Ditra vs ProvaFlex

Ditra vs ProvaFlex

That’s right, I said typed it! Bring it on :guedo:

In the last month or so there has been a lot of hype about Loxscreen’s new polypropylene tile underlayment membrane. That’s just a big phrase for plastic tile underlayment. It is being marketed as a replacement product for Schluter Ditra.

Since I use Schluter Ditra almost exclusively as my preferred underlayment for floor tile I felt it would be a good idea to give this stuff a try. I did not do this in order to find a replacement for Ditra, I’m extremely happy with Ditra. I do feel, however, that due to the way this product is being ‘marketed’ to consumers and since it claims to be a replacement for a product I regularly use, people may want a professional opinion about the way it performs. AND! if there is something better out there – I want it.

There is also another very good reason I decided to do this: there happens to be one person all over the internet claiming this product to be better than a silk jockstrap. I’ll save that rant for the end of this post but suffice it to say that, at the very least, I vehemently disagree with his marketing tactics. If you would prefer to start with that rant please feel free to scroll to the end.

I will attempt to be as unbiased as I can as a firm believer in Ditra and the mechanical way in which it works. So to understand the key points of this comparison we should first begin with a basic understanding of that. I will just give an overview of a couple of key parts but you can read the official line from Schluter Here.

Tile being installed over Ditra

Tile being installed over Ditra

Schluter Ditra is a polyethylene membrane with square dovetailed cavities and an anchoring fleece laminated to the underside. The Ditra is attached to your flooring substrate by embedding the anchoring fleece in thinset (modified or unmodified depending on the substrate to which you are installing it). The dovetailed cavities on top are then filled with unmodified thinset and thinset is combed over the top and your tile is installed to it. The photo to the right shows the tile being installed.

The key component  is the dovetailed cavity of the Ditra. See, the thinset does not actually adhere to the polyethylene (which, for purposes of not confusing anyone, and you know, not sounding like an uppity bastard, I will hereafter refer to as the ‘orange plastic’) This is completely normal and in no way compromises the installation – it is normal and on purpose.

Ditra utilizes a mechanical fastening rather than a chemical one. Thinset ‘sticking’ to the orange plastic would be a chemical bond to the plastic. Filling the dovetailed ‘waffles’ forms a mechanical bond by locking the thinset into the cavity.

Cross-section view of Ditra's dovetailed cavities

Cross-section view of Ditra’s dovetailed cavities

The photo to the right is a cross-section view of Ditra. You can see how the cavities are angled back from the top opening of the cavity. The cavity gets wider as it gets deeper – that is the ‘dovetail’. After this is filled with thinset and the thinset cures it is nearly impossible to pull the thinset out of this cavity – it will not move, it’s locked in there. That is what I mean when I refer to a ‘mechanical’ bond.

A mechanical bond is the main reason I use Ditra. This will allow the ‘micro-movements’ in the substructure without transferring them through to the tile installation. The entire tile installation becomes one large monolithic structure which is able to move independently of the substrate. This means that the joists below your floor, or the concrete, can expand, contract and shift with the small movements inherent to structures without compromising the tile installation.

Or, more specifically and simply, when winter hits and your joists expand a little bit your tile and grout will not crack.  Get it? Now I’m not talking typing about a major movement like a bulldozer crashing into the side of your house because  I someone was doing roadwork while intoxicated. I mean the normal movements of any structure under seasonal changes.

That is basically how and why Ditra works. ProvaFlex, according to all the marketing and hype, is supposed to do the same thing. In fact if you read through all their (online) literature (yes, I have) it is nearly identical to everything Schluter has published about Ditra. So let’s start with the similarities.

Both products are marketed as an uncoupling membrane (this is what I’ve described above – the independent movements).

Both are marketed as having waterproofing ability when coupled with the respective band or tape for the seams. However, ProvaFlex is not recommended for use outside of a covered structure – you’re not supposed to use it on your porch.

Bottom of ProvaFlex next to bottom of Ditra

Bottom of ProvaFlex next to bottom of Ditra

Both are marketed as having vapor management properties. This is a method of equalizing or dissipating vapor through the open channels beneath the membrane to prevent moisture build-up below your substrate. Confused? Nevermind, then, for the sake of argument let’s just assume that they both do that.

