Here are a couple of photos showing the growth of mold in behind the tile and between the vapour barrier and gypsum based drywall.

The tile was covered with cheap vinyl tub enclosures (not shown here) in an attempt to hide the loose tile and discoloured grout.



The next photo shows the failed wallboard and tile installation. The black areas are the mold.
The material in my hands is soaking wet pieces of greenboard which I pulled off the wall with my fingers.

The curb of this shower is failing after only a few months.
The cracking is caused from movement within the structure of the curb.


The mastic which is barely holding the tiles in place is still wet. Water is somehow getting into the cement backerboard either through the liner or by severe wicking from inside the shower pan.

From the pictures, it looks like the tile setter did a decent job of the actual tile installation....too bad his procedures were all wrong. Mastic in a wet area :rolleyes: a picture is worth a thousand words.

Harry, how did the water get past the tub surround and the tile...or was there another reason for the moisture behind the wall?

That is nasty stuff.
Harry, can you tell us exactly how long ago that shower was built? I like to print pictures like this to put in my "CRAP ALBUM" to show people how to do a shower the wrong way.
By the way, I suppose I should ask if its ok to copy pictures and stuff.

The shower was installed only a few months ago. I'm still not sure the "real" cause of so much moisture getting into the structure, but suspect that the liner has failed. Unfortunately the pan was never repaired properly. The tiles were re-attached with mortar and although it's better than mastic .... the grout will eventually crak again.

Randy ... use whatever photos you want.

Just became a member due to research on mold and poor quality instalations. Your pictures of the wet green board behind the tile is what I am experiencing on a project.
We are currently seeing a typical instalation method that uses visqueen over the studs then greenboard covering the visqueen then a mastic used to secure the ceramic tile with no sand grout. We are getting moisture absorbtion in the green board and mold between the green board and visqueen, and the green board failing due to moisture.
Can you give some advise on what we are doing wrong. By the way this is on insulated exterior walls

Hi Jim
Any ceramic tile installation directly over greenboard will fail IF moisture is involved. It's absolute garbage in any area where water can be a factor.
I'd recommend using cement board and a thinset mortar to bond the tiles to the cement board.

There are also ways to waterproof the backerboard before setting tile. Even regular drywall will work if the proper waterproofing system is applied.
Tell us more about your project and maybe we can come up with some good ideas for you.

Hello Harry: Thanks for your time, I see shower stalls built this way, studs, visqueen,greeboard,a tile adhesive, tile with non sand grout. The only time we are seeing any problems is on a exterior wall with insulation between studs, osb or foam board exterior wrapped with a tyvex type product then vinly siding. The tile people tell me they don't know what is causing the moisture, I feel its coming through the grout, then cracking the grout after the green board swells a little. This is not happening on interior walls just on the cold walls of the exterior.

I want to add something I learned from an insurance person who educated me on the use of waterproof stucco. She paid claims on houses where the house was so tight with visqueen, insulation, osb and tyvek wrap, the moisture was kept in place and caused severe damage inside. I have seen so many problems from using greenboard with mastic but have also seen no problems there. If a tiny crack appears in the grout joint or if moisture starts getting inside then the trouble begins

Every single time I have to pull out shower walls, it's because the greenboard has absorbed a ton of water. I always replace this with cement board instead. And any new installations, I insist on it. That, proper grouting techniques, and a good silicone job (neat, yet complete) will ensure a long-lasting, moisture-freeshower for years to come.