Making a DIY Earthen Floor: two methods

earthern_floor

After completing the strawbale walls and the roundwood, reciprocal roof of the Milkwood Roundhouse, we wanted a gorgeous floor to complete this hand-crafted natural building. So an earthen floor was a natural choice.

There’s not much easily accessible info out there on how to make your own earth floor, however. So we’d like to share what we learned with you… 

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All this happened last Autumn. The walls and the roof of the roundhouse were up, and looking mighty fine.

Our floor options, as we saw them, was to make either a poured concrete or earth floor. In the interests of learning a craft and also minimising the embodied energy of the building, we really wanted to take the earthen route.

We had one problem – we didn’t know how to do it. And the info available was minimal. And most folks who suggested we do it, hadn’t done one either. So it was in all our minds, but not in anyone’s skillset.

Eventually, we settled on two possible techniques.

One technique offered low cost but extended drying time, and the other was going to be more pricey but would, in theory, get Floyd and Gigi into their new house faster.

We settled on the option with a higher cost and quicker drying time. If we had our time again, we’d probably use the other method. Live and learn.

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Brickies Sand method – step by step

Firstly, we laid down and compacted

  • 100mm of road base
  • 10-20mm of any sand available – (we used river sand) to protect the waterproof membrane above

Then we put down a waterproof layer (we used builder’s plastic) – this was to halt the possibility of rising damp in a very wet year

Next we laid down and compacted a 75mm layer of moistened brickies sand, and then it was time for the top layer.

The top layer

Ingredients: a 25mm layer of 4 parts of brickies sand, to 3 parts renderers clay

Method:

  • Make the mix in shovelfuls, the smaller the better, in a wheelbarrow. Mix well.
  • Spread it with a spirit level or screed, about 10mm higher than the desired finish level
  • Then compact it down with a steel compactor – still a few mm higher than the desired level
  • Screed it with the spirit level – to get it to the right height and level
  • Polish the floor with a steel trowel and a spray bottle with water to make it nice and smooth and fill in the cracks

The top layer must fully dry in order to go to the next step – curing the floor. Please be aware that in late Autumn, this  drying process takes much, much longer than you might like it to.

Curing the floor

Once all that was laid down, it was time to cure the floor. This step is magical (if a little long-winded) – the linseed oil and gum turps bond together around the sand grains to create this hard, smooth, gorgeous surface. Eventually.

The first primary ingredient for curing is boiled linseed oil – if you can, make sure you use RAW linseed oil, because it works as effectively as the other stuff and has less far less toxins in it.

The second primary ingredient is gum turps, or Gum Turpentine – this is derived from distilled wood. Not to be confused with Mineral Turpentine, which is a petroleum solvent. Just because gum turps is natural doesn’t mean it’s inert, however – you need lots of airflow and skin protection to work with it.

For the 28 square meters of the roundhouse floor’s surface, we used 8 litres of linseed oil. For each coat we mixed the ratio then poured as much as possible onto the floor without it pooling. We then applied it with a sponge mop.

Once each coat was absorbed, on went the next one. We did 5 coats all up:

1st coat – 100% linseed
2nd coat – 80% linseed to 20% turps
3rd coat – 60% linseed to 40% turps
4th coat – 40% linseed to 60% turps
5th coat – 20% linseed to 80% turps
6th coat – 100% turps

The end result is a very beautiful, slightly textured, very hard earth floor. It’s a pleasure to walk on, works as a thermal sink in colder weather, and is a beautiful addition to the roundhouse.

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This method took 8 weeks from start to finish, with high input costs due to all the brickies sand we used, and the endless hours of labour (mostly Floyd’s).

Next time, we will make an earth floor the way Sam Vivers, the natural builder that teaches the Milkwood Natural Building Workshops, suggested.

This method would result in lower material costs and less labor (though possibly longer drying time, depending on the climate).