Both have an anchoring fleece laminated to the underside. The anchoring fleece is what is set into the mortar on the substrate to attach the membrane. They appear identical to me, and are identically difficult to pull off of the plastic membrane itself. I didn’t put a scale on it to gauge the difficulty, but it seems nearly identical to me – so let’s go with that. They’re the same.

Both are a form of plastic. Ditra is polyethylene and ProvaFlex is, well, I’m not really sure what ProvaFlex is. The online literature states it is polyethylene as well but the written literature included with the product states “Polypropylene material – Impermeable against other building chemicals. Easier to install and lays out flatter than polyethylene.” I do know that it did indeed seem to lay out a bit flatter than Ditra but that may be due to the smaller cavities in the top or the type of material – I can’t say which for certain. Someone apparently has their wires crossed somewhere and it is my opinion that it is the available information online because, well, why in the hell would you send erroneous information with the actual product? But, I really don’t know. There will be more about this in my rant. :D

So it would seem that both products are marketed with identical benefits. But we all know that without actual hands-on use I could market a baseball bat as an environmentally friendly hammer – doesn’t make it true. So let’s move on to the differences.

Top of ProvaFlex

Top of ProvaFlex

The ProvaFlex has an overlaying mesh or webbing attached to the top of it. I like this. It just seems like it would add more of a mechanical fastening to the membrane and stiffen up the installation itself. Whether that is actually true or not – I have no idea, but I still like the fact that it is there.

ProvaFlex with overlaying mesh removed

ProvaFlex with overlaying mesh removed

When I peeled this webbing off, however, I was a bit disappointed in how easily it was peeled back. I expected it to be nearly as difficult to remove as the fleece on the underside – it was not. It is attached fairly well but not nearly as well as I would have liked or been comfortable with. Maybe I’m just an anal bastard a demanding consumer – I don’t know. I still like it, though.

Ditra’s surface is comprised of 3/4″ square ‘waffles’. ProvaFlex’s surface is comprised of alternating 3/4″ circles and 7/8″ ‘flared’ squares – or whatever the hell you wanna call that shape, with raised circles in the center. Shape-wise (is that even a word?) I don’t think it makes much of a difference but I can’t say for sure one has the advantage over the other so I’m callin’ that a wash. I will say type that the ‘pillars’ created by the Ditra will have a bigger, more consistent footprint in contact with the substrate.

The thickness of both products seem identical but if you slam a micrometer on them I would guess the Ditra is just a platypus hair thicker. (A platypus hair is really thin, by the way. Don’t ask me how I know that, let’s just say it involved a midget and a case of scotch…or so I’ve heard  :whistle: )

So this far I would call it fairly even as far as a practical application indoors. If you don’t agree, well, start your own damn blog. I’m callin’ it even – up to this point. There is one major difference that is almost certainly a deal-breaker for me – the ProvaFlex cavities are not dovetailed.

The online literature and marketing hype – all of which compares it as an alternative for Ditra at a lower price – states, and my computer quotes “…with a grid structure of square, cut-back cavities…” Just a bit (ridiculously) misleading if you ask me. The shape of the cavities is most certainly not square and if by ‘cut-back’ they mean dovetailed – they most certainly are not that either.

This may or may not be a marketing ploy – it is not for me to say (yet) but the description can ‘technically’ be described as accurate if by ‘cut-back’ they mean the shape of the funny looking squares and by ‘square’ they mean the shape of the cavities in the z-axis, as it gets deeper.

Physical literature included with ProvaFlex

Physical literature included with ProvaFlex

This, however, only seems to be on the online marketing sites. The physical literature included with the product itself specifically states “Square Cut Adhesive Cavity” pointing to a square (not dovetailed) cavity on the surface of the membrane. It does not seem to me that the Loxscreen company, the manufacturer of ProvaFlex, is attempting to pull the wool over anyone’s eyes as far as comparing it as an identical product in form and function. Not as far as the mechanical bonding process, anyway. It appears to only be the online marketing.

