Heated Floor Shower and Bathroom Project

[Engineerly]

Editor's note: The drawings on this first posting are obsolete, but I'm leaving it here for history. The trench drain idea was abandoned in favor of a "new-conventional" schluter drain over deckmud. Look farther down the thread for photos as the project develops over the next couple of months.
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This is my second major tile project. There were no major blunders with the tiled kitchen counter with flush mount sink, so my confidence is boosted enough that we've taken on the masterbath. We have already gutted it and are well into the detailed planning phase which I may need some advice on. Thanks in advance.

Here is a floor plan sketch (dimensions are approximate):


Here are the main and possibly unusual features.
- curbless shower with bench opposite the shower head.
- trench drain opposite the opening
- shower curtain to prevent splashing onto main floor area
- electric heated floor throughout
- all tile is lightly texture porcelain of same color (whitish with darker grout)
- 4" square tile on shower floor
- 12" square tile in main floor area
- 6" and 4" tile on shower walls and on the left wall all the way up to the ceiling.
- a tiled header to hide the curtain rod.
- recessed light in ceiling of shower

I'm planning on engineering the trench drain using off the shelf materials knowing full well that it must be permanently waterproof. The subfloor is 5/8" OSB and the floor outside the shower has 1/2" plywood on top of that. The floor joists are 16" apart and run parallel to my planned drain.

Here is a picture looking into the shower:


And here is a picture looking from the shower into the bedroom:


Here is a floor-level sketch of my current plans:


I expect to install the shower floor (after I figure out the drain) in this order:
- sloping mortar bed (1/2" drop over 48")
- NuHeat or Suntouch heating mats or wire (which ever is best)
- Thinset (modified?)
- Kerdi waterproof barrier
- Thinset
- Tile
- Grout

Outside the shower would be the same except for the sloping mortar bed. I want to make the finished floor continuous from the hardwood in the bedroom to the down slope which starts just outside the curtain. Why I only have 1/8" per foot slope is that I don't want to raise the main bathroom floor. So the sketch shows the mortar bed only 1/2" at the thick side and feathering to nothing towards the drain.

Another thing I need to make sure of is: is it really ok to put the Kerdi membrane on top of the heating mat and thinset and how can that be made flat enough in prepration for the tile which goes on top after that with another layer of mortar. The Schluter video shows the guy pressing the excess mortar and air bubbles out from under the membrane, but if the wires are under it that will be very difficult.

So what other problems/concerns do you all see with any of this? Any and all advice is welcome.

Thanks again,
Ron

[Engineerly]

I'm bumping this because it may have been an overwhelmingly long first posting and I scared you all away. Or maybe I'm asking stupid questions which have already been answered a hundred times before. If so please be kind and point me to a thread or what key words to search for.

Most of the original posting is just info, so I'll extract the 3 main issues here for simplicity:
1. Is 1/8" per foot shower floor slope totally inadequate?
2. Has anyone here successfully made their own trench drain and if so how?
3. Is my 5/8" OSB subfloor too weak? Any suggestions for reinforcing it?

Thanks, Ron

[Ken]

Too start you off, have you ran your floor structure through the famous "Delfecto"

That'll be a good start to see if your floor joists are up to snuff.

Personally I WOULD GET RID of the OSB and replace it with exterior grade plywood. IF your OSB somehow gets wet, it will expand.. gets wet again, expands.. you get the picture.. it will always swell, and never contract back.

I've never made my own drain.. however I hope you have a welder handy

I would have to say an 1/8" per foot slope isn't quite enough.. i'd shoot for 1/4" if i was you.

[Engineerly]

Deflecto says 655 which is on the high side. We have pretty much decided on 4" porcelain on the shower floor. I will be reinforcing the joists and subfloor from underneath since I will replacing the OSB with a thinner exterior grade plywood in order to obtain the required slope.

However this still means that at the edge of the trench, back on top of the floor, the deck mud will have to be feathered to 1/4 inch or so. Is that possible or even wise? I'm planning on adding a new joist directly under that feathered edge to support it and the top flange of my (copper sheet?) trench drain.

Also, notice that I'm planning on putting heating a mat down on the main floor and shower floor. I'd like to dam and pour SLC on the main floor covering the mat, but what would you suggest to embed the mat while creating the slope for the shower without any discontinuities from the main floor area? Since it is a nice straight slope, I feel comfortable screeding deck mud there after the main floor is poured, but I'm NOT comfortable trying to imbed the relatively delicate mat into the dryish mud. Is this project getting interesting yet?

I WILL be posting more pictures as this project moves along.

Thanks for your feedback,
Ron

[Engineerly]

It's ok if this becomes a blog but feel free to jump in if you have time to prevent me from doing anything real goofy.

So due to the expense/unavailability and unknowns of trench drain systems in homes and the need to push this project forward, we decided to go with the tried and proven Kerdi-Drain over mortar bed.

