Slate Flooring Installation

is grouting absolutely necessary in installing slate tiles as woodstove hearth? 5x5 ft hearth

It is if the underlayment is combustible.

I am istalling slate flooring in the basement bathroom. It is 12X12 tiles. Can I install the floor without grout joints?

Lynn,
Yes you can, but you will have issues. Read all of my columns about grouting. It is not too hard. In January, 2008 I will have a step-by-step photo guide showing how to do this.

Hi. We installed slate tiles on our kitchen floor. We used Hardibacker cement board as the sub-floor and kind of guessed our way through the process. With our inexperience, we didnt use spacers and used the thinset as the grout...and didn't seal the tiles before we did any of that. So now we have a bunch of dried excess grout on the tiles and in the crevesces of the tiles. Any advice for how to get the excess, dried grout off the tiles? Please help.

Krysti,
They say timing is everything. You have a real mess here and it is going to take some effort to correct it. I have a past column or two on Grout Removal. Read those and see if they work. Try your efforts on slate at the edge of the room. You can scratch the surface of slate, so proceed with caution.

I am Planning to install 12" slate on a concrete basement floor. Grout joints or not. You mentioned sealing before grouting. Is that necessary? What about the edges being sealed before grouting. Won't that create an adhesion problem. This slate is rather uneven. I dont mind the roughness but want to make the best decisson on these grout lines. Thank you

Robert,
If you fail to seal before you grout, you will work hard to remove the grout. Sealer on the edges will not be a problem.

ATB,
We love slate and are wondering if slate would work okay on shower walls and ceiling. Thank you so much!
alan

Alan,
It would be a material I would not use as it can be really tough to clean. Smooth surfaces in showers are the easiest to clean.

I plan on using 12x12 slate in my kitchen remodel and presantly have linoleum. I have used 1/4" plywood to go over the top with ceramic tile in the past and it has worked out well.- Can I do this with slate?? I will have the required 1 1/4" thickness over the floor joists with linoleum in between. Or can I use the crack isolation fabric directly over the linoleum?? Once sealed is slate hard to clean??

Jeff,
I would only use the plywood as a last resort. I have used it under my own slate, but now there are thin gypsum or cement products available. Slate is very easy to clean.

I have just installed a new slate floor in our kitchen. Before the grouting process, I sealed the tiles following the instructions. I grouted the floor and have cleaned the gray haze multiple times. When the floor is wet it looks perfect, but when it is dry you can see gray grout in the tiles. I have scrubbed with everything to try and clean. How can I clean this off before I seal the floor for the last time.

Todd,
Try using a stiffer scrub brush.

Hello,

I am about to do a slate floor in my kitchen. You said to seal the floor before grout (which is a great idea). I was wondering if it's ok that the sealer (liquid) gets in between the slate and what not? Will this create any grout adhesion issues?

Thanks!!!

Luke,
It is not an issue if some of the sealer gets on the edges of the slate.

I used slate in my house it looks great. Now I like to use it on my out sideporch. I have 3/4 water treaded plywood and 1/4 cement board. Will I have any problems with rain,snow and the extreme temps. we have in Minnesota.

Al,
The only issue I can see is if the cement board somehow detaches over time from the plywood. You must do a fantastic job with stainless-steel screws.

There will be a signigicant height difference between my slate floor and ajoining wood floors. What is the best thing to use to transition between the two as to not create a "stumbling block"?

Robert,
Why???????????? Tell me *why* the contractor is not installing an underlayment beneath the slate so the finished floors are flush.

Can the slate be sealed AFTER the grout is applied and dry? A fast answer is appreciated.
Thanks, Ula

Ula,
Yes.

Hello:
Can I install a slate floor directly on top of an existing sound 3 1/4 wide tongue
and grooved floor?
I would also like to use a ready mixed floor adhesive for ceramic and slate vs thin-set what are the pitfalls of this choice.

Thanks:Jim

I installed slate tiles in thin set over a concrete subfloor in a semi-outdoor environment (screened in porch). Before I could get it sealed and grouted, we had a couple days of torrential rain (Florida) and the tile and fairly dried thin set got wet. How long should I wait for it to dry before I seal and grout it? Is my project ruined because it got all wet before I put in the grout? Thanks.

