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Feb 11, 2012 12:19 PM

Granite countertop using floor tiles - friea I'm looking at you!!

Inspired by this post:

For over a year I've been musing about installing granite floor tiles on top of an existing arborite counter-top. I've considered gluing and screwing plywood, one layer, over the existing arborite, and topping it with granite floor tiles. You've also used a Ditra mat, which I hadn't known about. Since, I am very impressed with the quality of your research and knowledge, and I would like your honest opinion.

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  1. I do know a few things about natural stone tiles - we redid our master bath last year from scratch including a full gut demo (fun!). Here are a few shots of the finished product, with linear drain. It was a lot of work but really worth it.

    A really KEY thing to natural stone tile installations is ensuring AT LEAST a minimum of 1/720 deflection for the base. What does that really mean? The surface must basically have NO GIVE AT ALL. If the substrate under natural stone tiles moves - at all - you will end up with cracked tiles (or merely cracked grout - if you are very lucky). Ok ok ... we all know that - in theory - no one will ever be WALKING on the countertop, right? But ... might they sometimes hop up and sit on it ... or lean up against it ...??? If there's any give ... cracked tiles! So ... you might get away with less than that but ... I would recommend against it. So ... one thing to keep in mind from a design stanpoint is there will probably be no overhang at all (or a very slight one at most).

    The minimum recommended underlayment is dual plywood (at least 3/4 + 1/2, but dual 3/4 preferred)I also wasn't able to do dual layers of plywood (minimum recommended underlayment is 3/4" + 1/2" (dual 3/4 is even better). What did I do? I didn't have the extra room for that. So I sistered EVERY joist - AND - installed vertical supports every 3-3.5 feet under those joists. So I achieved about 1/1400 deflection but technically "broke a rule" with only one layer of plywood.

    A bunch of companies make these. Schluter makes Ditra. Other good companies that make membranes are Wedi, Noble and Mapei. These are very popular with floor tile installations, and not exclusively natural stone but also ceramic etc.

    Ditra's function is a "decoupling" layer. Most other companies that produce something similar call it "crack isolation". Ok ... so what's it for? To make sure that ANY minor shifts or cracking (< 1/8") that happens BELOW the membrane isn't allowed to be transferred through the membrane - and then into the thinset on top of the membrane. Because ... if the thinset on top cracks ... you will almost certainly get a cracked tile there as well.

    FYI, I have used Wedi and Noble for my installation, as well as stuff by Laticrete. Laticrete makes good waterproofing but I would NOT recommend them for anti-fracture. Ditra is very well regarded but more expensive and requires unmodified thinset. I prefer being able to use modified thinset. So, with that I prefer Wedi or Mapei probably because I can easily buy it by the linear foot off a roll at the Tile Gallery. I don't need to buy a whole roll or a small roll and have waste left over. And ... both are reasonably priced. fyi - Ditra requires unmodified thinset but I prefer modified thinset so I'd rather have that flexibility.

    Anyway ... that is my 2 cents for tonight. No matter what I highly recommend a membrane. It's not a lot of money and it's function is important.

    4 Replies
    1. re: jkling17

      AT LEAST a minimum of 1/720 deflection I'll assume here that you hit the "7" key by accident, But if you didn't 0.00138888888888889" movement won't crack your tile
      So I achieved about 1/1400 deflection How did you come up with that rate of deflection? what did you place on it? How did you measure it?
      I'd realy like to know
      What brand of Koolaid are you drinking?

      1. re: Dave5440

        Sorry that should say L/720. Not 1/720. Most homes are built to a standard of L/360 (joist spacing and height w/ one 3/4 plywood layer. If you put natural stone tile over that, without first reinforcing it accordingly ... cracked tiles.

        It isn't quite so easy to calculate deflection on top of a bunch of base cabinets that are themselves on top of a floor. Floor deflection is very easy to calculate using Deflecto That tool is how I figured out that my floor was at least L/1400 or better - BECAUSE I added all the vertical supports. The sistered joists alone MIGHT have done the trick but there was no way that I wasn't going to go the extra mile since I could.

        Again ... no one is supposed to be standing on the counter ... but people have been known to sit on them or lean against them ...

        The second layer of plywood helps reduce deflection BETWEEN joists (or in this case the supporting sides of the base cabinets. Since the cabinets are probably no wider than 36", that really helps - those become the vertical supports. But then the space "between the joists" is 36" or 24" instead of 16" or less. So the extra plywood is really essential to keep the surface from having any give.

        1. re: jkling17

          Well that does make more sence now, my mistake!