Cross-section views of ProvaFlex and Ditra

Cross-section views of ProvaFlex and Ditra

The photo to the right shows the cross-view of both products right next to one another. If you click on it and ignore my shitty photography skills you can plainly see the dovetails in the Ditra (top) and the square (or slightly rounded) cavities in the ProvaFlex (bottom).

If you can envision filling the cavities of each product with thinset and allowing it to cure then pulling straight up on each, what’s gonna happen? Without the mesh or webbing on the ProvaFlex that little fill of thinset will pull straight up and out – the Ditra will not, it is locked in due to the dovetail.

I’m no expert or anything (yes I am) but it appears to me that the ProvaFlex’s mechanical bond relies on the mesh or webbing attached to the top of the membrane. The method of the mechanical bond is different.

The bond for the Ditra relies entirely on a mechanical process, the aforementioned dovetails. The bond for the ProvaFlex relies also on a mechanical process, the webbing or mesh attached to the top of the membrane. This webbing, in turn, is attached by means of a chemical process.

I’m unsure what this chemical process actually is. I’m certain it is a trade secret and they would send black helicopters after me if I were to divulge it. I don’t know – I don’t care. It does not change the fact that the bond with ProvaFlex is not truly and entirely mechanical. The entire bond of your tile installation relies on the process and durability of the mesh webbing attached to the face of the ProvaFlex membrane.

So when you decide which product you want to use under your tile installation you should take into account the method of attachment. ProvaFlex seems like a decent product for a small application such as a small bathroom without excessive traffic or maybe a small countertop. It is entirely up to you whether to use it or not.

It will work to an extent and with certain applications. I just did two bathroom floors with it which I now own. That means if this stuff fails I’m paying to replace them, so it better not fail. But with any new product someone has to take that risk. If it does fail I will absolutely let everyone know – believe that.

This product will not be a replacement for Ditra for me. Anywhere I can use ProvaFlex I can use Ditra instead. I don’t believe the reverse to be true. If you install hundreds or thousands of dollars worth of tile do not nickel and dime the price of your underlayment. Saving one or two hundred dollars now may lead to replacing the thousands of dollars worth of everything later on down the road.

I am not saying it will fail – I’m saying I don’t know. With Ditra I know.


This is not a rant against ProvaFlex, it is a rant against particular individuals marketing ProvaFlex on the internet. If you want to know who it is – google it, this jackass is all over the place.

I have no problem with marketing a product. I do have a problem with the method it is gone about. If someone needs to bash another company in order to sell their own (or one they are shilling) it is not only disingenuous, it is absolute bullshit.

The marketing descriptions and literature available online from this particular individual seems to be at complete odds with the product’s own marketing information. That is a big red flag.

This person apparently has had a disagreement or falling out with the Schluter company (as well as a couple of other very large, major companies in the industry) and has taken it upon himself to attempt to discredit everything about them.

Under the guise of ‘Schluter is crap and they screwed me so here’s a better product…’ he attempts to peddle ‘Prova’ products claiming they are better engineered and cheaper than Schluter products. They are cheaper, no question. Better engineered? You be the judge, that’s why I did this.

This guy bashes everything about Schluter, attempts to make false arguments such as ‘thinset doesn’t even adhere to Ditra’ (no shit) then turns right around and copies their marketing literature and substitutes his product in place of Ditra and Kerdi. THIS is where the inconsistency in things such as the polyethylene and polystyrene differences come from. Oops, forgot to change that part – jackass. The “…with a grid structure of square, cut-back cavities…” quote earlier happens to be exactly how Schluter describes Ditra – which is accurate.

The descriptions, methods, and even chemical makeup of the product, is at complete odds with the product’s own literature. Why would that be? I have absolutely nothing against Loxscreen or Prova-flex, hell, I tried it myself. I do take issue with assholes attempting to discredit one product in order to sell another. I believe if Loxscreen wishes to own a decent market share of this industry in the United States they should prevent this asshole from selling their products.

ProvaFlex may indeed be a product inspired by Ditra but it works differently, people need to know that. Attempting to force-feed the idea that it is an identical but cheaper product is bullshit. You are taking advantage of people inexperienced and uneducated about what the product should do for the purpose of profit. Please kindly go throw your own dishonest ass off a large cliff.