I am about to install 12x12 slate in our entranceway and hall. Currently there is a layer of linoleum from the late 80's, then a 1/4" sheet of plywood, then some old vinyl probably from the early 70's (and probably has asbestos), and then the 1/2 sub-flooring. The framing below is very robust so the floor is very stiff. I don't want to mess with the asbestos vinyl. If I lay the concrete backer board on top of the 1/4" plywood, the floor is becoming excessively higher than the adjoining hardwood floors. Can I pull up the linoleum and 1/4 sheet of plywood and lay the concrete backer board directly on the old vinyl? If not, can I skip the backer board and lay the slate right on the old 1/4" plywood?

We are going to install 12 x 12 slate throughout our house. We are on a poured slab with no subflooring. What do we need to do to prep before we apply the tile?

I recently grouted a slate floor but now there's a haze on the floor.How do i remove it to seal the floor?

Jim,
It depends on whether there is a good subfloor under the finished flooring. You need to go read my past columns about Ceramic Tile and Wood Floors. I would absolutely consider a crack-isolation fabric and possibly a thin backerboard.

Esra,
The rain helped you! It allowed the thinset to cure. Once all the liquid water is gone, wait a day and then grout it.

Andrew,
You need to read all of my past columns about installing slate and ceramic tile. It will be well worth it.

Louise Ann,
Clean the concrete.

Joe,
Read my past columns about Removing Excess Grout.

Hello. I am about to start tiling my kitchen floor with a slate tile. I have quite a bit of tiling experience, but only one previous experience with using slate. Cleaning the grout off the slate was a painful process and was possible the more difficult task vs. the actual tiling or grouting. In the end, the floor came out beautiful, so it was worth it. I also have a limestone experience in which I used a grout release sealant, prior to grouting, but the grout removal was still very difficult. In both cases, I feel it wasn’t so much the grout removal that was difficult, but rather removing the stains from the grout color. For my new slate project, I was thinking I would use a wet look sealer prior to grouting as you recommended in a comment here. A wet look sealer is not my choice of final sealant, as I want a matte, enhanced look. But I figured I would strip the floor from the wet look sealer and then apply my final sealant. However, when I ran this idea by the company I bought the slate from (Ann Sacks), they said the stripping process would be very difficult with slate, and I should just use my end sealant product prior to grouting, which I’m thinking will be Miracle, Porous Plus. Can you please advise on your thoughts? Thank you.

Brian,
I think you should just follow the advice I have in the columns to get some sweet results.

I've read that you seal slate/grout AFTER grouting, then above you say to seal BEFORE grouting. Which is best and why?

Nancy

Nancy,
I state my reasons in all of my columns. You have to decide. I know what is best for me....... Surely you saw in my work where I said it is sealed both before and after grouting.

what type of sealer do you recommend for slate floors before grouting

i was thinking of installing slate in my kitchen. currently there is vinyl tile over a plywood subfoor which was set over the traditional hardwood floors. do i need to put an additional subfloor in or will this be sufficient if the total is 1.5 inches?

We recently purchased a 40+ year-old house with a Vermont slate foyer. The slate has been sealed at some point. We would like to strip and reseal the foyer. How can we determine what type of sealer was used and the best methods/products for stripping and resealing.

Thank you, in advance, for your help.

Jannine,
One that says on the label it is indeed a grout-release product.

Tony,
You are good to go.

Askthebuilder - I am now complete with the new slate floor in my kitchen. I sealed the slate before and after grouting. I want to add a few coats of high-gloss sealer to bring out the color. How is the high gloss sealer re: 1. durability 2. application on top of existing sealer 3. brand Thank you for your expert opinion.
Paul

Carol,
I would think you would have to do expensive qualitative chemical analysis. Call a few current sealer companies and see what they say to use to strip the floor. Maybe you have to use a commercial floor stripper used to take the finish off of vinyl-tile floors.

We have slate installed in our basement (fine), our walk up to our house (fine) and our outdoor decks (disintegrating). We have them professionally sealed every year (tell them the story and ask for best penetrating sealer, seems best to leave a thick cover of gloss on top to protect), then the sealant appears gone and the slate starts sloughing layers within months. Its always a mess, dirty, looks bad, and the layer of stone in many places is now well below the grout. We're about ready to give up on it, but don't know if there's like a thick polyurethane we could pour over, a rubberized cement, anything to stop the constant "yuck" of disintegrating slate... any suggestions? We do face the ocean in Southern California..

