Durock Installation Question

[Thomas K]

These photos show area tub will sit in. I put vent for tub where it is because I put blocking under where tub feet will be, and it will be tight there for installation of tub trap. I think I might have gotten pipe too close to wires there (image 1970-71), and may have to redo it. Other photos show vent routing and pocket door near tub. I think tiling up to door trim will be ticket, and make new wall (have yet to frame) same width as tile at front of shower. I was wrong about the tile size; I said 6" x 12", but they are 12" x 24".

Other photos show Pex work I have done. Referring back to older posts, I could not get 4" vent pipe to give me the proper slope on drain pipe (if you're listening in, Wayne ) so I had to use the 3" option you suggested. Even that way, 3" combo fitting was almost touching joist, but I got a good slope. Replumbed sink back to 3 x 2 fitting, and used 3" combination fitting from vent to drain. 3" drain pipe to toilet in smaller bathroom, but everything beyond vent pipe combo valve is still 4".

 

[Thomas K]

Wedi board kit is around $260 for five panels, and 1/4" thick. Not sure if that would be okay for the heavy tiles we bought. I looked up Kerdi board and it's around $40 a sheet and unavailable around here. Not knocking the stuff, but I've had experience with Durock 1/2" and using RedGard sealer (I built a natural stone shower from scratch). I measured this afternoon, and tile flange of this particular Kohler cast iron tub is around 1/4" in height, so board will have to be really close to tub to overlap.

 

[Sponsor]

 

[Jadnashua]

At 1/4", get the board close to the top of the flange, but not touching, and use some seam mesh tape and RedGard it. Use some pure silicone caulk between the tub and tile. Yes, it's harder to install than an acrylic, but will last much longer. Foam backer rod will also extend the life and bond by making it more into an hourglass shape versus a block, putting less stress on the bond , making it easier to stretch versus a block and tearing away from one surface or the other.

 

[Jadziedzic]

I'd go with 1/2" Wedi or Schluter foam board over cement board, especially because of the fact you can rabbet the bottom edge of the board so it fits over the top of the tub nailing (or screwing) flange. It's also a heck of a lot easier to cut in a niche when using the foam boards. (And yes, I also built a custom shower using cement board, and were I to build another I'd go with the foam board.)

Having "shingled" surfaces to shed water instead of depending on seam tape and sealant strikes me as a much more reliable way to ensure no long-term issues arise.

 

[Thomas K]

This tub doesn't have a nailing or screwing flange. Just a slight dimple for the flanges, about a quarter inch tall.

 

[Jadnashua]

On bare stud walls, Schluter calls for 1/2”panels. Personally, I’d be Leary about using 1/4” Wedi panels even if they allow it. Applied over another panel, okay.
The size of the tile isn’t an issue. The thickness might be, but it’s all in shear on a wall.