Ralphs Bathroom total rebuild

[Gnfanatic]

Hey guys, My entire bathroom is down to the studs and subfloor. Before I even go any further with the progress I need to ask you 2 questions. I did search the forum and could not find a solid.

1-) My cast iron bathtub gets installed FIRST then the mudfloor in the bathroom??? The tub came with a finished wall.

2-) once the tub is installed I sheetrock the wall, correct?? or does the sheetrock go behind the tub at all 3 sides??

thanks!!!!

[cx]

Ralph, both those questions depend upon other considerations and there are too many available guesses.

1. Are you planning to build a tub/shower, or just have a tub?

2. Is this tub free-standing, or made to be enclosed?

3. Do you want the tub to be full height above the planned mud floor?

4. What is the purpose of the mud floor?

5. Etc.

Without knowing the plan, it's tough to be part of it, eh?

[Gnfanatic]

Sorry about that!

1-) tub/shower combo

2-) made to be enclosed except for the one side thats finished.

3-)not sure??

4-) putting down marble mosaic tile, not to mention I have radiant heat.

[cx]

Mmmm, OK, I was givin' hints hopin' we weren't gonna need to do this tooth by tooth on accounta you got enough threads out there I figgered you must at least be aware by now that you've gotta select your waterproofing method before we can discuss the shower walls and you gotta evaluate your floor structure before we can discuss installing tile.

Have you done either of those? It'll help us get started.

[Gnfanatic]

Hey, floor is solid and ready to go (2x8 , 16 oc, 3/4 sub, 8 ft span) I am going to be doing a 4:1 mud job (1.5 inch thick) like the rest of the house has.

The walls: going to use 4mil poly, 1/2 sheetrock and kerdi around tub/shower area. obv I will be using a non-modified to install the kerdi. I do not have any idea on tile's for the wall yet, might be marble to match the floor, not sure. might be to exp.

[cx]

OK, you understand we're talking about the unsupported span of the joists, not about size of the floor to be tiled or any other such measurement, yes?

And you still technically need the double layer of subflooring, properly installed, under your mud for your natural stone installation. (see post #9) You'll put 2x2" wire mesh in the center of your mud, yes?

That mud ratio is a little rich for my taste. It's the industry standard for shower floors (dunno why), but for regular deck mud you can go a little leaner (5:1 my choice) and it'll work a bit easier.

You must not use a vapor retarder behind the sheetrock if you intend to use Kerdi to waterproof your shower. Bozo no-no, that.

[Gnfanatic]

I guess you mean if I use the 4mil poly AND the Kerdi and I will trap moisture and cause rot? interesting, did not know! thanks

The span is 8 ft
the Marble mosaic is less then 1/2 thick

I put down 30 lb felt on sub, then the wire mesh and then the mud.

I never heard of putting 2x2 mesh in between the mud for a floor?? I thought the mesh was used for the mud to stick better.

[Gnfanatic]

Here is the tile

[cx]

Originally Posted by CX

And you still technically need the double layer of subflooring, properly installed, under your mud for your natural stone installation.

Lemme correct that. I just consulted my brand new, never been opened to that page, TCNA Handbook, which for the very first time now contains guidelines for natural stone installations, and it says you can use an un-bonded, reinforced mud bed over single-layer plywood subflooring over joists on 16" centers. Still need the double layer under CBU, though.

New specs also appear to permit such installation over joist systems with a deflection of L/360.

Gonna take a while for some of us to adjust to this new publication, I'm thinkin', but we'll do the best we can.

I trust by "then the wire mesh and then the mud" you mean you used a metal lath attached to the subflooring, yes?

If so, that doesn't qualify as an un-bonded, reinforced, mud bed for purpose of this installation. You gotta have the wire mesh in the center of the mud bed for this method (F141-11 Stone).

But since you've already done what you've done, I suspect that's what you're fixin' to use, eh?

My opinion; worth price charged.

[Gnfanatic]

cx, nothing has been done yet because I wasn't sure how to layout the radiant pex due to me changing my design all the time so right now i have a naked floor as well, just the subfloor

[cx]

Good, I retract my retraction of my initial statement of the requirement for a double layer of plywood subflooring for any natural stone installation.

The new TCNA Handbook, just published, that contains the method using a single layer of 5/8" plywood also appears to allow L/360 joist deflection rather than the far more rigid L/720 customarily required by the MIA.

Not quite sure what we got going on here, but I'm pretty sure I wanna continue recommending the old standards until we can fine out just what's changed.

We've gotten away with a lot using a reinforced mud bed over the years, but I'm not sure we wanna be recommending we go that far. We'll see.

'Till then, I reckon you can do whatever you wanna do. Me? I'd want the two layers of subfloor, properly installed, for your stone tiles. Over that I'd be content with your metal lath and minimum 3/4" mud bed, but I'm not sure what the industry thinks of that as it's not a published method for stone in the new Handbook.

My opinion; worth price charged.

[Gnfanatic]

Damn, these little stone tiles weigh that much more then porcelain??? I thought the thick marble or real slate was the heavy stuff. I need this bathroom to match up with the rest of the house floor. which is a 1.5 inch mud bed. if I install 3/4 ply now I only have 3/4 inch mud , that sure sounds thin as hell, no?? I know you are extremely knowledgeable and I appreciate your help. just curious ! thanks!!!

[WendyHMN]

It's not about weight. It's because stone is natural. It's weak in spots and more prone to cracking than porcelain. If the floor wiggles at all you are likely to get bad results with natural stone. Porcelain isn't entirely forgiving, but generally you'll get grout cracking instead of tile. Stone is pretty, but it exacts a price in the form of a rougher install and higher maintenance.

[cx]

Ralph, you don't need another 3/4" layer of plywood, half-inch will do if properly installed. You get you a really good subfloor and an inch of mud over metal lath should take care of your tiles. The unbonded 1/1/4" minimum with reinforcement would be better, of course, if you can find room.

My opinion; worth price charged.

[Gnfanatic]

Thanks cx, please keep in mind those I have 1/2 inch pex with clamps under that 1 inch mud so the pex will have will 1/2 inch mud over it and the clamps will have 1/4