Tuesday, August 28, 2012

Installing a slate tile floor

For the present project that we are working on Vermont slate tile was chosen for the mudroom entry way as well as the half bathroom that is attached to it.

Now this slate comes in an assortment of sizes so laying out the floor isn't as easy as you would get in a standard tile floor. There really is no pattern and the trick is to vary the sizes and to make sure you break the lines so it keeps the random look.

But let's start at the beginning of the process. We were going to be using Ditra  by Schluter for the layer in between the subfloor and the tile and, to be honest, I have only installed this type of slate once before and it was a long time ago- long before Ditra was around. With that in mind I decided it might be a good idea to see what Schluter had to say on the topic and I'm glad I did. Because slate is a natural stone product it is not as strong as certain other tiles, Schluter said that we needed to add another layer of plywood before we proceeded and so a new layer of 3/8" plywood was added to the 3/4" layer. Once that was done we could proceed.

As you can see the new layer has been attached and now for the layer of thin-set. 
Now for a very important point. This layer of thinset, below the Ditra, can be a Latex P.C mortar but you cannot use this on the layer between the Ditra and the tile or slate. For that layer of thin-set, it must be an unmodified thin-set mortar. Here's the reason- the latex thin-set when sandwiched between the plastic of the Ditra and the above tile may take days or may never dry because there is isn't enough absorption or air flow to cure it.
As you can see we have avoided two potentially huge problems by making sure that we followed the manufacturer's recommendations.

We had already laid out and cut the pieces of Ditra to length and once the thin-set had been applied we adhered the Ditra as you can see below



We are now ready to start laying the slate.


We decided that we would start at the most visible area which was by the entry and entrance into the kitchen. Laying this type of slate is tricky because it's so easy to get into the habit of not looking for lines developing in many directions. As you go along a line develops and then you have to choose what tile pieces to add to break it. It's very much like doing a puzzle but you are making it.



The next step of course is the grout or is it?

Potential problem number three. Slate is a natural stone and you have to seal it before you grout. The sealer is applied and then left to dry for 12 hours. This way, after you apply the grout, it will be easier to clean off the slate and won't stain them.


Slate is not a perfectly flat, smooth surface so cleaning off the grout from the cracks, crevices and irregularities can be a bit of work and even after will require a few additional washings before the finish sealer is applied.

Yet when it is finished, it provides a unique and durable floor.


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