Maintenance and Repairs

April 15, 2024 Published by Golden Horseshoe Chapter - By Brad Gascoigne

Epoxy Pipe Lining: A Retrospective

From the Volume 19, Spring 2024 issue of the CCI GHC Condo News Magazine

Every now and then, a new product appears in the construction market that has the potential to shake up the industry. Some become very popular, but ultimately fail to live up to expectations and then vanish. That seems to be the story with epoxy lining of domestic hot water systems in the GTA. It gained a foothold in the market 15-20 years ago as an alternative to replacing domestic water piping reaching the end of its service life. It became quite popular, especially in the condominium market, but as problems with the systems began to manifest, the industry suddenly collapsed and disappeared within a few short years, leaving behind problems and warranties not worth the paper they were written on.

To find out how that all happened, we really need to go back to the beginning: It all starts with so-called ‘pinhole’ leaks. Highrise buildings employ a hot water recirculation system that constantly moves hot water from the boiler plant, through the piping network and back to the boiler plant to be reheated. This is ongoing, 24/7/365. The setup allows for effective on-demand hot water in the building at any time of the day or night since there is reheated water in the piping at all times. Without a recirculation system, hot water would sit stagnant in the piping system and cool off during times of low usage, requiring water to be run for many minutes until hot water arrived at a unit in the middle of the building.

The result of the constant circulation through the piping system is wear and tear on the piping. At areas of high turbulence in particular, the flowing water effectively erodes the interior walls of the pipe, thinning the pipe until it can no longer hold the pressure of the water, and a pinhole leak occurs.

After repeated pinhole leaks, something needs to be done with the piping. The traditional solution to pinhole leak repair is to replace the affected section(s) of piping. On a building-wide basis, this means a re-pipe, or a riser replacement within the building. As the vertical pipes are concealed behind walls and are usually in kitchen and bathroom areas, the result is removing interior finishes and possibly tiles, appliances and cabinetry to access and replace the piping. It is very costly and disruptive and no building seems to be designed with easy access for piping replacement in mind.

Epoxy lining seemed to offer a better alternative: instead of replacing all of the piping, just reline it. The benefits for condominium buildings was obvious: it promised to be faster, cheaper and less impactful than traditional piping replacement. There were no holes needed in residents’ walls. Kitchens and bathrooms remained intact. There were fewer disagreements over upgraded finishes, and the various companies offered big, 20+ year warranties on the systems.

At the height of the trend, dozens of buildings were being lined every year in the GTA. There were multiple companies in the GTA providing pipe lining services; a whole industry had arisen.

While each company had proprietary epoxy and slightly different application processes, ultimately it came down to the following general procedure: (1) the riser was drained, and dried; (2) the interior of the riser was ‘prepared’ via a form of sandblasting (this should be red-flag no. 1…); (3) a quantity of epoxy is mixed depending upon the diameter and length of the section of pipe being lined (this should be red flag no.2…); and (4) the epoxy is blown through the section of pipe with compressed air, coating the pipe walls, and then allowed to cure.

Though precise figures are not available, it is likely that tens of thousands of linear feet of pipe were lined in dozens, if not hundreds of buildings across the GTA. Fast-forward 15 years, and the entire epoxy lining industry has disappeared from the GTA, and an increasing number of buildings are being plagued with issues. So what may have gone wrong?

Coatings are nothing new. They are used everywhere in the construction industry, from paints to waterproofing systems. Anyone who reviews coatings professionally quickly learns that one of the most important technical aspects is proper surface preparation. If the coating does not bond well to the substrate, it will not last. This brings us back to ‘red flag number 1’: although the interiors of the pipes were ‘prepared’ via a sandblasting process, there really was no practical way to review the adequacy of the preparation prior to the epoxy coating. It was all hidden within the pipes. All that could be done was to obtain a cut section of the lined pipe after the epoxy was installed and qualitatively test the adhesion of the epoxy to the pipe. One cut section is a very small sample size on a multi-story riser, and if a problem was identified, it was too late.

Another important technical consideration with coatings is achieving the proper thickness. Here is where red flag number 2 comes in. Any product that requires measuring and mixing onsite based on fuzzy math is probably prone to error. If the incorrect amount of epoxy is injected, the resulting coating layer may be too thick or too thin, which could impact longevity. Pipes can also offset (or jog around) unexpectedly within the building, resulting in unaccounted-for lengths of pipe. Cut pipe sections can help here too by allowing a review of the coating thickness, but again, this is a small sample size, and if there is an issue, it is already too late.

There are also secondary problems. One of the main drawbacks to epoxy lining is repairing or modifying the pipe in the future, if needed. It is not possible to solder to epoxy-lined pipe because the heat from the blow torch damages the epoxy. This leaves push-to-connect and crimp-type fittings as the only options. Neither of these options are as robust as a soldered joint, and each has its own additional problems. Push-to-connect fittings really should not be buried behind finishes and seem prone to failure in hot water recirculation systems. Installing crimp fittings slightly deforms the copper pipe, which can crack the relatively brittle epoxy lining inside, causing further issues.

In our experience, failure of the epoxy lining system usually manifests when the epoxy lining debonds from the internal pipe walls, causing lining fragments to travel in the stream water throughout the piping system. Epoxy debris gets caught in appliance filters and tap aerators, causing chronic water flow restrictions. In some cases, debris can obstruct entire risers, affecting water delivery to the units. A lot of buildings initially opt to deal with these issues on a case-by-case basis by replacing affected sections of the epoxy-lined pipe as they develop.

With the pipe repair challenges noted above, there is not a good method of dealing with repairs on a localized basis. Ultimately, the only way to get the epoxy out of the system is to remove the lined pipe and replace it with new copper piping.

Fortunately, not every building that had its risers lined has experienced issues. For the condominiums that have been unlucky, they can start to see the failure of the epoxy system within 5 years of it being installed, a far cry from the 20+ year warranty promised. These condominiums are facing continuous issues with the functionality of their domestic hot water system, increased and unexpected plumbing repair costs, and they are ultimately facing a major plumbing riser replacement program far sooner than expected, impacting Reserve Fund Study budgets and timings.

For condominiums that have been fortunate and have not seen widespread issues with the epoxy lining, an end-of-life strategy for dealing with the epoxy needs to be considered. Will the building deal with future epoxy lining failures on a case-by-case basis, or proactively replace the risers? Given the large number of failures in the industry, it is prudent to assume the epoxy lining will not achieve the promised service life, and to plan for an earlier riser replacement in the RFS. Have these conversations with your consultant and reserve fund planner.

In hindsight, the whole epoxy lining process seems prone to issues from a quality control perspective. There was simply no way to practically carry out effective quality control review inside the pipes during critical stages of the lining process, leaving buildings susceptible to workmanship errors that could greatly impact the longevity of the system. Unfortunately, once problems do develop, there is no easy remedy.

Brad Gascoigne, B.Arch.Sc., BSS is the Principal, Building Science at Brown & Beattie Ltd., a building science engineering firm dedicated to providing clear and sensible building improvement, maintenance, and repair planning advice by listening to clients’ objectives. Mr. Gascoigne holds a Bachelor of Architectural Science in Building Science from Ryerson University and a Building Science Specialist (BSS) designation.