Call me a "rebel without a clue" because I always try to do things a bit different. What are the disadvantages if any of putting the drain closer to one corner instead of centering it in the floor space. The advantage would be to not always be stepping on the shower drain. Obviously that would make a steeper slope between it and the closest wall, but is that a problem? The shower floor dimensions are 42" x 48".

And I'm having a hard time finding an example of the technique for putting the electric heating mat on the shower floor. This would go on after the mud bed sets then embedded (mesh side up) in a layer of the unmodified thinset with the Kerdi membrane laid directly on that right? Has anyone actually done this? The floor tiles will be 4" square porcelain by the way.

Oh... and for fun, here is a picture of our color scheme:

That is the hardwood floor from the bedroom (and possibly the cabinets in the bathroom), one of the 4" tiles, the light blue wall color, the grey toilet and pedestal sink and the brushed nickel for the fixtures.

[prescottrecorder]

Well, I don't know if this will work for your unusual situation, but I heated my shower floor with a low voltage (24V) step warmfloor mat. I believe that other styles of heating mat can also be configured for low voltage operation.

I put the mat under everything. In other words, right on the plywood subfloor, then covered with a layer of plastic, then mud bed, then Kerdi. It works great.

[bbcamp]

Deck mud needs to be 3/4" minimum and reinforced with metal lath stapled to the subfloor. I think I'd rather embed the heating mat in a mud bed over the entire area than have that plywood to mud joint at the edge of the slope.

[Engineerly]

Thanks for the comments. Things are really moving along already, at least in the sense of making commitments and buying materials. I've done enough research to feel confident enough o start putting it all together now, but I'm sure I'll have a few questions and will keep you posted on progress.

I'd kinda like to start this thread over since I have abandoned the trench drain idea and have learned so much since those initial diagrams (which are now misleading). I could give it a shocking title like "120V Shower" (moderator, is it ok if I do that?).

So here are the new main ideas (not in precise order of execution) :

1. Lowering the shower floor enough to give me a 1" base under the kerdi drain flange and a 1/4" per foot slope.
2. Woodframe bench in shower (under Kerdi).
3. Curbless entry with slope starting just outside the curtain.
4. Installing Kerdi drain with deckmud base (purchased Kerdi drain, membrane, band and corners from Tile-Experts yesterday).
5. Electric floorheat in shower and bathroom floor (purchased 34 ft length and fancy thermostat from WarmlyYours ($50 off)).
6. Using 12, 6 and 4" Venetian Railto White porcelain tile from Lowes (3 x 12 bullnose will be used for baseboard on non-tiled walls). This will have "dirt colored" grout.

Although strictly not necessary, my Durock is going 7 feet high on the shower walls because I just like things to be solid and the tile will go to the ceiling. I have most of my materials on hand now (pending delivery) but will probably be making regular HD detours on the way home from work.

Tonight I will start on the process of lowering and reinforcing the floor. The unique thing about this project is probably the electrically heated floor continuous from room to sloping shower. Does this raise any red flags? Suntouch's installation pdf file says it can be installed in a shower and does not mention a 24V transformer. And I'm using Warmly Yours which looks very similar.

[Engineerly]

Bob (or anybody who cares to offer an opinion),

Does this seem like a sensible method and order to do the floor in?
A. Build/pack 90% of proper mudbed in shower floor (including packing under Kerdi drain)
B. Embed heating mat in mudbed while still "wet"
C. Top screed, final slope and finish of mudbed while hiding the mat and everything is still "wet".
D. Standback and admire handiwork while enjoying a Samuel Adams Boston Ale.
E. Next day pour and spread SLC over the rest of the heating mat on bathroom floor using the open edge of shower perimeter screed as a dam and level guide for the SLC (this step may require a sketch).
F. Let everything set up.
G. Apply Kerdi waterproof membrane over all using unmodified thinset.
H. Apply Tile, etc

My intention is that a lippage-free transition happens from the 12" floor tiles to the 4" shower tiles at the change of slope into the shower.

[bbcamp]

If your heater is attached to a fiberglass mat, you won't be able to embed it somewhere in the middle of your mud bed. It'll have to go on top or underneath. If you use the heating cable, you can embed it in mud. The fiberglass mat will effectively cut your mud bed, making 2 thin beds instead on one thick one.

You know, by the time you get your water adjusted to the temperatue you want, the floor will be warmed up.

[Engineerly]

Yeah, I read the comments about safety and turning on hot water for a few seconds before getting in. Those are valid points. But let's say we were going to do it anyway: since the wire can be detached from the mesh for that "free form" section, are you saying that snaking the meshless wire at the recommended 2" spacing below the surface of the mudbed would NOT compromise it's structural integrity? I wonder if that Warmly Yours rep wants to chime in?

