Slate Shower [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-15-2010, 01:03 PM
O.k. guys after much back and forth with the wife, we went back to plan A and are doing to 2x2" slate on mesh for the shower floor even though I understand the continuing maintenance this will require.
I read a few threads here about RedGuard liquid membrane and coated the durarock walls and the pre-sloped concrete floor this weekend and I can definately say I am impressed with that stuff....anyone disagree?
So I have a couple questions for you fellas that have really been helpful throughout this process:
1. is the redguard a suitable surface to adhere the slate sheets to? Any prep to the surface needed?
2. What size trowel should I use for the floor sheets of 2x2" slate? 1/4" v-groove?
3. Is there a reason I cannot find a bag of thinset anywhere that explicitly says somewhere on it that it's approved for moist areas/showers?
There are about 10 varieties of thinset at my local big box but none that say approved for showers/moist/ wet areas. Am I missing something?
Or do I just grab a bag of "modified thinset". I think the line is called Versa bond? How about the liquid hardener that they sell to replace the water mix....good idea?
Thanks again in advance.

One more:
Sanded or unsanded grout for the 2x2" sheets? The joints between the slates are 1/8" max.

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02-15-2010, 01:11 PM
1) Redgard is a suitable substrate for tiles of almost any kind. However, for your shower floor, I don't recommend it. Install a PVC liner, your backerboard (taped and mudded and coated with 2 coars of Redgard) then place your setting bed. Redgard will prevent the setting bed from drying out easily. Water will get into it, so you want the bed to be able to breathe as well as drain.

2) Yep, smallish v-groove. Check your coverage as you tile.

3) Thinset bags will not say "approved for wet areas." Instead, the bag will say meets ANSI something or other, etc. You want one that says ANSI A118.11. Versabond is such an animal. It does not need, nor want, the special admix. Just use water.

02-15-2010, 01:32 PM
Thanks Bob!
There is a PVC liner below my sloped concrete that a plumber put in over a 1 yr ago which is why I decided to go w/the redguard.
Here's the sandwich: flat concrete slab, pvc liner, sloped concrete, 3 coats of redguard.
I saw in previous threads that the pvc liner should have been put on top of the pre-sloped concrete which is what lead to me coating the floor with the Redguard. I figured that stuff would keep the moisture off of the pre-sloped because it's an approved liner in some areas?
how about the grout for the 1/8" spaces?-sanded/non? Is it logical to think that with all the maintenance the slate is going to require that I should use the stronger grout which I'm assuming would be the sanded?

02-17-2010, 03:55 PM
I don't know what I would have done without this forum, the info gathered here has been priceless but sometimes contradicting which is completely understandable when you have such a wide group of professionals and inputs.
A very sincere Thank you to all.
....on to the next step!
I laid the 2x2" tumbled slate shower floor yesterday and I must say I am very pleased with how it turned out.
I know everyone is cursing me for going ahead with the slate but I am extremely o.k. with continual maintenance for what I got, it is going to look awesome.
Any recommendations for a great sealer before and after I grout? I would prefer the shiny "wet" look but cant locate a brand that is for wet areas? Everything for wet areas seems to be a matte finish, penetrating sealer.

John Bridge
02-17-2010, 03:57 PM
Hi Jason, :)

Use a penetrating sealer. Miracle Seal at Home Depot is fine. :)

02-17-2010, 04:54 PM
You may want to coat just the top of the stone with the sealer before you grout to help prevent the grout from clinging to the clefts in the slate..dont let the grout sit to long it can be a liitle hard to clean off..but mosaics generally dont have many clefts so they will be easier.

