Walk-in shower, bathroom floor questions, first project [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-06-2007, 12:40 AM
Walk-in Shower
It started off as a simple remove the caulk and bleach the grout and re caulk. The grout was cracked all the way around the base so I decided to remove it and re grout. Well after a few tiles on the curb fell off and the drywall underneath was soaked. I felt it was necessary to do it right.

The house is 12 years old and we just moved in about 3 months ago. The plan for the masterbath is to redo the shower and while I am it, tile the floor. I removed everything that was once the shower. Mortar bed, membrane, plywood subfloor in shower that was scored and screwed down to create slope, drywall that was wet for the bottom 4-6 inches, curb....

The shower is 42" wide and 36" deep, walls on three sides with a glass door. I am using the Schluter shower kit for the entire shower install and using Fiberock in place of the old drywall that the builder used. I have access to the plumbing underneath as there is an interior crawlspace. I feel I have a pretty good hand on the shower or at least for now as I am in a holding pattern. Couple things though. Is it ok to crawl around and stand on the Kerdi membrane to tile the walls or should I put something down? cardboard...
Should I tile the shower floor first?

The bathroom floor was lino which has all been removed. There is 5/8" plywood flooring down, joists are 16" o/c, and a 3/8" subfloor on top of that(with lots of old glue on it). I have screwed the floor all over with floor screws and hit the joist on all. One person mentioned to add another 3/8" fir subfloor but when I got reading about Ditra it didn't seem necessary. Is this necessary?
I am waiting for the heating roll from 'Warmly Yours' to arrive. My main questions are regarding this.

Through reading all the advice on here I plan on putting the heating mat down next, then the Ditra, then tile. I keep hearing about SLC (self leveling compound) and having to use this. Is this necessary? The floor I am dealing with is 75 sq ft and the heating mat will cover 51.
What is the best way to level the floor once the mat is down? SLC?

The current plan is to use tiles 17.5x17.5 throughout the floor and shower. Are the Schluter movement and control joint profiles for where the wall meets the floor and the walls meet in the shower worth it? I also plan to use tile as a base board around bathroom floor. Approx 4" high. Would they be a good idea there? Either between the floor and baseboard or even the top of the baseboard to have a clean finish?

As I mentioned, I am waiting for the heating mat to come in so everything is on hold until then.

Any advice is greatly appreciated.


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03-06-2007, 12:40 PM
Welcome, Stacey! :wave:

sounds like we had the same shower builder. :sick: I'll take a shot at a couple of your questions.

good move going with Kerdi. Do you have the CBU up already? I know you're prolly gun shy about drywall, but it really does work behind Kerdi - and a lot easier to work with. :tup2:

best not to walk around too much on the Kerdi. Scrap drywall works great, or heavy cardboard will do.

most folks like to tile the walls first with the logic being that you don't want pookey dropping down on the new floor. It's really personal preference.

I'll leave the floor to others. :D

03-06-2007, 01:00 PM
Hi Stcy, :wave:

The SLC is not necessary it is an alternative method to placing the mat with thinset. If your floor is not flat you can flatten it and install the mat in one step using the SLC. With 17.5" tiles you really want flat. Emphasis on flat, to quote CX, tile wants flat don't care about level.

03-06-2007, 03:08 PM
thanks so far, couple more though.

I have the fiberock up already and it was very easy to work with, just a little heavier than drywall.

The SLC part.

Would it be best to lay the mat (warmly yours) down and staple to the floor and then simply pour the SLC over and around it? I take it the SLC is very thin and will be able to run through the mesh of the mat and fill all the voids? I read somewhere on here that you need a gap between the walls and the SLC. Is this true? And how thin or thick does the SLC layer have to be? Just enough to cover the mat and wires? Which would be approx 1/8"

thanks again


03-06-2007, 07:42 PM
Tracy, please take a look in the Liberry, we have a section on SLC and radiant. By the time you get the mat, plastic mesh and SLC down the floor elevation will be approximately 3/8" higher.

Is your floor flat? Best way is to take a straight edge and go around the floor with it.

03-07-2007, 03:51 PM
thanks Jim

I read your SLC part in the Liberry and you mentioned about removing all adhesives from the substrate. There was lino down before and the entire floor is covered with the old glue. Any tips for removing this prior to priming? I have tried in spots to scrape it off but that doesn't work very well. Does it have to come off?

You mention a plastic lathe over any type of wood floor. Is this for strength of the SLC? Would the fibreglass open weave mesh of the heating mat work for this. I will be stapling the heating mat down and the actual wire will be under the mat.

As for, is my floor flat? I uses a string line and can see a couple small dips, probably 1/8" at worst and fairly small areas. Thoughts?

Still waiting on the radiant heating so now is the time to get everything sorted out on what I need to do and don't need to do.

thanks again

03-07-2007, 04:23 PM
Stacy, what color is the glue? Try wetting it, let the water sit, see if it softens, and then scraping it with a razor scraper on a pole.

