Shower Waterproofing

I got this idea from @Isaac Ostrom and one of his videos. When I did my first shower pan mud bed, I used Coach's ledger method, but ended up messing it up by not having enough mud and had to do a bit more work to fix it (documented here: https://www.tilecoach.com/forum/shower-waterproofing/shower-pan-mud-bed-questions). I decided to try this: exterior PVC trim on the outer edge to act as ledgers/screed guides.

Here we are, with everything in place:

The PVC board becomes part of the shower pan and is compatible with my liquid membrane, AquaDefense.

Here we are with the mud bed installed:

TL;DR:

This was a lot easier than the other method, given that this was only my third mud bed. Results were pretty good.

Details:

1. With my last two mud beds, I think I made my mud just a little wetter than it should have been. I was making it easier to mix, but sacrificing work-ability. I was careful with the water and mixed well.

2. Speaking of mixing well, this was all done by hand. I tried the trash bag method of mixing for my last mud bed, but I prefer seeing what I'm mixing. I used a mortar hoe and large mortar pan, which worked great. I wish I had not sold my cement mixer years ago, as it would have been great.

3. I used Mapei's 4-1 mud bed mix, rather than mixing my own, to keep it simpler for me. I was already used to it with the other two beds, so it was smart to stick with what I was familiar with. If I were a pro, would probably mix my own.

4. I ended up having half dozen screeds. I used scraps of PVC for two of my screeds, but they flexed a lot and were not a good choice. The homemade aluminum screeds I used last time (90° angle) worked the best, followed my my wood screeds.

5. I used my metal cement trowel almost exclusively, rather than the wood float. Worked well for me.

6. I beveled the PVC when I cut it with my table saw, just about 1.5°, angled towards the drain, of course. I didn't want to have a little ledge around the edge of the shower. This was a great idea. Slope, slope, slope.

7. This took me just under two hours, or two hours if you include prep and cleanup.

8. This used about 3.5 bags of mix, which was less than I had estimated. My daughter ran water for me, as I mixed this in the bathroom (second floor) with my box fan air scrubber keeping the dust down.

9. I stored the mix inside, as our nights are getting cold and Mapei recommends 'heated room' for most of their products. I wanted the best outcome possible

10. Mud bed is about 1 1/8" deep at the edge of the drain flange. I really packed the mud under the drain very well.

Overall, it came out nicely. The right side looks a little sloppy, so I might need to clean that up a little after curing. The big thing is that I wasn't as stressed about everything looking perfect. It has a good slope (3/8" for pebble). I have a dehumidifier running in the room to help with drying.

So there you have it. I will apply waterproof mid-week and keep on moving. Should be tiling by next weekend.