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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  • Love the new floor Ziggy!
    And you did a great job. You should have seen my first tiling job- it was hillarious… to other people. I was not so amused.

    I think you should use the lime plaster all the way up to the roof though. Think how light and airy it would look white to the top!
    I built our house before I knew about cob, so it is a standard 2×4 with sheetrock interior. But we had to move in before it was finished, so we had the brown paper of the sheetrock facing out for about a year. When I finally got enough time to plaster it, the difference was like night and day. The house felt bigger, was much brighter, and the plaster evened out a lot of humidity problems.

    But great job on the house. I hope that it helps the mold and moisture problems!

  • simon

    wow… it’s always amazing to get back to this blog and see changes, progress and process… nice! the tiles look really pretty; and i am keen on following how the new floor will perform in winter’s cold and moisture…
    cheers from europe, simon

  • Mackey Mclelland

    wow, that looks great. congratulations

  • Mike

    This really looks fantastic! Well done!

    Love the look of the lime plaster too!

  • RyanC

    That looks Great!

    I still live with two of my first tile jobs and the uneven lines used to drive me crazy. After noticing flaws in almost every public bathroom I’ve been in the uneven lines don’t seem that bad anymore.

  • Dad

    Looks Great! See you soon.

    Love Ya


  • Brina

    Pretty! Seriously, it look gorgeous.

  • Your home looks great. The tile did really brighten up the place. I happen to like the mixture of textures and color on your walls. It is a nice combination of warmth and brightness. Great job!

  • Dennis Akotoye

    wow the house is looking splendid and i will use it in my project work and later in the future i will put up the samething in my country (GHANA)

  • That does look beautiful. You and others have got me all inspired to build in cob myself: I’m hosting a small cob workshop on the little parcel of land we can use as a permaculture garden (I figure if I host the workshop, I can learn and get a nice oven built by the end of it).
    Our only logistical problem is that the place I want to dog the cob out from is about ten metres below the site of the oven, but such is life in hilly places…

  • Wow, I am soo impressed with you cob house and new tile floor and lime wall plaster job, GOOD WORK Ziggy and April! I have a couple or questions and concerns about the house. First have you been able to improve ventalation at all, or would you recommend a good way to ventilate it while in the design process? Also how do you find the temperature in the summer and winter in the cob vs. strawbale in your climate, does it use up a lot of wood in the winter? Is it comfortable in the summer during 100 degree days? and How is the Living Roof doing? Is it keeping the moisture and heat out? You guys are a great inspiration, thank you for doing all that you do!

  • Spider

    Goodness! The lime plaster makes Gobcobatron look gorgeous. It’s a bit strange, but it seems bigger inside. After all the work you put into it, it’s only fair that your new floor looks so nice! Signed,

  • Jerry Thornton

    Love the Floor too Ziggy and April !! Here in South Florida we used a lot of Terra cotta tiles. In my experience we always soaked the tiles over night in containers of water. The tiles are so dry coming from Mexico we found that it sucked up all the moisture in the mastic and grout and with time would cause the tile’s bond to break with the floor. Just a hint….

    Great Job and I envy you wonderful beautiful people !!

  • My brother recommended I might like this blog. He was totally right. This put up truly made my day. You can not consider simply how a lot time I had spent for this info! Thanks!

  • Leigh

    Your tile floor looks beautiful! Shame you couldn’t take care of all the problems. Anyway, I wanted to tell you a trick I learned watching This Old House. A man who was a second gen tile craftsman, showed the best way to cleanup a tile floor after laying the tile. Once the grout is set enough you can, used dampened clean wood sawdust, sprinkle it over the floor and use a sponge to rub over the floor. It cleans it really well without picking up alot of your grout from between the tiles. Once your done, sweep the used sawdust up. And thats it. Try it if you lay a tile floor in your new place.
    Good luck!

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