Please, please research anything you plan on using for a tile installation. Get more than one opinion – always. Even if that one opinion is mine (which is right, by the way) go get it from someone else. The better educated you are about it the better off you will be.

Now that you know how ProvaFlex works you can make a more informed decision about whether the amount you save is worth it for your particular application. If you want to use it and it sounds like the right product – use it. Just don’t buy it from the asshole.

If you have any questions please feel free to leave a comment. I’ll help if I can. Please understand I’ve only used this product for one installation so all my information is based on that. I have used Ditra (literally) hundreds of times. If you are the particular asshole I’m ranting about – and you know who you are – stop taking advantage of people’s inexperience and feel free to go find the aforementioned cliff.

Rant over. :censored:

{ 428 comments… add one }

Leave a Comment

  • mamaligadoc

    With respect !!!

    • Liz

      Hi the writer of this article seems really clued up on these membranes. I have a question that I am hoping the author maybe able to answer in simple terms. I have had my floor tiled and I noticed on the final day of the tiler working that he had fitted the DURAL DURABASE CI MATTING (approx 60m2) upside down. The tiler said it would do the same job but I am worried it will cause problems. The reason we used it was I have had an extension that has a concrete floor and we were tiling this and the adjoining kitchen that has wooden floor and both have wet underfloor heating installed.

      • Roger

        Hi Liz,

        It may or may not work. It depends on the movement of the floor. The answer to your question as to whether or not it will do the same job – no, it won’t work the same way. The underside of the sheet that normally is bonded to the subfloor is a single plane, as it should be. The top side creates individual pillars of mortar locked into the cavities to allow lateral movement of the installation. Upside down it will do that TO A POINT, but it won’t be the same.

        • Liz


          Thanks for getting back to me. It is really frustrating to hear that. I basically have to wait & see if it fails due to my tiler installing the wrong way. The tiler is being quite dismissive about my concerns & says he will guarantee for a year. (The way he is acting makes me think he may not come back if it fails anyway even in the first year) I would expect a job that has cost me 2.5 thousand in materials and 2.5 thousand in labour to last 10s of years not just 1 so if it fails after a year I will be very disappointed. I get that it seems a shame to rip up newly laid tiles but I have to live with the stress of knowing these might not last & may need ripping up & tiling again in the near future due to my tilers mistake.

  • Mike


    Playing devils advocate here. If you are basing your decision on Ditra being superior to Porva Flex due to the fact Ditra has dove tail squares to mechanically bond the tile to the underlayment what are your thought on Ditra Heat and Ditra Heat duo?? Not getting into all the detail but a heating wire can be run through them while also acting as the underlayment. These do NOT have dovetail squares, rather octagons that are NOT dovetailed. Is this product inferior?!?!?

    • Tony

      The detents in the Ditra heat still create the pillar effect. Same physics still apply when installed to Schluters’ specs. (Flat trowel then come back and use ridged side of trowel. This ensures even coverage, thus building a foundation)

      As you fill mud in around the bottom of the “octagons”, it will lock in like the dovetail in regular Ditra.

      Often imitataded, never duplicated!

      • Mike

        So the same could be said about Prova Flex?

        • Roger

          No, because the little ‘pillars’ in the provaflex are uniform from top to bottom. Take a close-up look of the cross section photo, you’ll see the sides of all the cavities, including the ‘pillars’ are all straight and vertical – no dovetail in either direction.

    • Roger

      Hi Mike,

      Those products are absolutely NOT inferior, and I use them all the time. The pillars on the mat actually are ‘dovetailed’ upside down – the top of the pillar is larger than the bottom of the pillar. This, in effect, creates a dovetail in the mat. The open spaces between the pillars IS dovetailed due to the shape of the pillars.

  • Mark

    I am a Ditra fan and have used it many times. Doing first project in a while and did some online pricing. Found many, seemingly reputable, sites where there are VAST price differences. For example, the range for a 30M roll ranges from almost $700 to $350! The higher end numbers are at the big box stores, the lower end on eBay. Anyone have good or bad experiences to share on this? Clearly I’d rather pay $350 than $700 per roll!