We recently added a stacked slate wall and built a hearth out from the fireplace base which was capped with 20x20" slate pieces. We grouted all the seams and were told to leave the grout for approx 2 hours. After the 2 hours I went to remove the excess with a wet sponge but unfortunately there was a huge mess left on all the edges of every seam. I have tried using a drillbit grinding stone but it leaves the slate with grey marks. Do you have any ideas as to how I can remove this excess grout without ruing the slate capstones?

Paul,
Some of the sealers are excellent. Let price be your North Star in the search.

I am going to install 12" x 12" square slate tiles (1 1/2" individual tiles glued to a mesh). What size thinset trowel grooves do you recomend so the cement won't ooze up between the tiles to much?

I am repairing my hearth. It is slate, and was cracked. I pulled it up and there is some backboard underneath (feels like masonite..but I'm sure it's not). I'm sure it's there for heat reasons.

can you tell me what would be used over plywood subfloor and under slate for a hearth?

I am installing slate tiles on an outside prexisting concrete floor, I was planning on using 1/4 or 3/8 tile spacers and using some of the morter to place in between the tiles like grout but lower and form a valley so I could then plant moss for a nice oudoors look. Do you have any suggestions? concerns? help? and what about the sealing issue is that something that is good outdoors too?
Should I not install pieces that are eroding already even though they look very character like and outdoorzy?

Hey there Im hoping that you can help me im installing slate on an outdoor patio in a garden apartment in chicago i was hoping that you could give me some helpful hints and can i use moss in between the tiles if i use some of the mortor as grout but dont go as high as the top of the tile? just create a valley and then add the moss? what about creating a depression in the tiles so they lead to the drain what would you suggest?

There will be a signigicant height difference between my existing curved slate floor and ajoining new wood floors. What is the best thing to use to transition between the two as to not create a "stumbling block"? Please note that 2 feet of the slate is curved.

we are going to lay a slate tile floor in the dining room. the old floor was a wood floor layed over concrete we ripped up the wood floor but there is lrft over glue that we cannot get up. should we use a floor leveler or since its consistant over the whole floor can we just use thinset and then mortar the floor. secondly how do you put the sealer on the floor before you grout do you just use a roller or what??

I have 20 year old tile flooring that is solid with no cracks. Can slate be laid directly over this ? Would rather not do removal.

how do i clean the mold from the gout on a shower stall that is slate tile withou hurting the slate itself?

You wrote slate "can be tough to clean" referring to shower walls and later wrote slate "is very easy to clean" referring to floors. Would using Rain-X, CLR, or similar make cleaning slate in a shower easier?

As I'm my own contractor for the project, what would be the best option to offset the height difference between a bathroom floor and hallway floor?

I have slate panels on my exterior cement steps which have come loose. Would portland cement be the best way to repair this?

Hello,

We are planning on installing slate on top of our outdoor concrete patio. Will I still need to grout or can I place the tiles (12x12)right next to each as is done with marble or travertine?

Thanks,
Juan

We acquired a bunch of old roofing slate, I'd love to use it as flooring in our sun room. Could it work?

My shower floor is slate over a cement raised base. Does slate allow water to seep through the soft slate flooring? Does the base need to be prepped with a substance to prevent water from leaking through? We have a water leak ,that appears to be in an area where water settles.

I just converted a small, old horse shed into a cabin. Would slate be OK to use both as flooring (over sub-floor) and on the lower interior walls(made of plywood), in Michigan, where the temperature can drop below zero? The cabin is not typically occupied in winter and so the heat is not always on. Is slate also flame-resistant (can it be safely used as walling around the wood-burning stove)? What about using slate outdoors on verticle surfaces (such as for the "skirting" of cabin)? I recently tiled my mother's bathroom with ceramic tile and it wasn't too hard - would slate be much harder? I can't decide between slate or a wooden floor! Thanks SO much.

Can you use slate over radiant heat floors? If so are there any changes in installation as far as grout or mortar to use.

Dear Tim,

I have an existing concrete stoop in good condition I would like to overlay in slate, all pieces are 1/2 inch thick. Can you please advise me with a detailed list of steps I would need to follow for proper installation? Thanks a bunch.

I want to install 12"x12"x1/2" slate in my laundry room. we have 3/4" hard wood in the room that is next to it. Will a 1/4" cement board instead of the recomended 1/2" be okay? If I use 1/2" I will be higher than the hardwood and worried that it would be a trip hazard.