      2. re: jkling17

        Tnx Jeff
        Gotcha - 2 years ago, I installed porcelain floor tiles on the main floor kitchen, front door entrance-way and 1/2 bath and laundry. I removed the glued-on linoleum with a hammer and chisel - lots of fun - then screwed the existing 3/4 plywood into the floor joists. On top I added 1/2 inch plywood screwing in with about 6 to 8 inch separation between screws. I added a further 1/2 inch underneath the washer and dryer. All is solid. No broken tiles and grout is in good shape.

      3. We laid limestone tiles over a plywood base and they did just fine. However, when we sold the house the realtor said having solid limestone could have increased the value of the house....we have solid granite in our new house and I much prefer it to the tiles. I think it all comes down to what you can afford.

        2 Replies
        1. re: escondido123

          No question about it. Seams, at least in my opinion, are not the prefered countertop if you can afford a solid piece. My brother-in-laws house was built new with granite floor tile countertops. It beats plastic laminate for close to the same price, depending on how extensive you go with the installination and if you have it done or DIY.

          1. re: mikie

            Yes mikie, escondido

            This is a DIY low budget - upgrading rather than a new kitchen.

        2. Well, Rosetown, it all depends on what you are going for with respect to floor tiles as an alternate to a solid surface. And I'm not going to get too technical on you because quite frankly, I know the basics and what counts. Coefficients of whatever are great to know, but the practicality of what I did is what counts most to me. So here goes!
          First of all, I would be most comfortable putting the tiles on a double glued and screwed plywood base instead of a plywood put on top of the arborite. Its because the expansion and contraction of arborite compared to plywood is different, and that difference introduces a fair amount of stress between the two materials. This will be transferred to the tiles so you may have issues with tiles cracking and breaking. All materials react to different temperatures and humidity, and this is something to consider. SO I would replace the arborite with plywood and go from there.
          Second of all, there are many reasons for using granite floor tiles. For us, it was the weight and size of granite required for our particular island. Tile on a countertop isn't ideal, but a larger floor tile means minimal grout lines and a nice flat squares to work on. And if you do sell, it is only one factor that people look at. Many many MANY houses get sold with old kitchens needing total redo's, bathrooms that are harvest gold, fireplaces than need replacing. I wouldn't remodel based on that. If you sell, you'll find the right buyer regardless, because who knows? Your buyer may hate that new solid surface arborite you just installed (we hated this in the home when we bought it!), or they may not like the color of your granite, or may be disappointed with the Silestone. I've seen some pretty horrible results when people choose solid marble for example, and get nothing but staining. Or with concrete that breaks and cracks. Its written off as "patina' LOL but in my books, you need to pick what works well for you and what you like. You're living there -- to heck with what others say!
          Third, Ditra Mat is essential IMHO. Not only is a waterproof surface protecting the plywood (important around the sink), it provides some "flexibility". What I mean is this -- when you do tiles on a floor, you usually put a mesh or something on the floor which gives some flex. That means that with minor floor movement and so on, the mesh provides enough "give" so that the grout or the tile won't break. Instead of mesh, you can use Ditra Mat. It has the same effect. We used this on the floor upstairs in the Master Bathroom and have yet to see a crack. Now, this flex is important with countertops, too, because the floor will move as will the joists with variation in temperature and humidity and walking and so on. This floor movement transfers to the cabinets and therefore to the countertop. So any small "flex" that you can build into your countertop will prevent the grout and tiles from cracking due to movement. You need to be aware that you may still get cracked tiles, especially around the sink, IF your cuts in your tiles are fairly square. A square cut will concentrate stresses and it is easier for tiles to break over time simply as a result of this fact. It isn't a huge deal if you've used Ditra mat because remember, the Ditra provides a waterproof surface over the plywood, so any minor water seepage won't affect the structure. It might cause the tile to loosen (but I doubt it) over time, and that can be dealt with more easily than rotten plywood. We have a tiny, invisibletoeveryonebutme crack right by the sink but I'm not fussed. Ditra mat will protect the plywood, and its because we have a 13 foot long island so some flex of the countertop is inevitable, Plus the crack is formed at the edge of a square cut of a tile (thus concentrating all the stresses) that has a very small piece that forms the "L" of the tile (makes no sense I'm sure but I can't describe it further LOL). No one can see it, and it doesn't affect our day, so we don't sweat the small stuff!!
          Here's a link to a picture of the Schluter-Jolly system, which is a nice edging system for countertop tiles. As you can see, they've use floor tiles and slate in their project and it looks quite nice. I would definitely pair the Ditra mat with the Schluter-Jolly edging system and it lets you have nice rounded finished corners -- no raw, sharp tile edges to contend with -- and looks really nice, IMHO.