    • Roger

      Hi Mark,

      I’ve actually never ordered it online. I do know that schluter has MAP pricing for all approved dealers, which means you’ll be paying close to the same price everywhere. However, that does not preclude sellers who may be private and have excess stock, etc. I would say just to research the seller you’re thinking about buying from and use a payment processor that gives you online purchase protection like paypal or a reputable credit card company.

      • Mark

        Well I took the leap and ordered online. Two rolls of 30M arrived this week. They appear to be genuine in original packaging, at a savings of almost $600. Hopefully the installation goes as well!

  • Eric

    Does Ditra meet the standard for crack isolation or movement of 1/16”-1/8”?
    Why not just use a crack isolation membrane ?

    • Roger

      Hi Eric,

      Yes it does. If you ONLY need crack isolation, use a crack isolation membrane. Ditra, however, has more advantages than just crack isolation, it works well for vapor mitigation as well as giving the entire lamination isolation capabilities from the entire substructure, as opposed to only a specific area (like crack isolation membrane). It also adds crack isolation to any area that may require it AFTER the tile installation is installed, such as a concrete slab cracking a few years later.

      • Eric

        I searched the schluter web site and no mention of it meeting the ANSI standard for crack isolation or any other standards. Also no mention of how much movement it will handle. How is the vapor mitigation tested?

        • Tony Raftery

          The ANSI listing is in the brochure for each product you purchase, I believe. Long time Schluter user/installer myself. They meet or exceed ANSI listings and can give page references out of the book if needed. (Talk to your local rep)If you have the chance, attend one of the work shops. You will be overwhelmed with info and all the certs they have on their products.

          • Eric

            Yes,please list the ANSI standards for both Crack and Moisture mitigation they meet.

            • Roger

              Eric, We as installers don’t memorize each product’s specifications. Schluter has a customer service number as well as a number for your local schluter representative – give them a call and they’ll be more than happy to give you all the information you need. It’s what they do, it’s not what we do. :)

              • Eric

                I did, they dont have it either. There is no test for uncoupling or moisture mitigation.

              • Tony Raftery

                I agree. I would have to dig out my book(s) and look all that up. Please do contact your local rep. He/she will have all the answers and then some.

                • Eric

                  I did Tony ,they do not meet or have any test data available for crack isolation or Moisture mitigation.

                  • Tony Raftery

                    I not so sure about that. I have heard/and seen the listings for ANSI. I’m not sure what else to say. I was in a Schluter workshop and the listings and test results of moisture/movement were right there in print. I wish you the best on your endeavors!

  • Roger

    Hi Regina,

    A similar system is your best bet. There are now a LOT of uncoupling mats available, some at a significantly lower price point. Most big box stores carry some sort of uncoupling mat, just see what you have available locally. Most are cheaper than schluter.


    I was wondering on the thinset for the Ditra? We are doing our bathroom floor. Do I need to use the Shutler thinset or what do you recommend?

    • Roger

      Hi Angela,

      Any quality unmodified thinset will work fine.

      • Tony Raftery

        Tec makes a good unmodified thinset. Can be found at depot or any floor/tile supply store

  • Jbrady

    What’s your thoughts on the Mapei Mapeguard vs Detra? Looking to install large format tile on a kitchen. Just replaced joists and subfloor with doubled 3/4 on 2×8 16” o/c. Probably 20’x20’?? What’s your thoughts

    • Roger

      Hi J,

      I prefer ditra, but either will work just fine.

  • david loo

    I purchased your shower stall tutorial and am in the process of building a curbless shower (4’6″ x 5′) and am working on the recessed floor at the moment. I plan on constructing a mortar base with Denshield walls and topical waterproofing of the base. My question relates to the Schluter drain. Not being firmly screwed down gives me pause for concern. I note that the ProVa drain may have the capability of being screwed down and additionally seems slimmer (I haven’t actually inspected either drain because they are not retailed in Hawaii so my only references are online photos); have you ever installed a ProVa drain and if so, I would appreciate some feedback as to its pros and cons vs the Kerdi drain.
    BTW, my house is built on post and pier construction, so I will have access to hook up the P trap after the drain is installed so I suppose I can always put in some supports to make sure the drain pipes directly under the shower drain are rigidly anchored and secured. Your installation tutorials are excellent.