My slate is for a cabin that endures some very cold winters. If I use the slate tile as outside skirting for the cabin, do I use thinset or another type of adhesive (for outdoor adhesion)? Also, what kind of grout is good for outdoors, or do I even need it? Also, I spaced 16 x 16" floor slate tiles about 1/2" apart (because I read that the further tiles are spaced apart, the more rustic they look), without first using sealing grout. Will that be a problem? This is a first time job! Thanks

Hi I recently received some damaged "bad" slate tile 12"x12". We are wanting to put it on the basement floor of a bathroom rehab. There is not a sq piece in the bunch. My questions are

1. How do you know when a tile is too damaged and can they rust?
2. Can the sharp edges on the tops of the tiles be sanded or softened somehow?
3. Is there a way to fix tile that is flaking?

We are planning on getting a wet saw and making squares and rectangles out of the pieces. We are trying to stay green and salvage this tile. All the help you can give would be greatly appreciated.

I am having difficulty finding info regarding installing slate tile OUTDOORS - should I use a different adhesive, grout, and sealer than I would indoors? It is for a vertical and horizonatal surface. THank you!

A professional installer installed slate flooring for me. A few people said it does not look like it's been sealed and has a lot of dust on it. How can I tell if my slate flooring has been properly sealed?

Do I install outdoor (vertical) slate tile the same way as one does interior slate? Thanks!

I have a 1/2 plywood sub floor in the kitchen. Can I add 3/4 tongue grove plywood over top and then install crack isolation fabric and then the slate floor?

Thank you for your time.

How can I install slate tile to a surface OUTDOORS ?

We are installing slate as the mantel and hearth at our fireplace. We decided to also use slate on our stairs. Would that be a problem? And do you have any suggestions on how we should finish the edge of the steps?
Thanks so much!!

hi, iv'e been asked to seal a kitchen slate floor, the floor has been laid and grouted but they said they didnt seal it,would i have to clean floor with anything special! how long do i need to leave the floor untouched!if i clean it+after i have sealed it, if you could help i would be most appriciated
thanks NIK

I'm installing 12" x 12" slate tiles on an octagonal floor. I've read that I should lay out the entire room, starting at the middle, including cutting the pieces around the edges, before setting in the thinset. We are going to use spacers. My question is: once the entire room is laid out, then what? do I pick them all up and try to remember which tile goes where? Do I then start in a corner or at the far wall and work toward the door?

Also, some people have recommended sealing each tile individually before grouting to prevent sealer from dripping onto the edges of the tile or else the grout won't stick. Your opinion on that?

Thanks!!!!!

Can slate tiles be installed on 5/8 inch OSB instead of plywood?

I have layed slate concrete floor, and because of the nature of the Riven slate, there are lips and raised edges all over the floor, rather unatractive.
Is there any way of getting rid of the raised edges/lips - making the stone slightly smoother, edges more even?

we had slate flooring installed in our new house. the problem is its about a 1/4" higher then the rest of the floor. we dont realy like the look. we have 3/4" toung and grove plywood sub floor. What can we do to fix this problem and is there a building code for this in minnesota? Troy Palmer

Do you have a video showing how to layout mesh backed slate, I have seen mesh backed slate in 5 and 7 peices, the ones I am using are 7 pc. Any good advice for what to expect the yield to be, my space is small, 5 x 10 ft. and the local supplier gets $ 5 per ft. retail. It seems like quite a bit of waste.Thanks, edgar

We are planning on laying a new slate tile floor in our kitchen. The old 1955 tile currently on the floor are asbestos and we were told to tile directly over top of those and not try to remove them. What is your advice with respect to this? Can we just lay the adhesive directly on the old asbestos tiles and place the new slate tile on top..then proceed to grout as usual?

We need clarification on subfloor for slate. we are a new construction installing 16X16X1/2" slate. We have 3/4"OSB subfloor - do you suggest an additional 1/2" plywood plus cement board or can we do a 1/4" hardibacker directly on the subfloor?

While redoing steps on my front porch I found two big piles of slate that looks like it was from an old slate roof. Do think this can be cut into rectangles or squares and used as a flooring? I say cut because many of the edges are thin and sharp.

Hi ATB,

We just finished grouting the slate tiles in our shower (walls, ceiling and floor). It looks absolutely stunning. However, I think we allowed the grout to dry for too long, and noticed some excess grout on some of the tiles which was virtually impossible to remove. We sealed the tiles prior to grouting, but is there a way to remove the "dry excess" before we seal again? Please help!! Thank you!

