. P Pex, MB Pex This lawsuit is currently only held in Minnesota in the U.S. and is awaiting a decision as to whether it will achieve class-action status.  More information can be found here

Update Jun 6, 2016:   A Canadian class-action lawsuit has been approved and more details can be found here

Rehau Everloc No information yet
Tradesmen supply PEXCaliber No information yet
Wirsbo ProPEX No information yet
Vanguard CrimpSert No information yet

Viaega make PEX fittings of Copper and Bronze that are sold under the ProPress, CombiFlex and PureFlow brand names.  These do not suffer from the same problems as Brass fittings.

Why use PEX in the first place?

There are several advantages to using PEX from both a builders and homeowners perspective.

  • Flexible PEX tube is manufactured by extrusion, and shipped and stored on spools, where rigid plastic or metal piping must be cut to some practical length for shipping and storage. This leads to several advantages, including lower shipping and handling costs due to decreased weight and improved storage options.
  • PEX plumbing installations require fewer fittings than rigid piping. The flexible tubing can turn 90 degree corners without the need for elbow fittings, and PEX tubing unrolled from spools can be installed in long runs without the need for coupling fittings.
  • Attaching PEX tube to fittings does not require soldering, and so eliminates the health hazards involved with lead-based solder and acid fluxes; PEX is also safer to install since a torch is not needed to make connections.
  • PEX resists the scale build-up common with copper pipe, and does not pit or corrode when exposed to acidic water.
  • PEX is much more resistant to freeze-breakage than copper or rigid plastic pipe.
  • PEX tubing does not transfer heat as readily as copper, and so conserves energy.
  • Water flows more quietly through PEX tube, and the characteristic “water hammer” noise of copper pipe systems is virtually eliminated.
  • PEX plumbing installations cost less because:
    • PEX is less expensive than copper pipe.
    • Less time is spent running pipe and installing fittings than with rigid pipe systems.
    • Installing fewer fittings reduces the chances for expensive callbacks.

 

Update Jan 14, 2016:   PEX was introduced into North America in 1980.  The average life expectancy for PEX is between 25 to 30 years.  If you have a home that was built before 1991 and it has the original PEX it may be time to call a plumber to investigate the likelihood of a PEX replacement.   Remember, PEX is a plumbing component that carries, normally pressurised, water.  Unlike pin-hole leaks in copper and galvanised piping, when PEX fails, it generally fails catastrophically.    This is one time when you maybe should err on the side of caution to ensure your home, and your finances, are protected.