          Now, the reason I specifically mention Ditra mat is because the Schluter-Jolly system is designed specifically to be used in conjunction with Ditra mat. You'll see this in the install instructions -- the Schluter-Jolly "rails" are of a certain height and you want the tile to be flush with the top of the rail for a smooth finish. You only get this if you use tiles of a certain thickness over top of Ditra mat which itself has a certain thickness. If you use another mat, it may be thinner or thicker, meaning that you won't have the top of the tile flush with the edge of the rails. And you can't compensate for that well with mortar. Not if you want a very smooth flat surface. I'm sure that's confusing but if you check out the install instructions for the Schluter-Jolly system you'll see what I mean.
          In any event, I personally think that what you have in mind would be a super option, but only if you replace the arborite with plywood. It isn't too terribly expensive to do so, and I think you would have a great result.
          Don't be put off by people who feel that only a solid surface is appropriate. If you click on my name and go to my pictures, I'm really happy with the results. I would suggest that a great tile job can look much better than a crap granite or solid surface installation or selection. One of our friends has the latter, and he regrets the $8k he spent on solid surfacing.
          And keep in mind that I do 95 percent of our cooking from scratch including breads. I treat my countertops well but I don't baby them. And the small, fine grout seams have never been an issue. Because it doesn't cost much doesn't mean that it is "inferior" -- when you look at the pictures of my kitchen, you'll see that nothing was outrageously expensive (Ikea cabinetry, tiled countertops, all the sinks and faucets were bought off of Ebay, the fridge and ovens were the previous year's floor models, there's a tiny ding on the fridge meaning a 40 percent discount, the flooring is industrial grade resilient butt-joined Armstrong tiles...) It doesn't have to cost a fortune to look good nor function perfectly. Its HOW you do it. And thinking outside of the traditional kitchen design mentality can lead to wonderful things, IMHO.
          I know you'll have a great result!
          Hope this helps!

          4 Replies
          1. re: freia

            The aesthetics of solid surface vs broken surface doesn't influence me. In a previous home, I had a ceramic counter-top with tiny squares - it was beautiful aesthetically, and functional, except when baking - think flour - difficult to clean. It would be considered dated today but I miss it, and sadly, it's in my past.

            I'm a slow thinker, so I will have more questions. :D

            1. re: rosetown

              Any time, hon. It took me ages to figure out what I was doing and what had to be done for our countertop. Our contractor told us he would install the tile, then jammed out at the last minute. I had to scramble, research, and install the countertops myself. Plus the edging system. Plus the backsplash tile which goes onto the ceiling in coffee area. Had to source and figure out the mortar system, the Ditra mat, its installation, how to cut the huge tiles, the grout, the whole 9 yards. My first attempt at any of this, and I can assure you, the more planning and thinking and research and asking you do, the better off you'll be. And if I can do this, you can too!

              1. re: rosetown

                There is certianly nothing wrong with tiles as a counter surface. I had marble tiles on a vanity top for many years, it too was a low budget DIY project. As such I put down a 3/4" plywood and a 1/2" cement board then went straight to tile. The marble was tumbled so there were no sharp corners and I edged it with more marble. Drop in sink and it was in for 15 years with no ill effects. It's just that one continous surface does have some advantages.

              2. re: freia

                We also used Schluter strips - to edge our travertine shower. They provide a very nice clean finish to the edge, come in a large variety of finishes, and are IMO reasonably priced. Please be aware that even Schluter dealers will only carry a sub-section of the total line of what is available. I'm a big fan of this stuff. For example, I needed 1/2" strips in brushed nickel and but the only thing the dealers carried in 1/2" was chrome. So don't be surprised if you need to special order what you need through the dealer to Schluter (upstate NY). It's totally not a big deal and they handle these really quickly, with only like a $25 shipping fee.

                Again, Ditra is great stuff. I have nothing against it - it was just merely not really a good fit for our master bath at that time vs. other membranes. All the membranes are waterproof.

                Two other recommendations, if you might go with a tile counter:
                1. Epoxy grout. It's pretty much totally waterproof and is highly stain resistant.
                2. Get a really really good stone sealer. Personally, I wouldn't use anything other than Aquamix. Local dealers usually have it for like $50 a quart but you CAN get much better deals online. I once saw a gallon available for only $55. IMO this is the best stuff available. If you don't wish to change the look of the stone, then get a pure sealant, as opposed to an enhancing sealer. If you wish to know what a stone will look like when enhanced, just wet it down with a damp cloth or paper towel.