ATB, 2/22/09
We just installed 16x16/720 sq ft of Black Brazilian Polished slate. the oil based sealant we were advised for our matte/natural finish was applied.
The result is a wet/highly relfective finish WE DID NOT NEED. It does not even come close to the natural finish in the kitchen. Is there a process to strip or reduce the shine to the natural finish. Seeking expert advice...Thank you.
J.T.

We are about to install beautiful slate tiles in our remodeled kitchen. The slate is very natural and the cuts for each tile are rough-meaning not a smooth top but a more jagged, natural,rough look. We want to use toe kicks around the cabinets but are looking for any solutions or suggestions on how to achieve as little gap (or no gap) as possible between the slate and the toe kick. Is this possible? Thanks for you reply.

What would you do different if the slate is to be installed outside in MA, near a pool? What kind of thinset? fabric?

You mention to seal. I am looking at slate from American Slate Co and they say no sealing is required for their slate due to the depth from which it is quarried and age. Any thoughts on this? I am looking to have a little over 600 sq feet installed. Laundry, powder room and kitchen.

I am restoring a farm house built in the 1840s. The kitchen/dining room has a very large stone fireplace and exposed large oak beams. There is a Carriage House on the property that has a slate roof that needs to be replaced. I would like to recycle the slate. Would I be able to use the slate from the roof on the kitchen/dining room floor? What planning considerations would be required?

Hi, I have slate pieces, tons of uneven sizes (all the same thickness), I am wondering how I use them for floor tiles??

Two questions on installing slate tile. Can slate be laid over sheet vinyl flooring that is well glued to the subfloor? Can you explain "rectified tile" installation (no spaces or grout lines show)?

We were wanting to install slate on top of our concrete enclosed patio! Would this be a good ideal? The patio sits on a concrete block foundation and it may still be expossed to climate changes.We live in southern Ill.

I'm installing slate on my concrete porch and there is an adge to go over, with a row of vertical trim to install below it. Since slate doen't come in bullnose pieces, what is the best way to handle the egde?

Hi there,

I am considering using slate tiles on the kitchen floor of our new house. The current floor is hardwood that was distroyed by the previous owners with floor paint and burns. Can I put the slate directly on top of this floor? Does the harwood need to be removed first? I am not concerned about a small floor height difference in the doorway out of the kitchen if installing the slate on top of the harwood is acceptable. Thanks!~

Our landlady had slate floor put in our rental house. It has uneven edges sticking up, and our feet are black walking on it. How can we remedy the stuff coming off on our feet? Thanks!!

Hi ATB,
I am considering installing slate in my bathroom. I am not fond of the "squareness" of the tile and was wondering if I could have it layed in a European Fan design. Is cutting the tile into the various sizes a bad idea (labor intensive) or is it not recommended for slate?Thank you.

As far as putting slate in showers- is there a particular sealer that will help making the cleaning process easier? Also, are slate slabs going to be too heavy to put on the walls of a shower? Thanks!

im using old roof slate on my floor ive tryed this before on a floor in a gift shop and some slate broke loose this time in my kitchen how can i be sure this wont happen again

Lisa

I installed slate in my basement in the bathroom and bar area. I noticed that there was some excess grout on the slate that I need to get off prior to sealing it. It has been about 3 days since we laid the grout and it is a little difficult to get off of the slate. Any recommendations for taking it off? Thanks.

I am building a new home and would love to install slate flooring in the living room and the adjoining open concept kitchen. I will be installing an in floor heating system in a concrete slab. Any problems with this or tips on how the whole system should be done.
Thank you
Ken

We have slate in our kitchen floor; I love the look but the kitchen chairs don't slide very well. It's not a big deal with just ourselves but guests don't seem to grasp the concept that that can't slide the chair back while they're still sitting on it and I'm scared that one day someone will break one of my dining room chairs. Do you have any suggestions? (I feel like I'm nagging every time I have to remind someone not to try to slide)

We had 12x12 slate tiles installed in our shower and bathroom floor. We did 2x2 slate tiles on our countertops. You should diffiently seal before grouting! If you don't it is going to be very difficult to clean out all the grout from the "pits" that are characteristic of slate. We used a grey grout that basically blends in with the tile. Just know that your tiles are going to be uneven due to the thickness of slate.