    • Roger

      Hi David,

      Both of them are capable of being securely screwed down, but it’s not necessary as both the deck mud around the drain body as well as the bonding to the p-trap below it will anchor it more than enough.

  • Alex - nonexpert

    Re: mechanical bond due to dovetail.

    Isn’t it significant *only* if there would be nothing on top of ditra? What difference does it make once all is compressed by the weight of the top tinset and tile? I’d say – none, just makes you feel better about it. I’d further bet that it would be fairly easy to pull it off anyway if you just put the bottom layer + ditra, wait for it to cure and then pull. I can’t imagine it would fight too much.

    Both seem to solve one issue: decoupling. As you suggested, if one was to mold each side and then separate, the hard (tinset) structure of the bottom and top layer do not directly touch thus preventing direct transfer of mechanical stress from the bottom layer to the top.

    I’d expect that if we could observe the floor done with either, after a few years, cracks would be isolated to the first (bottom) layer, under the ditra since hard and rigid material of the tinset can not take well shear and tension and will tend to crack. However, this tension will not be transferred to to the top tinset layer (and thus tiles) since plastic in between will take all the plastic deformation.

    My 2 cents.

    (I’m mechanical engineer by education)

  • Tony

    Hi, I’m a fellow tile installer and use nothing but Schluter/Kerdi. It has been proven to be superior in my opinion. I’ve installed just about all prep products and you can’t beat Schluter.
    I agree with your opinion as well. Dove tail is the key with Ditra as well as all Ditra/Ditra Heat products. Yes, the price point is higher, but, I inform my customers you basically buying an insurance policy. My warranty on top of Schluters 10yr how can you go wrong?
    Thank you for the reviews. Keep em coming.

  • Robert

    Have you ever tried/reviewed either of these floor matting products?

    Dural Durabase CI++

    Homelux Floor Matting

    • Roger

      Hi Robert,

      This was posted before those products existed. But yes, I have used them. They all work pretty much the same. Never had, nor heard, of failures when installed properly with any of them.

  • Colette

    Hi, I’m planning to install a whole bathroom including shower in the next couple of weeks.. The house is made of concrete, so would I still need a backerboard to secure the tiles? Thanks

    • Roger

      Hi Colette,


      And yes, I realize this reply is likely too late, but the info will be here for others in the future. Sorry for the delay.

  • Marie Gentry

    I am installing a shower in a old pier and beam house that is 3’ off the ground and frequently shifts. Should I use Ditra under the Schluter shower pan?

    • Roger

      Hi Marie,

      No need to. The foam pan will lend more than enough flexibility to compensate for movement without transferring it up into the tile. You can if you want, but it’s not really needed.

  • Jacque

    Wow! I never even knew something like this exists so bear with me. I chipped off tile off of a concrete floor and am redoing a bathroom floor. The part of the tile I bought is not as think as the rest of the tile I bought so I was looking at how to make the tile be the same height and I read laying strips of ditra will help level. So I started researching ditra. I live in California, lots of earthquakes, and am now wondering if I should lay ditra under the whole floor? And if I do, I still have the issue of different tile depths. Is this a good answer for leveling? Do I do this in two stages? Lay an underlayment over the whole floor and then put an additional layer of Ditra in small pieces to level?

    • Roger

      Hi Jacque,

      Yes, you should install it over the entire floor. If you are speaking of some sort of insert being thinner, yes, you can install more strips of ditra under that.

  • John

    Will “pre-filling” the Ditra voids reduce the bonding when you install the tile the next day, since you will be creating a “cold joint” between the “pillars” of mortar in Ditra and the tile mortar? When pouring concrete, cold joints reduce bonding. The same should apply here, so engineering logic tells me it would be best to fill the voids as you set the tile, not a day earlier. What say you, sir?