02-17-2010, 07:27 PM
Thanks again guys.....I'll be back I'm sure.
As a matter of fact, as long as I'm here, mind if I toss another one out there?
working with the thinset setting the floor slate yesterday really got me to think how the heck I'm going to be able to keep the larger wall tiles in place while the thinset sets up?
I'm pretty sure I had the right mix per the bag insrtuctions (6 qts of h2o per 50 lb. bag) and the mix was like a peanut butter consistency and I let it "slake"(?) for 10-15 minutes before I started putting it down, but gosh darn it, the 12x12" slates on mesh were still sliding toward the drain for a good hour or so with the minor 1/4" per ft. pre-sloped.
What's the trick to keeping them in place on the shower walls?
I've seen threads here about tacking temporary nails in but wouldn't that just defeat all my effort and work coating the walls with the redguard?, there should really be a cold beer icon here for me to send to all of you for the help!....wait a second, here we go :cheers:

Houston Remodeler
02-17-2010, 07:32 PM
The floor tiles were sliding ??

02-17-2010, 07:35 PM
the 12x12" slates on mesh were still sliding toward the drain for a good hour or so with the minor 1/4" per ft. pre-sloped.

That aint right...sumthing wrong with that. Anyone have a guess?

Spacers and wedges and occasional blue tape are how we usually keep from sliding on walls.

02-17-2010, 07:37 PM
Yeah, not too much, but the one sheet closest to the drain where I started kept sliding slightly off kilter, down toward the drain. Only moved about 1/8" but I had to keep readjusting it for about an hr before it stayed in place.
....thinset too thin?

Houston Remodeler
02-17-2010, 07:40 PM
The only way floor tiles could shift on a normally sloped shower floor is if the thinset was far too runny and the tiles were not "set" into the thinset. This would also explain why it took so long for the thinset to set. I am thinking these tiles will be popping off by themselves in short order.

Slippage on the walls - I think Henry aka Laticrete has 4XLT to solve that problem.

Perhaps this is one of those "enhanced gravity zones" ? Does Stephen Hawking know about this?

02-17-2010, 08:04 PM
could I have been using to much thinset?
I sure thought I was doing everything right-i.e. thin smooth coat on the floor then v grooved 3/16" layer of thinset. Then patting them down with a little force using my float...maybe even a bit to much force as I had quite a bit of thinset coming up between the slates until I got the right touch.
Should I: A) let them set another day or so and try pop a few of the 2x2" slates up to see if they held?...or B) rip it up and start over?! (please not B).
Plus, again, I measured and mixed exactly to the instructions on the bag of versabond.
Boy, I certainly didn't think I'd have to worry about the good 'ol boys from versabond misleading me?!

02-17-2010, 08:43 PM
Sounds like you did it right...maybe you mixed too runny..but you said peanut butter so that doesnt sound too runny. and if careful tamping doesn't bring the thinset up through the joints but too much tamping does ..that sounds right also. You sure you weren't just hallucinating when I think you saw it slide:crazy:

Well if it looks good now(bonded) then lets just pretend it didn't happen..besides once the grout gets in there it will lock things up even more.

Prop up a ledger board around the base and make sure it is level..and make it the right height to have a good layout then just stack them part way up and goto the next wall...start the back wall first..don't stack too high at one time or the spacers will crush(unless you use hard spacers.

02-17-2010, 09:12 PM
Jim- you da man!
I'd definitely be willing to chalk it up to a hallucination.
I just went down and carefully tried moving/lifting a few random tiles and those suckers ain't moving at all after 24 hrs! whew...that's a bit reassuring.
Thanks for the tips on the walls, I'll give it a go once I seal and grout the floor this weekend.
Thanks a million

02-17-2010, 09:22 PM
if your grouting the floor the same color just wait till you do the walls and grout all at will end up with 10 lbs of dropped grout anyways..just rub in and wash after the walls are done.

02-18-2010, 08:22 AM
interesting...Jason...disclaimer: i'm no pro, just a diy'er learning from this site as i do my master bath. but i had a similar (only different :) ) experience.

on my walls (6X6 tiles), about 3 foot up, i did a row of mosaics as an accent row.

at one point as i was putting some of them on, a section of them would not stay put, but kept sliding UP the wall!

