Hardie Backer

[Ando]

Hello all, new to the forum!
I am currently remodeling my master, concrete shower.
The pan liner is down and I’ve started the backer but from what I’ve been reading here, I don’t want to pour my post liner on the hardiest backer, .
My question and I’ve looked but don’t see my answer is can I redgard the hardie On the back up 6-8” and the whole front will be redgarded too, and set it in the floor mud?.. thank you

[cx]

Welcome, Ando.

Not sure what you mean by a "concrete shower." Perhaps you could give us a little clarity on that?

Presuming you mean to use Hardiebacker for your walls, the manufacturer says you may not bury the bottom edge in the final mortar bed of a traditional shower receptor. If you want to do that, and I would, I'd suggest you use a different kind of CBU for your walls. A real CBU (ASTM C1325) rather than a Fiber/Cement board (ASTM C1288) such as Hardiebacker. Several different brands available out there.

Or you can try your RedGard method and see how that works out for you.

My opinion; worth price charged.

[Ando]

Concrete as in no sub floor, concrete slab foundation...
I’ve got a lot of my material already and hate to return it.

[Tool Guy - Kg]

I say this out of wanting you to have a good, long-lasting install:

Your reason for not wanting to return an inappropriate material in favor of an appropriate material is detracting from your quality level.

[Kman]

I think it would take more time and effort to do what you propose than to return the board and get one of the true cement boards. Keep in mind that if you want to cover every possible point of contact between moisture and Hardibacker, you're going to have to paint every edge, including the ones you cut to fit your shower. Seems like a lot of work.

Durock, Wonderboard, and Permabase are the more available cement boards out there.

[Ando]

It’s about 4’x4’,



.

What would be the best way? Pan liner material lath and mortar? Hardiebacker taped and redgarded? Thanks for your input.
Ando

[cx]

Ando, it'll help if you'll keep all your project questions on one thread so folks can see what you're working on and what's been previously asked and answered. A moderator can give it a more generic title any time you'd like to suggest one.

I'm afraid I can't tell much about your installation from your photos. Is that fixed glass unit just sitting within the framing of that wall?

Is this an exterior installation?

[Ando]

Ok, thought this would be a new question for a new thread but now I get it.. yes, it’s a fixed interior window, I want to make a shelf where the sill is with marble or tile. There’s about 3 1/2” in between wall and window, frame is aluminum. I want to make sure it’s sealed before I start tiling.

[Carbidetooth]

You'll have to adapt to your situation, but this gives general idea. The sill should be an applied piece and not part of waterproofing strategy. Slope is exaggerated in this graphic but should be same as curb or floor...1/4" per foot.

[Ando]

Yes there will be a slight pitch for run off, what would the “cant strip” be made out of?
Also I’m wondering should I screw the hardiebacker through the aluminum frame or maybe be safer glueing? Yes I will seal all edges with lexcel or silicone.

[Carbidetooth]

I'd make the cant strip of wood.

I'm having a hard time imagining how you'd screw Hardie to window frame, but would recommend against it. If you're talking about the rough house frame, you could do that.

The biggest problem I see is tying the existing RedGard to whatever you line the jambs with. This has to be bulletproof. I like windows in showers, but it's done poorly in many, if not most, cases.

[Ando]

Of course I could drill a pilot hole and Screw hardie on, , there’s screws holding the window in place..
I’m still open to putting some lath in there and putting a 1” slab of mortar but I’d love to hear from some of the “mudmen” on this site who are real pros!
Anyone?

[Ando]

I’ve taken a couple more pics,





So now what I’ve been thinking is putting down hardie and wrapping in 5” kerdi membrane.. is this I good idea?

[cx]

First photo makes a world of difference, Ando. I now see what you were talking about when you spoke of drilling through your "window frame" to attach your CBU. I'd have no problem at all with that approach, so long as you are able to ensure that the CBU on the bottom is sloped to drain.

Adding a waterproof membrane over that would would seem to solve your problem. I'd still want the membrane to lap up onto the vertical portion of the window frame and be attached there with a good adhesive sealant, such as Kerdi Fix. That portion would be hidden by the tile when installed.

My opinion; worth price charged

[Ando]

Quick question, Taping and thinset, Should I put tape down and press thinset in or thinset and tape on top?