When I answer questions on my site I am always telling people to backbutter their tile. It has recently been brought to my attention that normal people (the ones who don’t stand in showers all day) have no idea what that means.
Backbuttering tile simply means spreading a flat layer of thinset onto the back of the tile before installing it on your wall or floor or whatever.
First you have to ‘comb’ the thinset onto the substrate – that means it is spread with the notched side of the trowel leaving little ridges. It should look like that first photo there on the right with the ridges all combed in one direction. This allows any air to escape from beneath your tile more easily.
One of the most frequent questions I get asked is ‘What size and type of trowel should I use for…?’ The proper answer to that is ‘whichever trowel gives you the proper coverage for your particular installation’.
So there really isn’t one perfect answer to that question, a lot of factors are involved. But I’ll try to help you out.
Proper thinset coverage
The first thing you need to know is what constitutes proper coverage.As stated in ANSI A108.5 3.3.2 for installation of tile on floors; “Average uniform contact area shall not be less than 80% except on exterior or shower installations where contact area shall be 95% when no less than three tiles or tile assemblies are removed for inspection. The 80% or 95% coverage shall be sufficiently distributed to give full support to the tile with particular attention to this support under all corners of the tile.”
That title right there is absolutely ripe for me to go off on a sophomoric, mildly humorous rant about the viability of inferior illegal plant use. But I’m not gonna do that. (Okay, maybe later…)
A soft joint, or control joint, is simply one grout line, all the way down the length of your installation, that is filled with colored silicone or caulk rather than grout. The purpose of a soft joint is to allow movement in your installation without cracking tiles or grout. When placed properly it will absorb any ‘normal’ seasonal and structural movements inherent in structures.
There are guidelines that need to be followed for a soft joint to be effective. The TCNA guidelines call for a control joint every 20′ – 25′ in each direction for interior installations and every 8′ – 12′ in each direction for exterior installations. Interior installations which are exposed to direct sunlight also need control joints every 8′ – 12′.
I know there are some people out there (not my regular readers like you!) that read what I write and think to themselves ‘okay, but I’m sure that won’t happen with my installation’. So periodically I’m gonna post things like this that show exactly what happens when things aren’t built correctly. And yes, it will happen to yours, too, if the proper steps aren’t taken. If you care to see more train wrecks you can check out my ‘flawed‘ page wherein I post photos of absolutely horrible tile installations which I’ve torn out and replaced.
See that crack in the tile right there? (The line down the center is not a grout line – it’s a crack. You can click on it for a larger version) That bathroom floor is less than eight months old. It was installed with hardibacker over the subfloor and thinset. At least that part is correct, but that was about it. There was no thinset beneath the hardi and the seams between the sheets were not taped and thinsetted. To a lesser extent the correct screws were not used in the hardi – they committed the cardinal sin of using drywall screws in the backerboard. Yeah. Wrong.
I constantly reiterate the need for a tile installation to be flat. Not necessarily level, but always flat. This is the mark of a true professional and the thing that turns an ‘okay’ installation into a spectacular installation. (Did I just type ‘spectacular? Jesus…) Anyway, the method I use on floor tile to get it flat is fairly simple and ensures that each tile is the exact same height as the tiles surrounding it.
Before I show you that you need to understand, as always, that the substrate preparation is the most important aspect of this. If your tile substrate looks like a skate park you’re never going to get a flat tile installation over the top of it. Your substrate needs to be as flat as you can possibly get it. Take time with your preparation – it makes the rest of the installation run smoothly and gives you a solid foundation.
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.
Now that your floor looks like a can of silly string exploded (figure 8 ) its time to add more layers to it and cover up all your hard work. If you have not yet done all the hard work then your floor doesn’t look like that. Check out How to install WarmWire Part 1. I’ll wait.
Okay, you may want to check out a speed reading class. Just sayin’. My preferred method is Schluter Ditra underlayment installed atop the WarmWire for your tile installation.
The best method of leveling out your floor for your Ditra would be an SLC or Self-Leveling Cement. This product is mixed with water and poured over your WarmWire. When mixed properly (follow the instructions to the letter – really) and poured it will – wait for it – level itself. When cured you will be left with a level, flat floor.
You can actually install your tile directly to this layer if you chose to do so. I do not chose to do so. I prefer to have an additional uncoupling membrane above these layers then my tile. That’s just how I roll.
One of the best upgrades for a bathroom or kitchen tile floor is the use of in-floor heating. There are several different products available to accomplish the coveted ‘warm tootsies when it is forty below’. One of the more popular products (around here, anyway) is the Suntouch WarmWire radiant in-floor heating. That’s just a really long term for wires that heat your floor (and warm your tootsies).
Now that I’ve used the word ‘tootsies’ twice in one paragraph I believe it’s time to move on.
As an ‘official’ reference the manufacturer’s installation guide can be found online in one of those fancy-ass pdf thingies HERE. It contains all sorts of things that you need to be aware of before starting your installation. While this post will walk you through how I do it, your installation may differ in aspects of which you are unaware. You need to read through the manufacturers information as well before you actually install you WarmWire.
This is as close as I’ll ever get to an official disclaimer: Be aware that the methods I use will differ somewhat from the manufacturer’s instructions intended for the do-it-yourselfer. I am a professional tile guy (really – what are you laughing about?) I accept liability with everything I touch in a customer’s home and accept that risk with the methods I choose to utilize. Read the manufacturer’s instructions before installing your WarmWire!
The days of grabbing a three dollar bag of “thinset” and sticking floor tile right to the plywood in a bathroom are long gone (for professionals, anyway). For a proper tile installation you need a proper substrate. One of the most readily available are cement backerboards. These include products such as Hardiebacker, Durock, Fiberboard, wonderboard and a host of others.
When properly installed on your floor it is an ideal tile substrate for a quality and lasting installation. Notice I said typed “properly installed”? Laying them down on the floor and shooting drywall screws through them does not constitute proper installation.
Choose your weapon. I prefer Hardiebacker or Fiberboard. Whichever you choose make sure you get the proper thickness. With rare exception the 1/2″ variety would be the best choice simply because I like to overbuild stuff. With proper floor framing and deflection ratios, though, you can use 1/4″ to minimize height differences. This is not to say that 1/2″ adds significant sturdiness to your floor – it does not.