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Top cause of failed shower installations? Installer training

Donato Pompo
Flooring retailers often get blamed when a tile installation goes bad. The installer is typically the last person the homeowner sees and if everything goes well you and the installer are golden. But when the installation goes wrong, everyone comes under scrutiny.  Bad installations ruin customer relations and are enormously expensive to rectify, especially when water damage from a faulty shower install causes massive collateral damage throughout a house.  Properly trained installers can avoid such a catastrophe - that’s what this post is about.

Beauty to Beast - Failed shower installation
We have learned that ceramic and stone installation failures are not usually the result of one deficiency, but rather a combination of compounding deficiencies. One of those deficiencies typically involves installer error. Combined, they can sabotage the most beautiful tile and stone designs and create potentially dangerous conditions that lead to very costly repairs.

Here is an example of compounding deficiencies in the construction of a condominium shower that led to massive damages to the surrounding walls and other rooms in the home. 

Showers are high risk applications

Moisture is one of the most destructive elements to the construction industry causing various types of deterioration and microbial growth that can be a health hazard.  A shower is considered a high risk application because it is exposed to water on a regular basis.  An average size shower used once a day for 12 minutes is subjected to approximately 690 inches of water per year!  Compare this to a typical California roof that only gets about 10 to 20 inches of rain a year or “wet” geographic areas that get 100 or so inches of rain per year.  It’s common sense that a shower should receive at least as much attention as a roof when it’s constructed, but believe it or not, it’s often overlooked.

The case for standards and building codes

Properly installed showers have waterproof membranes between the substrate and floor tile that should continue up the walls for a few inches.  Building codes state that the membrane must be water tight; not punctured with nails or other protrusions, and the membrane should be tested prior to installing tile over it to ensure it doesn’t leak.  Industry standards require that the substrate beneath the membrane slope towards the drain at the rate of ¼” per foot – to ensure water runs toward the drain.

In this condo, the membrane wasn’t welded properly and water was allowed to intrude beneath it. The substrate was not slopped properly; in some areas it was even sloped away from the drain. Plumbing codes and industry standards require a special two part drain to be used in showers with weep holes allowing any water that gets trapped between the tile and the waterproof membrane to escape. Our investigation of the condo shower revealed that the weep holes were plugged with cement, further compounding the other deficiencies.

How the collateral damage occurred. The condo had sound control board throughout.  This type of board is vented and provides a continuous opening that leads all over the rest of the home.  The water from the shower leaked through the defectively seamed waterproof membrane and then traveled away from the shower through the open sound control board collecting in wall cavities and under hardwood flooring of adjacent rooms.  The result was massive water damage and microbial growth in a number of rooms.

To remediate the mold, all of the adjacent flooring and subflooring had to be replaced, along with all of the water damaged walls. (  The ultimate cost to remediate one condo was well over two hundred thousand dollars!  The irony of it all is that, after all of the shower and adjacent flooring was removed, the only dry spot in the whole area was at the drain under the shower because the substrate was improperly sloped away from the drain rather than towards it!

Quality control is key to avoiding installation failures

So what’s the moral of the story?  You have to make sure that installers know and follow industry standard and that they have clear specifications of how to do the work properly.

Installers should be provided specifications from architects or product manufacturers to ensure they are properly constructing installations and using the products correctly.

Installations should not start until the substrate is known to be properly constructed and prepared.

Installers must be properly trained in the trade. Typically, tile and stone installers learn on the job and do not attend formalized schooling.  They will frequently say they’ve been doing installations the same way for 20 or 30 years without any problem.  But that is the problem!  Many installers are not current on today’s industry standards.  Unintentional mistakes can be made that can cost owners thousands of dollars in collateral damages.

Use qualified third-party quality control inspections, especially in high risk applications such as showers or exterior veneers.  This not only keeps installers in check during the installation process, but it also teaches them proper methods.  If you think you can’t afford third party quality control, then homeowners themselves should fill that role by doing the research on industry standards and reading the product data sheets to make sure their installers follow them.  It’s a lot less expensive to pay for quality control at the beginning of a project than to pay for fixing a failure at the end.
We can’t control how well an installer is educated in his or her trade. Most installers learn on the job. There is a need for more readily available, formal training for installers, and we have addressed that with the new UofCTS online TITC Certified Installer training course. The course is called Tile Installer Thin-set Certification (TITC) course for installers who install ceramic tile, glass tile and stone products at

How do you avoid tile shower failures?  By making sure installers are properly trained, by making sure they are TITC Certified by UofCTS.  Showers require a lot of protection from water, and tile and stone are good products to provide that protection, if they are installed correctly.

Visit our website for a free copy of quality control steps for your tile installations.

When there is a problem, regardless of who is at fault, everyone involved will pay one way or the other in money, time or reputation.


Donato Pompo  is founder of two well-known flooring industry companies focused on improving everything about ceramic tile and stone flooring and the businesses that produce and sell them. They are Ceramic Tile and Stone Consultants (CTaSC) and the University of Ceramic Tile and Stone (UofCTS).


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