Well i was just about to call Steven Hawking proclaiming i had discovered 'anti gravity' when i realized that it was just the mesh backing. in one spot the backing was trying to hold the tiles at a wider spacing than the mosaics on either side of it. so when i correctly spaced it at the bottom and then pushed it into the thinset aligned with it's surroundings and then took my hands off, it would slowly expand to it's 'natural' size and UP was the only way to go.

since this was in a dry area and i was basically done for the day, i just took my level as a straightedge and pushed it down in line and put a couple nails above the level to hold it down and as the thinset hardened, everything came out fine.

anyway, you might have had a similar experience with the mesh trying to move your tiles.......

02-18-2010, 08:46 AM
JC- thank you kindly Sir for your assistance. This is really a wonderful resource for us DIY'ers. In the past, I would ask questions at my local HD....and then do the exact opposite of they said!
Good point- I'll hold off on the grouting. What type of grout would you recommend for the shower floor? The spacing between the 2x2" tumbled slates are 1/16"-1/8" max...some are pretty tight.
I'm thinking some form of the Laticrete grout...epoxy?... cement base?...sanded?...unsanded?... a thread poster pointed in the Laticrete direction. From what I can research online, it looks like a good product but confusing as to which product is for my app.

Dsoniat-thanks buddy, glad to know I'm not the only one living in a parallel universe!

02-18-2010, 12:41 PM
at one point as i was putting some of them on, a section of them would not stay put, but kept sliding UP the wall!

Must be something in the water?? j/k i know how that mesh does that.

spectralock would be nice for the floor it will fill those size joints..and give it a sealed property also(although not rated as a sealer it seems to seal also.

If not then use sanded grout..alot of guys like permacolor. if you go this route you will need additional sealing afterwards.(grout and the slate).

You did not mention what tile is going to be on the wall(i think)..the walls do not have to be the same grout as the floor either..but type of tile will help determine type of grout.

02-18-2010, 03:19 PM
Well JC, we found beautiful 12"x12" "Terra Red" slate from India at my local tile house that we think would go well with the mosaic slate floor.
I have a couple of them soaking in my slop sink to see how they hold up to moisture.....I learned that tip from the forum here!
They are a very rough, uneven surfaced tile (which we like) but I have noticed that they seem to shale off a layer easier than the other Vermont varieties we've been looking at, which causes me some concern.
hey also feel a bit heavier/dense than some of the others which is why I was concerned about them sliding down the wall when I go to install them.

Is the spectralock easy to work with? compared to standard sanded grout?

02-18-2010, 06:38 PM
spectralock is a little bit harder..but only a little bit. with the floor mosaic you should be fine.

However I think I know of the red slate your talking about and if its what I think it is you will be having a hard time grouting it.

Is there a way you can get some close-up hi-def pictures of it?

The inherent problem with slate is that grout gets stuck in the clefts and in some cases some slate(possibly your red) can have very rough surfaces spots that are next to impossible to grout with any grout. There are ways around this but first lets make sure what the tile looks like.

Take the slate out of the water..that test is for another type of stone not slate...slate won't warp.

Also need to know if the slate you intend to get is gauged or un-gauged as that can greatly affect installation difficulty.

02-18-2010, 07:07 PM, I'm really displaying my technological handicap. I don't see how to upload photos but I'll figure it out and post some.
I was wrong about the name of the wall slates- "Raja Red" is the name of the color we like and they are from India.
The only reason I've been waterboarding them is because I've read a few threads here that say it's a good way to tell if a slate is shower worthy.
I soaked a slate I picked up from Menards last week and it actually crumbled apart it the bucket!
Gauged/ungauged?....does that refer to the thickness or perimeter cut?
I should clarify a little better. The surface is really irregular, not so much rough. Alot of ridges and clefts. I can definitely see your point about grouting them and was contemplating using a grout bag to try and keep it in the grooves as much as possible.
I'll post some pis as soon as I figure out how to upload them.