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Sam Vivers taking students through a demo of earth floor building at Milkwood Farm

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Earthen Floor method 2 – the Sam Vivers method

  • Lay down 100mm of blue metal as base layer, then a thin layer of sand to protect waterproofing layer
  • Lay down builder’s plastic to provide waterproofing

Lay down 100mm of a cobbish mix – clay, sand and straw: 1 part of sand to 1 part of clay (depending on the quality of the clay) and long straw

Lay down 50mm layer of a thinner cobbish mix with added chaff (chopped straw) – 2 or 3 parts of sand to 1 clay (depending on the quality of the clay) and chaff

Lay down 10mm final layer of thin mix without straw – 3 parts sand to 1 part clay, using finer sand

Cure floor with linseed oil process as per the previous method

Note: each of the layers in this method needs to be completely dry before starting the next layer

So there you go – there are many other ways to build a long-wearing earthen floor other than these two methods, but that’s a start.

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However you achieve it, an earthen floor is a beautiful addition to a natural home.

It’s a hard-wearing surface, it looks gorgeous and , if the building has good passive solar design, this floor will collect and release heat into the house in the cooler months, and help to mediate the internal temperature of the house in the warmer months.

We’ll be showing students  all about how to make this sort of thing (as well as a roundhouse tour) as part of our Autumn Natural Building Workshop, which is a 4 days hands-on experience covering a multitude of natural building techniques.

Do you know of any other methods that work well? We’d love to hear about them!

>> More posts about Natural Building

40 Comments

  1. Posted January 28, 2014 at 7:32 am | Permalink | Reply

    Reblogged this on know it Now and commented:
    Great work really!

  2. Helen
    Posted January 28, 2014 at 7:42 am | Permalink | Reply

    Very interesting, thanks. On a trip to the Gibb River Road we saw a termite nest earth floor. There seems to be something the ants leave behind that help it bond well with long lasting properties. The mortar used in the walls was also from the termite nests which may be particular to that region.

  3. Posted January 28, 2014 at 7:59 am | Permalink | Reply

    Reblogged this on Oldschool's Notebook.

  4. Posted January 28, 2014 at 8:05 am | Permalink | Reply

    Fantastic! Can’t wait to make my own! =)

  5. Meg
    Posted January 28, 2014 at 11:02 am | Permalink | Reply

    How does it wear? Will it scratch under chair legs or chip/dent if something is dropped? I love the idea but wonder how durable it would be for our family of five plus dogs (who come inside). Do you sweep it? Can you mop it? We want to build our house using natural materials but it needs to be durable and easy to live with. It looks beautiful.

    • Posted January 28, 2014 at 11:07 am | Permalink | Reply

      it’s hard wearing so far – yes you can mop it – chairs need those rubber thingies on their leg ends, and if you dropped a brick on it’s end on it i’d say you’d get a small chip or dent… but that would be the case with many floors :)

      It’s not concrete, that’s for sure. But it’s bloody hard.

  6. Meg
    Posted January 28, 2014 at 1:06 pm | Permalink | Reply

    Thanks for the info- it’s good to know :)

  7. Posted January 28, 2014 at 9:57 pm | Permalink | Reply

    This post couldn’t have come at a better time. I didn’t realise that a clay flood could be so simple, and require so few materials. I think I’m sold.

  8. Posted January 28, 2014 at 10:39 pm | Permalink | Reply

    This is the home of my dreams. Beautiful small things that make’s our lives pleasant .

  9. Posted January 29, 2014 at 1:48 pm | Permalink | Reply

    What a fantastic how-to and explanation of what you’d have done differently. The end result is truly beautiful.

  10. Rebecca
    Posted January 30, 2014 at 1:11 am | Permalink | Reply

    You floor looks fantastic! I did mine more along the lines of the second method you described and I wouldn’t recommend it. It looked and felt fantastic initially, but then I discovered that it was actually pretty fragile. Once the surface is broken it is loose sand underneath. Appears the sand and clay somehow separated in the drying process. Haven’t figured a good way to patch it as the linseed/terps sealant has made the surrounding surface impossible to stick new mud onto.

    For the reader above with dogs, I would definitely ask someone who has lived with dogs on a mud floor before I lashed out on it.

    Don’t underestimate how labour intensive it is!!!

  11. mar-kelly
    Posted January 30, 2014 at 7:00 am | Permalink | Reply

    when you say builders plastic, is it a plastic sheet you lay down or is it a plastic mixture?

    • Posted January 30, 2014 at 11:33 am | Permalink | Reply

      Plastic sheeting – anything available what is thick enough now to fall apart, really -

  12. mykombiandi
    Posted January 30, 2014 at 1:50 pm | Permalink | Reply

    Great job guys. I intend to build a strawbale home and I’m thinking of a straw bale round house for a studio. A earthen floor is a great idea. Thanks for the advice and great post.