[Engineerly]

I've received the WarmlyYours kit and read how that for first-time installers they recommend a two step application of thinset, once to stick it down and level it out even with the non heated areas and again to actually install the tile over everything. However, standard practice is to "burn in" the mortar to the substrate to ensure a good bond. So, can someone explain how you would do that with the plastic mesh in the way? This looks like a problem to me and since I don't want to be looking at a muddy mess over damaged wires, I'm leaning heavily towards the SLC approach.

Wade, I need your opinion on this.

[Engineerly]

I called the WarmlyYours tech support line and asked them the "burning in" question. He said if you make the thinset a bit runnier it will flow easier into all the mesh spaces and stick to the plywood floor without having to press too hard on the wires. Also (obviously) I should use only the straight edge of the trowel for that step. If I have large, non-heated areas on the same floor area, I'd have to put a skim coat down there to level out the height. He also suggested that SLC is easier since I'd be pushing around a milkshake rather than a blob of peanut butter.

I read elsewhere that an experienced tiler could put the base coat on the mat, build up the non-heated areas, backbutter the tile, and lay a lippage free floor in one pass. Whoa! To complicate things, I'm putting Kerdi between the heating mat and porcelain tile and need 100% contact which would be hard to do over a rough surface so I think that clinches the debate in favor of SLC. So, at this point I'm planning my bathroom floor sandwich to consist of heating mat, SLC, Kerabond dry-set, Kerdi, more Kerabond, 3/8" porcelain tile, grout. It will be a challenge to keep all that only 3/4" thick to match the adjacent hardwood floor.

In other news .... I'm pretty much done with my joist/flooring reinforcement, but can't close up my crawlspace until I finish my plumbing rough-in. Then there will be some electrical changes like adding a waterproof light above the shower, more lighting around the mirror above the sink and a new circuit and thermostat box for the heating mat. It's all "fun" but I have done zero tiling so far. Soon I will be doing my Mapei Opticolor grout test board and will show y'all a close-up of that. Also, today I may be buying (locally) a used Pro-Line Tile Saw with a 2.5HP motor and 10" blade. A bit overkill for my 4, 6, and 12" tiles but if I can calibrate it to cut straight it should do the job.

As usual, any and all comments and sanity checks are welcome.

Stay tuned,
Ron

[superchunk]

Hey Ron,

I wanted to reply to your previous post, but got side-tracked and then lost it.

Anyway, I did the skim coat over the W.Y. mat last month. I even did it with medium set, which has a courser sand. I was able to get it through the mesh without much of an issue. Also, if you have turns, the mat will get flipped and the mesh will be on the bottom of the wires.

However, I agree with you that SLC is the way to go. If my hallway floor was (nearly) level, I would have tried SLC. I was concerned about having my bathroom floor level where it met my unlevel hallway floor (~1/4" drop across the doorway).

I wouldn't worry too much about your door transition. Anything less than 1/2" difference and no one is even going to notice (with an appropriate transition piece). Heck, one of my friends bought a house with ~1 1/4" rise into their tiled kitchen. While that is unusual and noticeable, I never thought twice about it, until I started to think about my own tiling job.

[Engineerly]

Here's an update and a few pictures to show some progress and a few glimpses of the things you all know are part of a major bathroom remodeling project.


1. Fix the subfloor:

I jacked up and "sistered" this cracked joist as well as the ones under the shower, and added layer of 3/4" plywood from below using cleats to hold it up. That part is not shown in this picture.


2. Redo a bunch of plumbing:

This image also shows the grab-bar supports, the dropped floor and the 18x18x36 bench.


3. Change some wiring:

On the left is the new triple switch for the ceiling fan, shower light, and the main lights above the sink and mirror. The one of the right is the big box for the Warmly Yours thermostat.


4: Hang the cement backer board:

I used both Wonderboard and Durock for comparison and although the wonderboard is stiffer and denser, I actually prefer the Durock because it is easier to work with and the screws sunk in nicely. Most of the time on the Wonderboard, a hill was made around each screw which had to be scraped off.

The next steps are:
- Lay the heating mat on main floor area and spray the SLC primer under and over the mesh.
- Pour the SLC (LevelQuik ES) over the mat. I have already built most of my dam so the rest is up to gravity .
- Build the sloping mortar bed in the shower area (using John's dry deck mud recipe) while embedding the rest of the heating mat into it (without the mesh). This will be tricky because I'll need to make the shower entrance side flush with the main floor area and slope it nicely around the bench and I'm planning still to make the drain closer to the plumbing wall which will make the slope more complex. I'll be using 4" tile so expect it to conform with minor spacing adjustments as needed. Any tips or "how to" links here will be appreciated!
- Hang the Kerdi membrane
- Tile the walls
- Tile the floors
- Install fixtures, baseboards and trim

I'll try to keep you posted (and do that Opticolor Grout test asap).

-Ron