02-18-2010, 08:34 PM
Ive never heard of testing them for the shower..heard of other types warping. but your saying they can fall apart with going to have to research that myself.

I hope your wrong cause Ive done quite a few slate far none of them fell apart though. Ive been careful to not use pieces that made hollow sounds though.

Gauging is a process where they grind down the backs of the stone to "help" make them close to the same thickness. You can usually look at the backs and see obvious grind marks if they are gauged.

Some ungauged slate can range easily from 1" thick to a 1/4" . So in order to get a semi flat job you have to...well how can I put this...know what your doing.
It involves adding and subtracting mortar to get them looking good. It is something that is practiced over and over again and is what separates a real stone setter from a garden variety ceramic guy.

They have systems like TLS and Lash to help guys get natural stone flat but those systems only work if the stone is the same thickness.

You can do it yourself it will be a learning experience and will be tedious figuring out when/where and how much cement to add and subtract. And how good it will come out depends entirely on how much patience you have. But then if all else fails you can always lower your standards. At least you can't trip over it if its on a wall.

This is true with both gauged and un-gauged but the gauged is less evil.

Also you know with a stone such as this you need to order extra to allow for "ugly" ones and ones that break and much extra depends on the quality of the stone.
I advise some customers to pick through and separate the stones right in the store if it comes from a box store..and we save the boxes to put the rejects in to take them back...not very ethical I know but hey if the box stores had better stone then maybe people would not have to buy 14 boxes when they only needed 10.

This site has all the software to store and post pics in house,just do some exploring.

A grout bag is a good way but you still might want to tape off a few till you get the feel of the grout bag.

Houston Remodeler
02-18-2010, 11:20 PM
LASH works well with tiles of different thicknesses.

TLS needs tiles of all the same thickness.

02-19-2010, 01:16 AM
Lash can handle as much as 3/8 difference? Have you tried it with slate?..don't seem like it would work that will..I mean its not a matter of getting an edge flat its more like your always splitting the difference to keep the high bumps low and the low spots from being to low. I don't see it.

02-19-2010, 09:15 AM
I here what your saying about the possibility of the uneven-ness of the slate. It is partially the reason I am into the whole slate look.
The few tiles I have as sample do have grooves on the back of them so I assume they are Gauged. thickness is about 3/8"-5/8" at the high points.
I think what your saying in regard to the wall tile is that I'll be needing to do alot of "backbuttering" to get the tiles set properly on the walls?

The "unstructured" look with (hopefully) semi-clean, semi- straight grout lines is what I'm going for in this shower. If it was our primary, main floor bathroom I would probably be doing a more clean, uniform tile but this bathroom is in my basement which I've remodeled into bar/rec room and the shower is in a bathroom next to a urinal!...still can't believe the wife let me get away with that one!
So I'm going for total mancave deco. here....I want to feel like I'm standing in a cave underneath a waterfall in this shower.

I think I've figured out how to attach a few pics here to show the Raja Red 12x12" slate we're thinking about doing for the shower walls:
Also, I was reading up on the Spectralock grout...quite a few more steps involved but if it's a superior product to the standard cement based I'll go for it.

Houston Remodeler
02-19-2010, 06:21 PM
The LASH can handle slate and I have used it for slate before. As far as 3/8" difference, I can't say because that would depend on the thinness of the thinner tile then add 3/8 to that, it would have to be less than the maximum thickness that LASH can handle. TLS can take much larger thicknesses, but not differing thicknesses, Hence, its why I use both systems.

02-20-2010, 09:52 PM
paul, oh ok, guess ill just have try you think there would be a problem with hollow spots? I wouldnt want to mix the mortar too wet if I have to do alot of biuld up with the thinner pieces.. An ungauged slate kinda scares me. should I be?