We would still like to see you go over the floor with a straight edge.

03-11-2007, 12:59 PM
The glue is a grey and white color I guess. You can't even see the wood throughout the bathroom. I have attached two pics of the floor.

I did go in with a straight edge. There are a couple areas when using the straight edge that are approximately 1/8" lower in spots. Is this a problem?

I also tried the water sitting on the glue and then scraping. It helps a little however I don't think I will ever see the color of the wood underneath the glue. Any other methods that may work better?
Will the glue pose a huge problem for the SLC?
Because of this, would it be better to use thinset over the heating mat and areas that are not being covered by the mat?
Still using Ditra over the mat and under the tile.
Still planning on using 18" porcelain tiles.

thanks again

03-11-2007, 03:48 PM
The glue is definitely a problem for a SLC. Perhaps someone else will advise on a thinset compatible with the glue.

BTW, have you run your structural data through the Deflecto?

Rd Tile
03-11-2007, 03:57 PM
I use Flexbond from HD all the time over cutback adhesive, not sure what you have there, I would've removed the 3/8 ply in question and then added new 1/2" ply., guess you can still throw down another layer of ply if you have the height, not crazy about 3/8" ply in any of my subfloors.:)

03-11-2007, 04:37 PM
I have ran it through Deflecto and came up with this reading. L / 458. Which is ok for tile.

Now I am really confused as what to do. :bang:

I don't really have the height to add another layer to the subfloor. You think I should rip out the 3/8" and replace with it with 1/2"? I don't want to get into why but that is a major issue on a number of points for me.

The simple plan to lay the radiant heating, thinset over this enough to cover the wires and mesh (1/8"), and then a similar amount where the mat is not, then lay the Ditra, tile etc..
Not a good idea? Trust me, I do want to do this the right way.

thanks again

John Bridge
03-11-2007, 05:25 PM
Hi Stacey,

You can give the glue the water test. Wet a small area and let it stand for half an hour or so. If the glue dissolves, remove it completely with water. If it does not, you can go over it with the type of thinset that RD tile recommends. I would imbed the heat mat in thin set and smooth it out over the wires. Then install the Ditra with thin set and finally the tiles. Large tiles can be leveled up somewhat with thin set.

03-12-2007, 06:30 PM
Getting ahead of myself a little as I am STILL waiting for the heating mat. :yawn:

Just purchased some rectified 18" x 18" porcelain tiles (R.A.K. Ceramics Gems collection). They have a polished finish. The guy at the tile store said with this type of tile to have a very small grout line. He used a Dime to show the spacing. Is this correct?

He mentioned to use an unsanded grout for this application. By reading other forums this is correct for the size. Are there any specific brands to go with or to steer clear of for unsanded grouts?

The color of the tile is dark charcoal. Any thoughts on color of grout? Black grout? A similar charcoal however it is lighter about the same amount the black is darker.


03-14-2007, 08:29 PM
bump :shrug:


03-14-2007, 09:13 PM
Whatever color you like, Stacy. Can't see it from my house.

Not bein' tacky, just making the point that it's a purely aesthetic choice, eh? :)

You get the glue off the subfloor?

03-15-2007, 08:00 AM
As for the glue...I have soaked it in water for approximately 1/2 hour and then attempted to scrape it off. The water definitely affects it however does not dissolve it. I have used water and gotten it wet in a few areas and the white portion comes off however the dark grey color remains. A substantial amount of scraping also went into it.

Is it worthwhile getting the white portion off?

Regarding my question about spacing for grout. Is it ok or is the tile store guy correct to say that the width of a dime is ok for these tiles?

many thanks again.

03-15-2007, 08:31 AM
Is it worthwhile getting the white portion off? I think so.

I know you said you really don't wanna, but I think you should give serious thought to removing the top layer of plywood and replacing it as Richie (Rd tile) suggested. Depending upon how it was installed, it's frequently not all that difficult to remove.Regarding my question about spacing for grout. Is it ok or is the tile store guy correct to say that the width of a dime is ok for these tiles?The smaller the grout joint, the more difficult the installation and the more critical the size and shape of the individual tiles. Some manufacturers' idea of "rectified" is a bit different than others. You get to a joint of a sixteenth of an inch or less on large-format tiles, you need for them to be nearly perfectly square, flat, and of identical size. I'd recommend a bit of time up front with a framing square to see just how close yours are.

My opinion; worth price charged.

03-18-2007, 04:13 PM
I have attached a couple floor pictures. I am not sure what it was on the floor. It was a lot of glue if that is what it was. I had to use a small plane and a few hours to get it all off. The floor scraper I picked up would not touch it.

I have gone through the floor with a straight edge and there are a couple places where it has approximately 1/8" drop. Now that the floor is clear, I should be able to use some SLC right? Or not worth it with only 1/8"?

