Earthen Floors

[dropcap type=”circle” color=”#ed6f0e” background=”#422014″]E[/dropcap]arthen Floors are one of my new found favourites in Natural Building. Not only are they very beautiful, but earthen floors are also exceptionally comfortable under foot. If you are thinking about having an earthen floor in your home you have come to the right place. This page will provide you with some of the basic information, while Earthen Built can provide professional consultation and installation.

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Benefits of Earthen Floors:

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  • aesthetically pleasing
  • hold & radiate heat well
  • comfortable under foot
  • very versatile
  • can go over a variety of substrates
  • form flexible
  • ecological materials

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Tools & Equipment:

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  • sand, clay, fibre, water
  • mixing drill, mortar mixer, cement mixer, hoe & trough, or tarp
  • screed boards, or laser level
  • wooden floats, long darby float, steel trowels
  • knee protection
  • tape & wall protection
  • fans, dehumidifiers (ideal)

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Location Considerations:

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  • Earthen floors are great in just about any space, even bathrooms and kitchens.
  • The only place I would not recommend an earthen floor is in a workshop, where large and heavy objects may damage the floors too much.

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Thickness:

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  • 3/4 inch minimum
  • 2 inch maximum per layer

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Options with Earthen Floors:

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  • in-floor heating
  • can inset tiles, stones, etc.
  • thickness
  • colour

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Pre-pour Checklist:

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  • seam planning if area too big for one day
  • solid sub – no flex
  • structure can hold weight
  • floor is insulated

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Substrates I have worked on:

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  • earthen
  • wood
  • concrete slab

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Floor Project Galleries:

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[tab_item title=”About”]This is an earthen floor done over an earthen substrate. The substrate is built up in layers including a drainage layer, insulation layer, and cob levelling layer. The cob levelling layer had been done some time before the finish layer and had seen a lot of traffic which had caused the floor to be quite un-level. Also, as is often the case with cob, the sub floor had many big cracks in it. The client did not want to do another levelling layer or scrape back the high spots. He understood the risks of laying a floor on such a variable sub and we offered him a few options.

We did the finish floor in three days and used three different techniques. For the first section we trowelled down a thin coat of finish floor mix, spread out clay soaked burlap, then trowelled out the finish coat. This took the most time of the three techniques, but dealt really well with the cracks.
The second day we opted out of the burlap and went with a somewhat dryer mix. This one proved to function the worst, and a lot of cracks shadowed up through the finish.
The last technique we used a fairly wet mix, again without burlap. We were pleased to see a lot less cracks of smaller sizes come up in this last section.I was able to close up most of the cracks throughout the house and achieve a nice smooth floor.

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  • Always plan in advance where you are going to stop work for the day so that if your seams are going to show they look intentional.

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To add colour to the floor we put the pigment in the oil mixture. We used a raw linseed oil thinned 75% for the 1st coat, 50% for the 2nd, 25% for the 3rd, and not thinned for the 4th and final coat. The colour did a nice job of tinting the floor, but I would recommend a colour wash before the oil if you want stronger pigmentation.
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[tab_item title=”About”]This is a floor I did for myself in a rental in Cowichan Bay. As I was doing this job pro-bono, I took advantage of this project to try out a few theories I had about floors.

 

Mix:

We really pushed the limits on the sand to clay ratio to see how little clay we could get away with. Since we used locally harvested materials it is hard to give a recipe that would mean anything beyond those specific materials. It came close to:

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  • 12 parts sand
  • 1 part clay slip
  • 1 part chopped straw

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Application:

There was a concrete slab in the room already, so I didn’t have to do anything in terms of prep besides sweep. Because the slab wasn’t completely level (the centre was higher than the edges by 3/4 of an inch) and I wanted to make sure I had at least the minumum 3/4 inch thickness, I decided to use screed boards instead of my laser level. The difference is not enough to notice under foot, so I wasn’t worried at all about this discretion in level. When it came to the doors I had nearly 2 inches to come up level with the threshold. I built up some graceful “ramps” and even set in some slate tiles. The tiles were more for my house-mate who needed to have access to the closet-turned-coldroom. They worked out great.