Jason that doesn't look too bad for roughness. I also like the "mancave look":)

Regular grout may be a little easier..maybe spectrolock the floor first..see how you like it then decide if you want to use it for the wall or not.

A few coats of sealer to the tops of the tile will help out, also if you wipe a damp sponge across the surface right before you spread the grout on that spot it will help..and just do small sections and don't let the get have over..wipe on wipe should be alright...
Also having a little grout in the clefts is almost considered acceptable for the over all look(personal taste..and may even keep water and or make it durable)..if you want to look at it that way. Ive done slate im imitation tile where they had a look of grout in the clefts..I usually get it as clean as possible though personally.

heres a mancave bath i did with slate floors:

Houston Remodeler
02-20-2010, 11:22 PM
Yes, un-gauged slate takes a bit more work and skill to install than gauged. Expect to be removing a few tiles as you go to get the right amount of thinset, medium set below each tile to get them all to match without stubbing a toe.

Gauged slate costs more to buy usually, but less effort to install. What is the going rate at the chiropractors office?

02-21-2010, 12:35 AM
Yea I did 400 ft in a square room over the summer of crappy box store slate..took two days to set..but they were LONG HARD days...when I get tired I start getting messy and lifting the tile more often then I should. On your knees for 12 hours is a killer fer sure.

Brian in San Diego
02-21-2010, 08:48 AM
I did some research on slate designations a few years back. I will bet most of the slate sold at the big box stores is gauged. All that means in the slate world is that one side is flat. It has absolutely nothing to do with the thickness of the tile. So you could get a box of gauged slate and every tile could be of a different thickness. The next designation they used is gauged and calibrated. This means that all the tiles are flat on one side and are all the same thickness (+/- an amount I don't recall). The next designation is honed and calibrated. These tile will be as close as one can get to uniform for slate. They will be flat, calibrated and the surface will be honed smooth and will have sharp square edges. As the uniformity goes up so does the price. You are not going to get honed and calibrated slate for big box store prices. Generally you'll find it's going to be in the $6+/sq.ft. range.

02-21-2010, 03:21 PM
JC- good work my man, quite the stonework in that bath!
got a question: I noticed that the drain screen in the floor of the shower appears to be setting on top of the slate mosiacs? I have the same situation going on in my shower where drain screen/cover is even with the top of the tile on one side but ever so slightly (1/16") above the slate on the other side.
I was concerned that it might hamper the drainage so I was going to take a grinder to the metal drain bowl under the screen and cut out grooves around the perimeter of it so the water that runs under the screen can escape down the drain. Sound logical or not a good idea?

02-21-2010, 05:48 PM
thx Jason, No the drain just looks that way a little, that is cheap lowes mosaics.. pain when one sheet is higher then the others on mosaics cause there is no building up and you have to just arrange them the best you can to avoid lippage, its not above the slate the slate abutts it.. actually I trace the drain lid the the slate,use a grinder to get it close, then I use a water router(made for stain glass work) to get it exact.

Your plan to cut the drain should work fine and keep away standing water.

02-23-2010, 02:23 PM
Hey guys...just trying to think ahead here, got a Spectralock query:
If I do the Spectralock epoxy grout on my 2x2" slate mosaic shower floor that will need to be consistently and frequently resealed, will the spectralock be affected by the penetrating sealer?
Will I be actually gaining anything by using the spectralock if I am very devout in resealing the shower every year?...or would I be better of using the regular cementitous grout as long as I'm going to be resealing so often.

Also, I was at my tile store yesterday and ordered my Raja Red slate for the shower walls and asked the nice fella what thinset he had/recommended.
His response was "White for walls, gray for floors. The white will hold the slates up, the gray will allow them to slide down before the thinset sets up"
Does this sound just sounded too made up to me?

02-23-2010, 03:30 PM
If I do the Spectralock epoxy grout on my 2x2" slate mosaic shower floor that will need to be consistently and frequently resealed, will the spectralock be affected by the penetrating sealer?

