The Headache of Fixing Our Leaky Shower Pan Ourselves (with Pictures)

For the past year I've known that our shower pan was leaking. We have a one-story house with a crawl space. And had that crawl space not had plastic lining laid, I may've never known—at least, not until the floor caved in, or we tried to sell the house.

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One morning, about a year ago, I was outside, while someone was taking a shower inside. And I heard rain. Coming from the underside of the house. Not good, as it was a sunny day with no clouds in sight.

I kneeled down to peek through one of the foundation vents and saw water just raining down from the area right under the shower. I probably shouldn't say the stream of profanities that exited my mouth, but FUUUUUUUuuuuulminated mercury, I was screwed.

I immediately began researching how much this was going to cost me, gathering information and estimates. The estimates ranged from $1,500 to over $10,000—depending on the soundness of the sub-floor and support structures. I hoped for the lesser amount, but soon found out that was only for replacing and sealing tile (no shower pan replacement). To tear up and replace the mortar shower pan would cost more in line with $5,000. If there was structural damage, that would cost more to repair.

I decided that I could remove tile and tear up the mortar shower pan, and if there was no damage, I'd just fix it all myself. I told myself that this would be hard, but doable over a long weekend.

It was definitely hard. The YouTube videos showing skinny guys with sledge hammers breaking up the mortar were misleading. Or, I should say, my perception of *my* sledge hammering abilities were grossly overestimated. After two hours and barely a dent, I hopped in the car, drove to the box store and  bought myself a hammer drill, the kind that actually hammers and doesn't just oscillate (there's a difference)—and it made all the difference in the world. After 5 minutes, my floor looked like this:

It took another 45 minutes to break up the mortar bed (and probably 20 minutes to clear it all out).

I got the mortar bed up and revealed the shower membrane. (I'm not sure what the purpose of that rectangular bead of caulking was.)

Immediately, I noticed multiple issues. First, the entire left side, especially the lower left corner, had standing water. Second, there was a huge rip in the membrane next to the wall, above the drain. Third, along the curb, there were screws holding the membrane on, both inside and along the top of the curb.

I removed the first row of tiles by cutting through the grout with an oscillating tool, then prying them out carefully with a pry bar. I cut the cement backer board about an inch down from the grout line, so I'd have room for mud and tape when I put up the new backer board.

I then started pulling up the membrane.

My heart sank. My worst fears were going to be mold and/or rot. And here we have no shortage of rot.

With the membrane up, I could see more of the damage. Next was to get the curb up and take a look at the sub floor. While prying the curb up, however, I went through the floor and discovered that the previous owner had placed plywood over the original lathe sub floor, and both were completely rotted through. It was so rotten and spongey that I could poke my finger right through it in spots.

So, I began pulling the flooring up. The entire left side of the shower floor came up a little too easily. I used my circular saw to cut through the depth of the sub floor and pull it up, leaving about an inch of space around the edges for the original sub floor to continue to rest on the joists. I also discovered that the joists were spaced unevenly.

The joists should have been 16 inches on center. One was just that, the other was 13 inches on center. Come to find out that one of the joists had been sistered at some point.

Both the center and the lower left joists had considerable rot. As did the sill support.

I finished tearing out the sub floor, and built 2x6 frames to fit between the joists. I also toe-nailed in cross pieces under the shower head wall to further support the sub floor that had been cut there.

Because there wasn't much space between joists, I had to screw the boxes to the joists (sometimes by hand—with a tiny ratchet).

Then I scraped all of the rotten wood out, let it dry as much as I could, and filled the gaps with wood rot floor filler.

This was day 4 for the project. When I'd planned out the project, this was the day that I'd be re-laying the tile in our newly fixed shower.

Instead, I measured and cut the first sub floor and coated it with water proofing membrane.

I got it dry-fitted into place and realized the extent of the floor slope. From the far right corner to the lower left corner of the shower, the floor dropped 1 inch. The previous owner tried to make up for this in the mortar bed, but that didn't help when the shower membrane failed.

So, I shimmed and built up the joists, gluing, caulking, and screwing shims until the shower floor was level again. I then started building the shower floor and curb in preparation for the shower pan.

Every step of the way, with each layer, I painted more water proofing membrane, and caulked.

I watched several YouTube videos on how to fold and screw the membrane into place. The best suggestion I came across was to let the membrane sit in the sun to warm up so it would fold more easily. Very helpful.

The previous membrane installation didn't have the membrane wrapped in the corner (below the bench seat). Whomever installed it, just cut it, leaving a gap. Amazingly, there was no rot, but there was a damp smell in the closet on the other side of that wall. So this time around, I just made sure the membrane was wrapped and secured in that corner.

I also didn't trust my skills to create a correctly sloped mortar bed, so I got the Quick Pitch and Kwik Kirb products.

Kwik Kirb allows you to create a mud curb without using cement board or screws—eliminating the possibility of holes in the curb membrane.

We mixed a very dry mortar, then packed it in and smoothed the surface. It dried overnight and we were able to start tiling the next morning (at this point, day 7).

I did have to re-do the curb because I didn't understand that the mortar for the curb needed to be wetter than the mortar for the shower pan. So I carefully chipped out the dried mortar that made up the curb, cleaned it up, then remixed and repacked the Kwik Kirb.

After the floor was set and grouted (days 8 & 9), I focused on putting the cement backer board and curb tile back up. Making sure to tape, mud, sand, and paint another coating of waterproofing membrane over the surface. The cement backer board sits about a half inch above the tiled shower floor. When I reset the tiles, they'll float about a quarter inch above the floor.

Putting the wall tiles back up (day 11):

No one had the exact matching tiles. The previous home owner kept his receipts and kept a record of the tile brand, but when I went to Lowe's to get that same brand, the tiles were no longer an exact match. Not only was the color different, but the tiles weren't as thick. I was able to grind the old mortar off some of the original tiles and re-use them, but had to play around with the thinset a bit to get the tiles to sit flush to one another.

By this point, we are approaching the end of week 2 of our 4-day project.

After the tile went up and was grouted, I then went over all surfaces with a tile and grout sealer. The wall tiles are porcelain, so don't really need to be sealed, but the floor is stone. In total, I did 4 coats. Admittedly, the last two were overkill, but I never want to have to do this again.

Then we worked on getting the track for the glass partition installed and caulked. After that, the glass went up and got a line of caulk wherever it met a perpendicular surface.

This is how our shower stayed for most of the Summer (with a shower curtain hanging inside the glass). Because the original shower door was cut for a sloping floor, it no longer fit now that the floor was level. Instead, we had to hire someone to cut and install a custom door (which was not cheap). Getting people to come out and give us estimates also proved rather difficult. We had two no-shows and one company booked so far in advance that they couldn't fit us in for an estimate for another 6 weeks. So that was a pain.

In total, the shower pan replacement cost us $1,700 in materials and took us about 2 1/2 weeks to do. The custom shower door cost us $759, and after all of that, I bought us a new (fancy) rain shower shower head (which was $239 with tax). In total, the project cost us about $2,700 to fix and upgrade a bit. $1,300 below the lowest shower pan estimate (which didn't include a new tool for me—hello hammer drill, a new shower door, upgraded stone tile, or new shower head).

It may not be the most perfect job, but it will take an act of God for that thing to ever leak again. (knock on wood.)

If I'd had a spare $5,000-$10,000 laying around, I would certainly have hired someone to fix the issue. Although, now that it's done, I have to say that it's nice to know that I was capable enough to fix it myself.