  13. Posted February 3, 2014 at 5:11 am | Permalink | Reply

    Reblogged this on The People's Caravan.

  14. Posted February 4, 2014 at 10:34 am | Permalink | Reply

    Is the linseed/gum terps sealant sufficient to prevent swelling and cracking during periods of extreme wet/dry?

    With a 4:3 mixture I’d imagine you would end up with a pretty stiff material. It would be absolutely imperative that you get your subbase compacted well. Any settlement in it, with a stiff floor on top, would result in cracking of the floor and then moisture ingress through the cracks.

    It looks to be a delightfully warm, inviting floor. It would have good thermal properties too I’d imagine?

    • Posted February 4, 2014 at 11:51 am | Permalink | Reply

      it’s pretty darn hard. And yes, the subbase was VERY well compacted – we don’t expect there to be any further settling.

  15. Bernie Walton
    Posted February 4, 2014 at 10:45 am | Permalink | Reply

    A 93 y o. bushie I knew told me that termite nest soil is indeed a very hard durable floor surface !–but I would definitely not use linseed oil–which smells horrible ! & I suspect-will always smell horrible.

    • Posted February 4, 2014 at 11:52 am | Permalink | Reply

      Actually, it smells great – the combo of turps and linseed smells like a natural furniture shop – or that’s the comments we’ve got so far :)

  16. Posted February 4, 2014 at 10:53 am | Permalink | Reply

    Nice work, we are installing an earth floor in our new house after being inspired by a mate having done one up north nearly 20 years ago.
    For those who are looking to get this kind of floor ‘approved’ this drawing from our engineer, Martin Chambers, might help: https://picasaweb.google.com/lh/photo/DVrGyB4FdEXCJquG4_2RtdMTjNZETYmyPJy0liipFm0?feat=directlink
    Our building surveyor has indicated that whilst this is outside of the code, he is likely to apply a ‘deemed to comply’ assessment such that the floor treatment passes muster.
    Thanks again and great work as always,
    Cheers, Darren Doherty

  17. Christian
    Posted February 4, 2014 at 11:28 am | Permalink | Reply

    I have heard of people in India (I think) using cow dung in the mix, which might help the sand and clay glue together better than straw alone.

  18. Rosie McDonell (laguna earthouse)
    Posted February 4, 2014 at 3:38 pm | Permalink | Reply

    We’ve been living on an oiled earthen floor for 6 years. Incredibly beautiful, hard wearing, moppable and great at storing that winter sun and keeping cool in these hot summers. A slightly different technique – we put in a base of aggregate of varied sizes for it to all key in with a clay/sand mix on top. We put carpet down and lived on it for a year to compact it naturally. Then added the final clay/sand mix with stalks of our microlaena grass (native weeping grass) instead of straw. As this final layer was only about an inch thick it dried quickly and we could add the liniseed/gum turps mix as above. Love it.

  19. Phill
    Posted February 5, 2014 at 5:54 pm | Permalink | Reply

    Oxblood use to be the cure method of the pioneers I’ve seen one and which was pretty impressive shiny finish ,the floor was over a hundred years old.

  20. Posted February 8, 2014 at 7:16 am | Permalink | Reply

    Reblogged this on X_trous Notes and commented:
    Mesti rumah ni sejuk, lantai tanah liat. Hihi~

  21. Posted February 8, 2014 at 6:57 pm | Permalink | Reply

    I tripped across this link 18 or more months ago and saved it for future reference. http://www.enn.com/green_building/article/29222 It has links attached. I have no experience to tell if it’s good or not but it’s so awesome to see someone doing it and reporting such success. :)

  22. Posted April 20, 2014 at 12:41 am | Permalink | Reply

    Thank you guys for sharing these wonderfull ideas. I am planing my big build next year and I’ll be using natural building methods, no doubt about it. I’ll post my side of story how it goes. Thank you

  23. Posted May 9, 2014 at 2:32 am | Permalink | Reply

    Love it! Any chance you could clarify for the building-impaired, what is ‘road base’ and what is ‘blue metal?’

  24. Posted May 9, 2014 at 7:47 am | Permalink | Reply

    Colloquially road base is a densely graded crushed rock, generally with a maximum stone size of 20mm and a good mix of finer stones, sand and fines.