That a good question and one I often pondered.

The spectrolock even though it is not technically a sealer will seal to an extent the surface of the much and how long it last I dunno.

obviously with spectrolock the grout joint wont need sealed your concern is the stone itself.

I would say that if you use the spectrolock you can always do a test with water to see if you need to use a penetrating sealer..if it absorbs then seal it.

or just use a good sealer on everything

The guy at the tile store doesn't have a clue..You can use white or gray...they ARE exactly the same except for color.

However the Marble and granite set is is white because it could be used with certain stones that will absorb residual moisture and become stained by a gray thinset(white marble is one example). Your slate wont care what color you use.

The real reason you will want to use the white(only color it comes in) marble and granite set is because it is whats considered a "medium set" as opposed to "thinset". This simply means it has bigger size sand in it and that is what allows you to use bigger notches and it reduces settling when as it dries.

There are also some other mortars you can use that allow for 1/2 or bigger notches but the marble and granite set is easily available at home stores.

So use a medium set for the walls, and gray or white for the floors...and yes you can use the medium set for the floor too if you rather not buy a whole bag of thinset for the small area...just mix it a little loose though to get it to spread better and bond better.

02-24-2010, 07:57 PM
O.k. gents, one last question as I prepare for my battle this might be a silly one:
Is there any proper rhyme or reason to matching the grooves on the back of the slates with the medium-set trowel groove pattern on the walls?
That doesn't sound right, let me try it again another way:
Should I apply the medium set mortar with the trowel grooves parallel with or against the grooves on the back side of the slates? Does one way bond or hold better than the other or it makes no difference?

Brian in San Diego
02-24-2010, 10:07 PM

Believe it or not it isn't that silly. The proper way to comb thinset is all in the same direction and that's so air can escape when the tile is "set" into the mortar. Keeping with that theory you might want to keep them in the same direction. In reality, I don't think the grooves in the bottom of the slate would be deep enough to counteract the thinset ridges.

Keep your thinset combed in one direction and I would set the tile so that there is minimum lippage between tiles...let the grooves fall where they may.


Houston Remodeler
02-24-2010, 11:25 PM
the bestest thing to do is to 'back butter' or 'burn in' the slate. Apply a slathering of mortar and then using the flat edge of the trowel, scrape off in the direction on the ridges so that you fill all the nooks and crannies then lay the tile as usual

02-25-2010, 09:53 AM
great advice, Thanks again for all the help.
minimum lippage?....lippage = mortar between tiles?

02-25-2010, 10:18 AM
Lippage is where one tile sits higher than it's neighbor. If bad enough, it's a tripping hazard.

Houston Remodeler
02-25-2010, 06:59 PM
You can help eliminate lippage by using LASH or TLS

Lash = available at home depot

tls = tuscan leveling system

03-05-2010, 12:21 PM
Greetings all, thought I would post an update and pose a question for you professionals:

Installed the slate mosiac 2x2" floor- looks awesome, installed the 12x12" raja red slates on the shower walls and it looks awesomer!
I'll get some pics posted a.s.a.p. for the professional critque.

I am planning on grouting everything this weekend and have a sealing dilemma.
I have both Miracle Seal products (color enhancer/sealer & penetrating sealer) on hand and am wondering if I use the color enhancer/sealer before grouting as a grout release will I then be able to apply the penetrating sealer over everything once the grouting is completed?
I was planning on re-applying the penetrating sealer in numerous coats until it stopped being absorbed due to all the fore-warnings I've received here, but am concerned it won't absorb through the color enhancer/sealer.
I was really hoping the fine folks at Miracle seal would've made the color enhancer with the penetrating sealer but no such luck.
I did a few test areas comparing the 2 products and the color enhancer/sealer definitely does a better job livening up the slate colors as opposed to the penetrating sealer.
Anyone have experience mixing the 2 products?