See how I repaired this moldy, water damaged shower! By: Harry Dunbar
View from inside the shower.
Look at what the moisture has done to the gypsum based backerboard. There shouldn't even be backerboard on a shower curb! These tiles can easily be picked off with your fingers.
This is the wall / ceiling area. The discolouring indicates water damage and possible mold.
The floor / wall section inside the shower.
I don't have to rip it apart to know what the problem is. It's obvious and unfortunately it's common.
1. The liner was laid flat and without a pre-sloped mortar bed.
2. The backerboard is a gypsum product which hasn't been waterproofed.
3. The backerboard is setting on the liner material (in a puddle of water) therefore causing moisture to "wick" up into the walls.
Damage has occurred outside the shower as well. Once moisture starts wicking into dry gypsum it spreads. Moisture has discoloured the marble.
The jackass who did this job needs his ass kicked!
Here's what I'm going to do to fix this mess.
First I'll rip out all the backerboard and tile, I demolish the shower pan along with the slab. I remove the entire back wall so that I can rebuild it about 10 or 12 inches deeper, re-locate the plumbing hardware and re-set the drain location.
KILL THE MOLD!
Then we build a REAL shower!
Because the home owner had valid concerns, the shower hasn't been used for over a year. The 2"x4"'s constructing the curb and almost 2 feet up each side are rotted.
It's no surprise to see the liner laying flat on the floor. This mortar bed would have been constantly soaked, which would account for the water damage in the curb and up all the sides.
I've knocked out the back wall into the hall closet and bathroom in order to make the shower larger.
Before I install the backerboard, I'll first need to straighten out one of the studs which would otherwise cause a bow in the wall.
I've cut the stud almost all the way through.
I think you get the picture.
Then I sister another 2"x4" stud along side.
The Kerdi drain is installed before I build the mortar bed.
The deck mud is forced under the flange of the drain giving the mortar over 1 inch of thickness at it's thinnest point around the perimeter of the drain.
The deck mud can also be used to level the drain.
The Kerdi membrane is used to waterproof the shower pan and walls all the way to the ceiling.