cme4dk said:
Questions:
1. Should we mix Xypex Concentrate in the concrete (we happened to come across some for free)
2. What is the best fluid applied waterproofing that tile can be set directly to or are there sheet products that tile can be set directly to?
3. Since we aren't putting a sheet liner below the mortar bed, is there any benefit to using a drain that has weep holes?
4. Do we need a vapor barrier behind the cement board if we use fluid applied waterproofing on the verticals? The bathroom doesn't have a fan so any vapor will go through the ceiling anyways, correct?
5. What are we missing?
Can I start with #5? You're missing a lot. (No offense intended)
Fist off, you're not using concrete... You're using drypack, aka mud, it's just sand and portland cement, roughly 5:1 ratio... It's mixed with very little water, you're not looking to make a soupy mix. People may say they've "poured" the pan, but it's really "placed". When mixed, you can grab a handful and squeeze it into a lump. If it wont hold together, add a little water.
You can grab bags of Sand Mix from Homer's and add some mason sand to lean it out. I usually go two 80lb sand mix and one 50lb sack of Masons sand. Dont put any type of admix in to the drypack, it makes it harder to work with when forming your slope, and really serves no purpose...
Next, best fluid (liquid) applied membrane is HydroBan, made by Laticrete. You cant just put any drain in and liquid membrane up to it though. There are ways to use liquids on a clamp drain with weep holes, but for DIY, you'd be better off buying the manufacturers flange type drain..
No vapor barrier behind cement board if you're adding a topical membrane, be it sheet or liquid.
Now, what are you missing? I'll give you the quick tutorial for a surface applied membrane shower build:
1. Insulate where necessary
2. Build your curb out of 2x4, or whatever size you'd like. No Pressure treated.
3. Apply cement board to the walls and curb, tape and thinset the seams and corners. (Not necessary with fabric membranes, but definitely with liquid)
4. Tar paper and expanded metal lath stapled to subfloor
5. Test fit the drain leaving at least 1 1/4" under for mud, and using levels or laser calculate 1/4" per foot slope to the farthest point from the drain. Mark that height around entire shower to form your level perimeter.
6. There's two ways to set the drain with the mud, either place a ring of mud under the drain area, apply glue to the drain flange and install onto rough-in while smooshing into the mud... The easier method for DIY might be to glue your drain onto the trap first ensuring proper height and level, and then pack mud underneath it. If you go with method one, I also add some thinset to the back of the drain before the smoosh to help it adhere better. Sometimes a loose trap underneath can allow the drain to disconnect from the mud floor when there's a lot of early traffic on it. Keep adding mud to your shower floor packing it in with an old hard grout float or wood block as you go. Take your time to get an even slope from drain to perimeter all around. Any low spots will hold water after you tile and just pee you off.
7. The next day you can apply a sheet membrane like Kerdi, but if you're using liquid, you have to wait 3 days for the mud to dry out. Make sure the liquids are applied thick enough, and if you grab one that requires mesh in the corners, make sure you use it.
8. Start tiling. I put a ledger on the wall one course up and tile the walls. This way I dont have to wait for a floor to set. I do the floor next, and then fill in the bottom course of wall tile. You can go in whatever order you feel like.
I usually do a bit of a hybrid method. I mostly use Kerdi with the Kerdi drain, but always use liquids in recessed shampoo niches because the fabric membranes require overlaps that just build up too much inside tiny niche spaces. Liquids are faster and easier in that case. Occasionally I've used Kerdi drains and Kerdi'd the floor while doing the walls with HydroBan. I dont believe either company will warranty that install, but I'm comfortable with it (as are many other installers).