Still awaiting delivery of the radiant heating mat. :rofl:


03-18-2007, 04:17 PM

03-20-2007, 06:05 PM

03-20-2007, 07:37 PM
I wouldn't bother with SLC for 1/8th-inch variations in plane.

What's the story on that patched-looking area?

My opinion; worth price charged.

And would you please go to the UserCP near the top of the page, find Edit Signature, and enter your first name for us there? :)

03-20-2007, 09:36 PM
thanks cx...I was a little intimidated by the SLC.

the patched area....

the original shower had a morter bed that was poured on top of the membrane. the membrane was on top of a chunk of plywood that was raised up on the outside and sliced underneath to created slope. it was screwed down all around the drain so the layer of plywood was attached to the floor while the outsides sat on top of strips of wood approximately 1" x 2". Anyways, it created a 3/8" deep missing piece where the shower was to go along with an ugly line to tie in with the current sub-floor. the patch simply made the transition smoother.

couple pics might explain better than my garble above.

will i incur any problems with that? :shrug:



03-20-2007, 10:19 PM
That gonna be a curb for the shower across there in the new world?

03-21-2007, 06:12 AM
Yes. Using the Schluter Shower Kit.


03-21-2007, 08:48 AM
This is a good thing. :)

Looks like you'll need a soft joint in the floor tile right there and that should work out fine.

My opinion; worth price charged.

04-02-2007, 10:00 AM
I have finally received the radiant heating pad (roll). The instructions are to install the roll on the floor (tape, glue gun, staples) and then to put thinset or SLC on it. The wire is only 1/8" thick however the company recommends putting at least 3/8" to act as a bed for the heat.

As the roll is being placed on plywood I am going to use a modified thinset (Versabond).
I will then place Ditra over this 'bed' and then the tile.
I will be doing this in two stages, ie. 3/8" thinset over heat roll, cure, then more thinset and Ditra.

My questions are:

Does this sound ok to do it this way?

When I put my next layer of thinset down for the Ditra, what kind should I use? Non-modifed right? as it is bonding between the fleece and the other thinset.


04-03-2007, 08:13 AM
No, doesn't sound like a good way to moi. That's way too thick to be applying VersaBond or similar thinset. SLC, yes.

You can maybe do that with a medium-bed thinset of some kind, but check with the manufacturer on that particular application.

If you skim-coat over the heating mat with the modified thinset, you must still install the Ditra with un-modified thinset according to the manufacturer.

My opinion; worth price charged.

04-08-2007, 10:15 AM
I have a couple questions regarding grouting and laying tile.

My plan is to use tile instead of any base board moulding in the bathroom. My question is...

Do I grout the tile on the floor first and then install the tile pieces on the wall and then grout them later on their own? Or do I install everything at once and grout all of it after?

I also want to confirm that anywhere the tile meets at 90 degrees....
the floor tile meeting the wall tile or the corners in the shower....I want to caulk that area right and leave it free of grout?

thanks again.

:yipee: the project is moving along. i have the shower kit fully installed, the radiant heating done(skim coated with versabond then unmodified thinset to put the ditra down) and have some tile down. just making some cuts and installing the rest of the floor tile....the shower will be next.


04-09-2007, 08:50 PM
bump :shrug:


04-10-2007, 07:42 AM
You can do that in either order, Stacey. If you grout the floor first, you need to cover it to keep it clean while you set and finish your baseboard. In any case, you need to keep the joint between base and floor clear for caulking.

Yes, you caulk all changes of plane in the shower and yes you leave those joints open (no grout).

My opinion; worth price charged.

04-10-2007, 04:56 PM
Awesome. Thanks cx. Just purchased my grout from the nearby tile store and noted that it is Polymer modified wall grout (Flextile). I told him in the store what it was for. The floor and walls of the shower.

Is this going to be ok??

And thanks for the no grout advice in changes in plane. I asked him at the tile store and he said I could do either but grout would look better. When asked about the possible movement he stated there should not be much. This visit was done prior to your advice above. As I read somewhere on this site that said something like 80% of people installing tile do it wrong and grount inside corners and changes in plane. I will find some color matching caulk. thanks :tup2:

Grout is charcoal color.

thanks again.


04-10-2007, 05:49 PM
As I read somewhere on this site that said something like 80% of people installing tile do it wrong and grount inside corners and changes in plane.I'm one of the 80%. :)

I think you'll find that nearly all cementitious grouts today are modified. You'd hafta specify brand and type to get any opinions from our knowledgeable tile guys.

My opinion; worth price charged.

04-21-2007, 12:46 PM
Finished the floor and will put some pics shortly.

My question is on tiling the shower. I am using the same tiles, 18x18, and am wondering if I should do it in stages. ie. 2 rows then wait, then 2 more etc. The shower will be 5 tiles high. 2 full tiles on each side wall and 2 full plus a 5 inch wide tile on the back.

Is it possible to keep going right up to the 5 tiles high or will it be to much weight on the lower tiles?

Thanks again.