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  • used screed boards
  • floated & trowelled 3/4 inch mix
  • inset 5 slate “stepping” tiles at entrance

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Colour:

The real test of the mix came when I went to add colour. Adding surface colour was something pretty new to me with floors at this point, so it was a great experiment. I wanted to do a few colours blended to give a stone-like look.
With my sponge full of coloured slip I dabbed the floor; and that’s when the four letter words started. This wasn’t working, there was so little clay in the mix that the sponge was just picking up the sand and making my nicely trowelled floor real rough.
I tried trowelling the colour around too, but wasn’t happy with the look.
My third attempt was with my special soft bristled brush I use for alizes. Bingo! The brush didn’t keep the floor as smooth as the trowel, but at least it didn’t rough it up as bad as the sponge either. The other thing about using the brush was that I had to go with just one colour.

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  • sponge – too little clay in mix, very rough
  • trowel – smooth, unpleasant asthetic
  • brush – one colour, a bit rough

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Finishing & Sealing:

Once this dried it was time to oil, sand, and wax. Normally I would have hard-trowelled after the colour and before the oiling, but I wasn’t going to take the chances of the colour coat coming off as I worked. I had to wait until I sanded to smooth this floor out.
I used a raw linseed oil uncut with thinner for 3 coats. This was also a bit of a theory tester for me.
Once the oil soaked in for a few days it was time to test my theory and sand the floor. I had a 15 inch round upright orbital floor buffer for this with my 3 varieties of grit buffers/sanders. I started light, with the middle grit pad. Nothing. I went up to my heavy pad. Still absolutely nothing! So I brought out my angle grinder, that’s right, my angle grinder! I did a test patch on a sample box that I had made along with my floor. It seemed to work real well. So I went for it in my room. It was slow going as I took this little 4 inch round bit of 80 grit sand paper to the roughly 250 sq ft floor. Some sections were quite rough and I really put some weight into the grinder. It worked beautifully though! I couldn’t believe just how tough I was on this floor and it just took it perfectly.
After a good sweep I took out the finishing wax I got from Claylin and sponged it on nice and thin. My favourite tool for this is a floor sponge on a long handle. After a few days I took the stand-up buffer out again and used my softest pad to buff out any excess wax and polish it up.

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  • 3 coats uncut raw linseed oil
  • sanded with 80 grit on angle grinder
  • 1 thin coat Claylin finishing wax
  • buffed with white floor buffing pad

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Besides the theories I got to test, and some unexpected experiments along the way, some of the greatest advantages to doing this floor were to intimately experience how long a floor takes (I was camped out in the living room while working on it) and to gain the experience of living with an Earthen Floor. I must say, I fell in love with these floors. It was so comfortable, and exceptionally durable. I feel it safe to confirm that the hardness and durability are on par with a good hardwood floor. The floor was also just so beautiful, I never got tired of looking at it or showing it off to people that came by the house.

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[tab_item title=”About”]In this house we worked on both earthen substrates and wooden substrates. We were lucky that the cob substrate had little to no cracking, so a nice wet mix throughout the main level of the house was an easy decision. Upstairs, on the wooden substrate, we tacked down butcher paper to protect the wood from swelling from too much water. On top of this we trowelled out the same wet mix as downstairs.
There were some areas we had to troubleshoot with this project. Some were struggles with drying, which caused some good grass to grow, while others were with people walking on wet floors, causing damage and footprints. There was also some cracking upstairs that we were able to close up. For the worst of it all I ended up re-soaking the floor and re-trowelling the entire section with a little added clay slip.
The client wanted a variety of colours as well, so we did some nice colour washes under the oil. We did red, purple, yellow, and natural coloured floors, some even blending into the other.

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