How To Install Terracotta Tile Floor in Cob House (with Pictures)

by ziggy on September 27, 2011 -- 15 comments -- Follow


The newly tiled (and styled) cob house

We’re finally back in Gobcobatron! The tile floor is done…. for now. (Yea, we still have to seal it with linseed oil, but April and I are waiting until next spring to be 100% certain the floor is dry… we’re not taking any chances.) The difference in the house is dramatic, especially when you combine the look of the terracotta tile with the newly lime plastered walls. I am really liking it.

In this post I’ll provide a simple explanation of how we laid the tile using clay and sand grout and clay adhesive.

Installing Tile on an Earthen Floor

After we laid our base and final layer of the earthen floor (1.5″ and 3/4″ thick each, respectively — I actually could have done just one layer that was about 2″ that would have sufficed), we set about laying the tile. We waited until the final layer of the earthen floor was about 80% dry to do the tiling.

One of the most difficult aspects of doing this tile floor job was the edges — cutting tiles to conform to the shape of the foundation. I scribed the tiles using a ruler with pencil, tracing the wall outline along the tile, and then I drew a straight line across the tile where it would then be broken. (In other cases, I simply took a measurement where the tile would squeeze in, and drew a line across the face of the tile, instead of tracing the wall shape.)

I was most successful breaking the tiles when I first scored them with an old saw and a sharp nail. Next I would put the tile on a wood block, score line on the edge of the block, and quickly striking the tile with a hard rubber mallet (with a wood block between the mallet and tile.) There were more than a few mess ups. Terracotta tile is extremely difficult to accurately break!

Adhering Tiles to the Floor


Smearing the clay adhesive

I used clay to adhere the tile to the earthen floor — straight clay that had been mixed up a bit by hand, fairly wet, but not so wet that it could hold no shape. This I smeared on the floor, applying enough so that the tile could sit flush with its neighbors. This took a while to learn — how much clay to apply to keep a level plane. Of course, the underlying earthen floor was not absolutely perfectly level, so the height of the clay would change along the way. Tricky.

Dipping the tile in a bucket of water

Dipping the tile in a bucket of water

Before placing the tile, I dipped it in water. These things suck up moisture, so it helped to wet them a bit to be able to shimmy them about without the tiles setting up so quickly.


Placing the tiles in the clay adhesive

And then the placement: quick, firm, and with pressure to set it down nicely in the clay. Ideally, you should not have to pick up the tile once it is down — picking it up with clay all over the back is annoying and tedious. That’s why getting the amount of clay adhesive right the first time is so important.

Once the tile is down, it’s time to level it. I ended up using a very short level almost exclusively. I gave up on using tile spacers along the way, because my lines were getting a little off in places, and it seemed futile. But really, using the spacers is very wise. Anyway, leveling is very tricky. Everything you do affects the next tile, so you really want to be as accurate as possible. April taught me to always plan for making the next row of tile easier than the last. Wise words. There were a few occasions when I would strike the tile with a hammer (with a wood block underneath, of course), but ideally, hand pressure should be enough to set the tile level.


Almost there...

Many, many hours later, the tiles were all in place.

Grouting and Cleaning the Terracotta Tile Floor

Grouting was fairly straightforward, but also time-consuming. We used a mix of 3:1 sand/clay as our grout. A thin, flexible piece of plastic was useful to drag along the grout lines once we had spread the mixture between the tiles. I’m glad April did most of the grouting, as I was pretty spent from a few long days of tiling.


Scrubbing the tile with a sponge

Finally, once the grout was dry enough, we cleaned the tile…. First, using a wide razor blade to remove excess clay and grout, and then sweeping up the excess. And then, with a wet sponge, scrubbing every single tile by hand. Wow. Not easy. It took about over 6 hours to sponge the floor alone.


The Final Results

Well, I gotta say, the results are very pleasing. The house is actually much brighter. It’s too early to tell how the tiles will hold up over time, but first impressions: they are visually pleasing, and easier to clean because you can see the dirt/dust more readily than on a dark earthen floor. I like that. (I love sweeping.) Combined with the newly lime plastered walls, the house looks even better than before, I think! Sure, there are plenty of imperfections in the floor (tiles not always level, grout lines that don’t line up), but hey…. this was our first go. What can I say.

Here’s a before and after look:

BEFORE: Earthen floor, all earthen plaster


AFTER: Tile floor, lime and earth plaster

Here’s a detail shot of those tricky wall edges:


Cutting, and placing, and cutting...

And check out how the tile floor reflects the light of the wood stove!


Cooking on the stove at night

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