Blindsided By Mold: A True Story About A Bathroom Renovation Gone Bad – So Very, Very Bad – Part 2

Photo by, on Flickr

In our previous blog, “Madeline” had discovered she had a mold problem – a BIG BAD mold problem.  The source of the moisture leading to this situation seemed to be the master bathroom shower, where a firm hand press against the tile proved that the wall behind it had indeed gone soft.

After getting some idea of the magnitude of the mold growth problem in her home, Madeline’s first scream for help was to the insurance company.

“Does our insurance cover mold damage?” she asked.

“Mold?” replied the adjuster.  “Oh no.  You have no mold coverage.”


Here’s an important factoid for homeowners.  Most homeowners’ policies do not cover mold damage – at least not from a prolonged or overlooked moisture problem.  They typically cover mold damage that results from a single, catastrophic event such as a pipe bursting and the resulting flood, but not a gradual condition.

What Lies Beneath….
Madeline’s next call was to the contractor – a trusted friend of the family – who had renovated her master bathroom 10 years earlier.  We’ll call him “Fred.”

“He didn’t want to believe that the water was coming from the shower.  He really believed there had to be another explanation.  But I made him knock out part of the shower wall so we could see what was happening when the shower was turned on.  That’s when we saw water pouring into the wall.”

It didn’t take Fred long to see what the problem was – two problems to be exact.  And the look on his face told Madeline that he was, himself, sickened by what he saw.

First, upon dismantling the shower, it was discovered that the shower liner (an essential part of a tiled shower installation) was cut short on one side – the side adjacent to the bedroom with mold on the wall.

Shower liner install

A properly installed shower liner in a new construction home.

Shower liners are flexible, waterproof sheet membranes, typically PVC (poly-vinyl chloride) that are installed above the subfloor of a shower.  A layer of cement mortar goes over the liner, followed by the tile – the only part the homeowner will typically ever see.


Liners should be cut to size so that they come up the sidewalls of the shower to a point that is above the shower curb – usually 5 inches.  If this isn’t done, trouble will most certainly follow because (drum roll, please) tiled showers are not are not waterproof, they are water-repellent. Let me say that again.  TILED SHOWERS ARE NOT WATERPROOF!  Thus, the mortar beneath the tile floor where your little tootsies are, is typically wet, even saturated most of the time, assuming the shower is used regularly, which Madeline’s was.

The role of the shower liner is to catch the water transferring through the tile floor and direct it down the shower drainpipe.  If, however, that liner is cut too short, water can and will spill over into the adjacent wall space – which is exactly what Madeline and Fred saw when they turned on the water in the partially dismantled shower.  I believe the word Madeline used, was “waterfall.”

But a short-cropped liner wasn’t the only installation sin here.  The tile had been installed directly onto drywall instead of cement board, which is what should be used behind a tiled shower wall.  Keep in mind that drywall is basically paper.  And what happens to paper when it gets wet?  It soaks the moisture up and breaks down.

In short, there was nothing of any substance in the shower to stop this daily flow of water between the shower and the wall space.  It was, however soaked up by every bit of porous material it encountered, including wall studs, floor joists, wood flooring, etc.  Madeline didn’t realize it, but this area of her home was not only moldy, it had become unstable.

A Sad and Scary Truth
This is a lousy thing to lay on homeowners, most of whom never give much thought to their beautifully tiled showers except …well…to admire how beautiful they are.  But what happened to Madeline happens all the time.  The only thing that is unusual about Madeline’s situation is that it took her nearly 10 years to discover.

However, if you spend as much time as I do eavesdropping on conversations between people in the construction industry, you’d realize how common this problem is.  Plumbers know it, builders know it, mold remediators know it, tile installers know it, and unfortunately many homeowners know about it too, only they usually find out too late.

So, there was Madeline, face-to-face with a contractor, a trusted friend, wondering what would happen next.

To be continued…


11 Responses »

  1. Thank you for publishing this, Trish. I fear I may have mold in my house, and I’m afraid to even think about it. Looking forward to the exciting conclusion, and finding out what it might take to get a clean bill of health for my home.

  2. The vertical liner stops at the curb in the photo leaving a potential water intrusion point where the curb meets the vertical framing. This happens to be where the shower door attaches to the wall and those can leak. Pan installation instructions require a curb dam that is “glued” to the PVC liner at this location or any outside corner to provide a watertight seal.

    • OK, the photo above shows a “correct” installation? So that bench is made from waterproof and mold-proof wood? And I don’t see a slope in the liner.

  3. Good article, but you failed to mention that the liner must be sloped to the drain, per the IRC at a 2% slope. I have found many installations where the liner does not slope to the drain. Proper installation requires the sloped mud base to be installed prior to the liner placement. Another option is a [brand name withheld] which utilizes a pre-formed sloped base.

    • You’re absolutely right with the slope and there are kits available to give you the slope but one we used also failed so we had to redo the mud base and that too was a nightmare. It seemed like this particular shower was fraught with problems as 3 years after my handyman business handled the installation, there was a ceiling leak below.

      My guys couldn’t find the problem so I brought in a licensed plumber who unfortunately found that one of the PVC parts had failed & there was a crack. It happens and it’s tough for everyone, as in this case my warranty is for 1 year including the parts we supply.

  4. Trish,

    Please send your well written article to Mass Media, you all too well said it. The odd thing is it took ten years, I am still laughing. I know it is sad, but I have never read a better account of this “phenomena” . Go figure, please send this to the CSLB (Ca. State Lic. Board). The LARGE majority of Tile Enclosures are Tile on Drywall. I get so many calls, I tell them on the phone,” I can test it, but I want $200″ I also tell them I already told them what I will find for free! but if they are in such denial, I can ad to their problems for $200. The rare times it is not the liner/pan issue, it is the Valve trim that leaked and the result is the same! they need a new enclosure! The water that makes it’s self noticeable outside the wall is already way wet inside and will not dry out in time for Mold avoidance, How can it?. I have see ants and earwigs and mushrooms growing in and thru shower enclosures. Once I saw a morning glory vine coming out of wall seeking light from the crawl space below.
    Greg Chick

  5. Need some advice here, have ruled many floors, but working on my first shower typical 3 wall. The sheet rock guys put in diamond board. Claim it it good stuff, I am not so sure. Question I have is I have preslope patsy 40 mil liner. Problem is the liner is on the outside of the diamond board. Not attached to the studs behind the backer. Appears I am going to have much difficulty getting the tiles to lay flat on the walls. I am using 12×12 for the walls. Can anybody give me an idea of what to do in this scenario? Also learning the so called tile pros at the big box stores give bad advise, they claim I can tile right over the liner with a little extra thunder. Advise please!


  1. Blindsided By Mold: A True Story About A Bathroom Renovation Gone Bad – So Very, Very Bad – Part 3

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