    Blue metal, or aggregate is a hard – generally a basalt – rock gravel of a single size (5, 7, 10, 14 or 20mm). It’s the stuff they put down onto bitumen when they seal a road.

  25. Jolieske Lips
    Posted May 28, 2014 at 8:35 pm | Permalink | Reply

    We were much more slaphappy. I wanted to be connected directly to the earth so we didnt use any plastic, but we are midslope so in a well-drained position.
    We used just brickies sand straight onto the ground which had been levelled with a bulldozer and been walked on for four years while we built the round stone house.
    Original plan had been for 10cms thick but we ended up with less (6-8cms?) as we ran out of sand and were under a tight time constraint so no time to get more. It was raining the day we did it so the sand piled outside got wetter as the day went on. Took us ages to wheelbarrow it all inside.
    We used a plate vibrater (not compacter) to even it out, but my husband reckoned it was like working on a water bed! It would go down at one side, and up on the other. We smoothed it out best we could and left it for 10 days to dry out (late Feb) then gave it 2 coats of boiled linseed oil and gum turps (50/50 ratio) we cant remember but maybe a day apart and three days later had our wedding party on it!
    17 years later it is a bit chipped and gauged but full of character. Kitchen area gets chips more than any other area and as we are so slack we ignore them till they get big, then simply add some more sand and seal – it is a lighter patch of course but just adds to the character.
    We look at it and wonder if we should – in sections – chip the top layer off, add more sand and smooth it out really nicely with a trowel (like we didnt have time to do the first go round and how we did on one big repair job and it is really nice and smooth) and re-seal and that would then see us out ie another 20 years or so, but it would be such a big job, so we might one day just reseal the lot as is – or not and just do repair jobs as needed.
    It is a wonderful floor – sooooo much nicer to walk on than concrete and much warmer. We love it!

    • Posted May 29, 2014 at 8:45 am | Permalink | Reply

      you were an inspiration for our floor, Jolieske! Thanks for all your help :)

  26. Posted June 29, 2014 at 8:12 am | Permalink | Reply

    Kirsten, about to build in forbes with a floor similar to this, how has yours gone for hairline cracks and crevices etc??
    I have seen some floors that are riddled with cracks although a contrasting grout can be added so as to simulate the flagstone effect.
    thanks in advance.
    James

  27. zey
    Posted July 9, 2014 at 1:24 am | Permalink | Reply

    can you suggest an alternative for blue metal?

  28. zey
    Posted July 9, 2014 at 1:33 am | Permalink | Reply

    I find this very interesting. Have done some tests, like its compressive strength?

  29. Posted July 9, 2014 at 2:05 pm | Permalink | Reply

    I would advise against using blue metal (aggregate) of a single size anywhere in a pavement (after all what is being built is a pavement in function). Material of a singular size will tend not to compact well and by extension it will be very difficult to compact any material on top of it. You need a material with a reasonable grading (that is particles of varying size) to fill the voids left by the largest particle in the material and ‘lock’ the granular matrix together. A fine crushed rock product (road base) – maximum stone size ~20mm or so – would be perfect in this application and I note Kirsten’s method uses this sort of material.

    • zey
      Posted July 10, 2014 at 2:42 pm | Permalink | Reply

      Thank you! i was planning to make a sample of this and test its strength.

  30. Posted July 9, 2014 at 9:04 pm | Permalink | Reply

    I am a big fan of this, looks great. I was just wondering what the detail between the earthen floor construction and the rubble trench / straw bale wall looked like? The earthen floor method 2 construction is about 290mm deep. If this 290mm was added onto the existing floor level, was there a barrier between the straw bales and the floor construction? If 290mm was excavated for the floor construction, was there a barrier between the rubble trench and the floor construction? Thanks in advance for you help!

  31. ey
    Posted July 22, 2014 at 12:53 pm | Permalink | Reply

    do you guys have any suggestion other than linseed oil? Thanks in advance!

    • Jolieske Lips
      Posted July 22, 2014 at 6:20 pm | Permalink | Reply

      the thing about linseed oil apparently (from an industrial chemist staying with us) is that it has a very complex molecular structure and that is why it is such a good sealant. we were advised double boiled as that stops it going rancid.

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