    • Roger

      Hi John,

      The crystalline structure of curing thinset is a bit different than regular cement. The only way you could create a cold joint which MIGHT minimally affect the bonding would be if you filled the ditra more than 28 days before setting the tile. However, even at that point with the porosity of the fully cured thinset there would still be significant bond since the growing crystals of the new thinset has more than enough space to grow into.

    • Jeremy Lunning

      No, and it’s actually recommended by Schluter for small tiles according to my rep.

      • Roger

        Jeremy is right, you know. :D Also keep in mind that ‘smaller’ tiles only constitutes tiles 2×2 and larger, the minimum recommended size of tiles over ditra. I prefill all the time.

  • Roy barnes

    Am doing a 1000 SF tile installation. The dealer recommended the ditra system. Your article was very helpful becauseI never heard of Ditra. What should the contractor price to lay tile using the Ditra system in NY be per SF (approximate). Thanks

    • Roger

      Hi Roy,

      I have absolutely no idea at all.

  • Terence Murphy

    My basement floor is concrete and covered with glued down vinyl 1×1 floor tile. I want to replace with a natural stone or tile floor
    What’s the best way to proceed

    • Roger

      Hi Terence,

      The vinyl will have to be removed as well as any paper backing from the vinyl or glue left on the concrete. Scraping it up really is the easiest way – and it isn’t very easy.

  • Robert Desbruslais

    Hi Roger I have just carried out a survey on a huge house with this system under the tiles. Pot and beam floor. House is 5 years old and several tiles are flexing and squeaking a little. Any ideas?

    • Roger

      Hi Robert,

      I would need much more information to ponder an educated guess as to the reason. Do you know the deflection rating of the floor? Type of substrate beneath the prova? Brand and type of thinset?

      • Robert Desbruslais

        Hi Roger. All I know is its a pot and beam floor. It’s a high end building, very high spec, indoor pool etc and good quality workmanship and materials. Vendors are not technical and have little info.

        • Roger

          Well, my first guess would be inadequate coverage of thinset beneath the tile, but you would need to remove a tile to verify this. I would bet that when you remove one from the field (make sure it’s a full tile in the middle somewhere, not a cut tile) that there is little or no thinset on the back, and you may even still see trowel lines ghosted on the back of the tile. This happens for several reasons, number one being not backbuttering the tile, along with spreading too much thinset at a time, not a large enough trowel, and improperly embedding the tile into the thinset. The reason you want to check a full tile is because much of the time on commercial work one crew will come in and do all the full tiles, then the next day either them or a different crew will come in and do the cut tiles, oftentimes applying the thinset to the tiles themselves rather than the substrate. That’s where I would start.

          • Robert Desbruslais

            Excellent I will recommend that further investigation thanks.

  • David Keeney

    I have been told by several contractors and a a Ditra rep you can coat Ditra 100% and then come back the next day and trowel modified thin set over the Ditra with porcelain tile. What is your opinion and will that cover Ditra Warranty. Thank You David Keeney

    • Roger

      Hi David,

      I have absolutely no problem with that method at all. As far as the warranty – I would get that in writing from whichever rep told you that. I don’t believe that you will retain your warranty with that method.

  • Matt

    Hello Roger! I have your shower books and trust your opinion. I have a new project and I was hoping to get your opinion.

    I am confused about how to proceed with preparation of my floor for tile.
    About 150 sf floor to cover in upstairs bathroom with separate toilet area. Construction is ¾ T&G OSB (unknown Exposure Rating) over wood I Beams (I Beams are 12 inches wide (deep?) and seem to be spaced 19.2 inches apart). Longest span within the room is 11 feet – it may run out to 15 feet before there is a wall (support) below. – I know they used adhesive on top of I Beams).

    New tile is wood look porcelain 6 x 36.

    We had a leak (small drip – while gone for a week) and floor got wet. The OSB subfloor is a bit uneven now (and may have been since new). It was mostly covered with carpet except the toilet area and a “landing” area for the tub/shower. – Both of these areas were tile over ½ inch Durock. The Durock was nailed directly on the OSB (no thinset). These two small area have held fine for 16 years (age of house) – but it still seems that installation was incorrect.

    I want to do the floor prep correct as reasonably possible.

    It seems a given that the cement board (all types) have to be bonded to the sub floor. This is 1st area of confusion. I have read (somewhere) not to put thinset on top of OSB – Drock website states to use latex modified thinset or Type I Organic Adhesive. And notes the OSB should be Exposure Rating 1 or better).

    I guess some will say go ahead and thinset cement board to the OSB. If that is the case any thought to covering subfloor with tar paper or rosen paper? – I do not know the OSB exposure rating…

    I was thinking I would cover subfloor with Luan. I like the idea that (a long time) down the road you could remove the floor “cleanly” after the Luan is removed – back to the original subfloor. But now I have read to never use Luan between OSB and cement board… – Is that true?

    I have also seen some 5mm “underlayment board” in the store – is that a consideration for this application?

    Next thought is to use ¼ plywood screwed to the OSB and then thinset/screw ¼ cement board- I would think that would be a very good foundation for the tile. Of note here is that I would rather not have the height build up but I am willing to make that trade-off for a trouble free install.

    I got an opinion to use 1/2″ BC plywood (a min of 3/8- 1/2 is better) over the OSB. ( I seem to be on the questionable side of if my structure is stout enough). Now because build up height is becoming a concern it was suggested to use Ditra or StrataMat or even green skin on top of plywood – to save height over 1/4 backerboard.

    Are one of these ideas a solid path forward? – or please suggest a good sequence for worry free install.

    Thanks in advance for your valuable knowledge and experience. I am OK spending a bit of extra time/money to “do the job right”. I really want to eliminate any possible future problems…

    • Roger

      Hi Matt,

      First of all – everything you’re worried about stems from a misunderstanding. Durock (or any backer board) DOES NOT need to be bonded to the subfloor. Thinset beneath backer is there ONLY to support the entire sheet and fill any voids. It does not need to bond to anything – it’s a filler.

      If durock’s website says to use type 1 organic adhesive – they’re full of shit. About the luan: NEVER, ever install anything with the intent of it being ‘easy’ to remove in the future. Anything I put down I do with the intention of the person ripping it out hating me for eternity.

  • Prakash Mohan Choudhary

    in kolkata, West Bengal, India how we can get the material

    • Roger

      Hello Prakash,

      You should contact the main company’s helpline number, they can tell you where to locate it. Schluter’s number (for US) is 1-888-472-4588

  • Thomas Linehan

    Most excellent post, I’ll buy you a beer or 3. I’m trying to find a waterproofing membrane for a large houseboat,75′ 55’x24′ interior, steel frame with 2xflat joist@ 1′ o.c. with 3/4″ adventeck ply, any thoughts?? Thinking flexible??? Thanks

    • Roger

      Hi Thomas,

      Your best bet for walls would be a liquid waterproofing membrane. They are also a crack suppression membrane, which means they have a bit of give to them if needed. Hydroban would be perfect for that scenario for the vertical walls, and ditra would be ideal for your floors as it won’t transfer substrate movement through to the surface layer.

  • John

    Userper bastards rant. Check it out. From my experience with ditra I have to say that its proof is in the pudding. It just works. My only quarrel is the price. They sure are proud of that sh_t! I haven’t really seen or heard of any other effective fastening systems for tile installation. Well maybe the old mortar bed & mesh. But things have come a long way from that, which I had the pleasure(enormous PITA) of doing once. If you really don’t want your tile to move, screw it to the floor (I’m bullsh___ng). A customer actually suggested that once. I had no rebuttal. I guess it’s nice to see that someone is offering an alternative to ditra. Is it inferior, who knows? But there is a damn good reason why ditra is what everyone uses. It just works.

  • Double D

    Would you use Ditra on top of 3/4 plywood for tiling? Or would you say that one layer of 3/4 is not enough to adequately support the tile?

    Room is 8′ x 11′


    • Roger

      Hi Double D,

      It depends on what particular type of tile I was installing. Porcelain – possibly. Stone, no. It also depends on the deflection rating of your floor, the spacing of your joists, the unsupported span, etc. There is much more to it than simply an 8×11 size. :D

  • Sergiy

    How can i glue Ditra to the linoleum? Can i buy that kind of “glue” at home depot?