17 January 2014

Adobe Floor Basics - How to build a dirt cheap floor

Seems crazy, right?  A dirt floor, of all things!  Well, time for a perception shift...

Adobe floors are lusciously beautiful and quite durable.  And best of all, in most regions they can be made from local clay soil.  (Which makes them dirt cheap...sorry, couldn't resist.)


adobe floor in a strawbale cottage in WV

The Concept

An adobe floor, or earthen floor, relies on the sticky binding properties of clay...one of the most versatile building materials I know of.  Clay expands when wet, creating sticky platelet particles, like a bunch of suction cups.  Add to the clay ample course sand, to increase compressive strength and control shrinkage as the clay dries.  Finally add fiber, to increase tensile strength and knit everything together, like reinforcing bar in concrete.  The finish mix is essentially the same as adobe or cob.  And the installation is similar to a concrete slab, only without the environmental impacts or cold nature of cement.

What I describe below is the method I use to install an adobe floor.  It is by no means the only method!  I recommend reading with the intention to gain an understanding of the concept...the function that each layer serves.  This way you can adjust and experiment while being sure to include the primary functional characteristics (most particularly to keep moisture out of the floor).

The Layers

A typical adobe floor includes a build-up of layers, each with a purpose.  I describe each layer below, including the function it serves and (in some cases) alternatives you can experiment with.  This example demonstrates a floor installed "on grade", similar to a concrete slab.  You can also install the adobe on a framed floor, but be sure to stiffen the joist framing to minimize flex, otherwise your floor will crack over time.  There are a variety of methods for building up the floor layers, from single pours to multi-layered finishes.  I am sharing a basic version that is conceptually similar to pouring a concrete slab.  I find that this system performs extremely well and is very forgiving to install.

sketch of adobe floor layers

So, starting from the bottom up...

#1: The substrate

You want your floor to rest on solid ground (or a stiff framed floor with little flex).  If you have movement below, it means cracks up above.  So you want structurally strong, compacted earth to build on.  The ground should be free of topsoil or high organic matter, since the organics will continue to decompose and shrink in volume over time, leaving you with voids below your adobe floor.  So dig down until the soil feels solid and compact.  You may even want to go over the ground with a hand tamper to ensure compaction.

#2: The capillary break

Next you install several inches of gravel to provide a capillary break that prevents any potential liquid water in the ground from rising up into the floor.  I use 4-6" of pea gravel or angular 1-inch stone.  If you live somewhere where pumice is commonplace (or any insulating mineral/rock), you can substitute the pumice for the stone & the insulation (#4), since the pumice will provide both qualities.

#3: The vapor barrier

Next you lay a vapor barrier that covers the entire floor area.  This provides your final moisture control for the adobe, blocking any air-borne vapor (from evaporated ground moisture).  I use 6 mil polyethylene sheeting for this, exactly what is used to prepare a concrete slab.  The plastic is obviously not natural, but it's excellent insurance.

#4: The insulation

This is probably the layer that is most often left out, but it can dictate the energy performance & your comfort level.  If you live in an exclusively hot climate, then you can skip the insulation, because a cool floor is beneficial.  But if you heat your building at all...at all...then you want to keep the heat inside.  If you do not have insulation below your floor, then you are, in effect, heating the endless thermal mass of the ground below.  I use R-10 insulation for a typical floor and bump up to R-15 if the floor will have radiant heating in it.  You want that heat to follow the path of least resistance into your space, not down into the ground.  And you need that insulation to be non-biodegradable, otherwise it will compost under your floor and disappear over time, leaving you with a cracked & heaving floor.  This is one place where I will use rigid foam, since the reduction in energy over time quickly offsets the impact of the foam manufacture.  For a natural alternative, you can use rock wool insulation or an insulating mineral, such as pumice or perlite.

vapor barrier (black plastic) with insulation above

#5: The base layer

I do a 2-layer adobe floor, mostly because this allows me to pour the thick base layer before the exterior walls are completely closed in.  That extra air-flow speeds up drying time (and eliminates a highly humid interior later in construction).  I use the same proportions I would for cob, which is generally 15 to 25% total clay plus 75 yo 85% concrete sand.  The difference is that I add lots more water.  With cob, the wetter your mix, the more your cob wants to splooge on your walls, so it prevents you from building higher until the material dries.  However, with a floor, you want to be able to pour it, like a really thick liquid.  (I use about the consistency of chocolate pudding.)  If I am using clay soil from the site, I sift it pretty large...through a 1/2" screen is fine.  To this mix, you want to add long fiber, and lots of it.  The fiber knits the floor together and helps prevent cracking in the clay.  I use straw, since it is abundant in my region.

The process for laying this layer is pretty simple.

  1. make a batch of your mix
  2. place the mix at the farthest corner of your floor, where you are going to begin
  3. make sure you have height reference points in place (such as a perimeter beam or braced ledger boards)
  4. roughly pack the mixture into place, being sure to push into any corners or voids (you can literally throw the adobe into the corners to be sure you get good fill); make sure your material is filled a bit higher than you want your finished layer to end up
  5. level the floor with a long, straight 2x4 by holding each end of the board on your ledgers (so you know your height) and then shimmy the board back-and-forth while pulling slowly toward you (the longer your leveling board, the more hands on deck you need to shimmy it); as material builds up in front of your board, it makes it more difficult to move the 2x4, so simply stop, scrape the excess out of your way, and carry on
  6. then let the floor dry completely (and don't let it freeze until it is 100% dry)

Note that it is perfectly normal to get some sprouting in your floor as it dries.  Do not be alarmed if this happens!  It's just seeds from your straw confusing your floor for a garden.  As soon as the floor dries, the sprouts will die, leaving behind some additional fiber reinforcing from their root structure.

Another option for this base layer is to make adobe bricks.  You are using the same exact mixture but placing it in forms and then letting the adobe dry out in the sun.  The benefit here is that you can carry on with construction, without having to wait for a thick, wet floor to dry so you can walk around unimpeded.  Once your bricks are dry, you lay them like patio pavers in a layer of sand, tamping them to level as you go.

leveling the adobe with a long, straight 2x4

this first layer just needs to be level, but it can have pock marks
(this 550 SF floor took 1 day for about 15 people to install)

#6: The leveling layer

There are a few approaches you can take for this layer.  What I do is float this layer smoooooth and then polish it as it hardens.  Some people float this layer reasonably smoothly, and then apply a super thin layer for the desired texture.  The benefit of polishing this layer as your finish floor is that you avoid the extra step of additional layers.  The benefit of applying a thin final layer is that it's easier to control the texture of a thin coat than it is to control the texture of a thicker poured floor.  So you can decide which is less stressful to you...  But either way, the goal of this layer is to end up with a floor that is level (and if it's your finish, then level & smooth).  In the first layer, small imperfections are not a concern, but this layer is what you will see for years to come.

This second layer uses the same adobe mixture as the base layer, with two modifications:

  1. if using clay soil from the site, I sift it a bit finer...I use 1/4" screening for this layer
  2. any straw in this layer should be chopped to 1" or shorter
Why these changes?  Because smaller particles allow you to float the floor to a finer finish.  I don't always use straw in this layer of the floor, since it will show in the finish surface and not everyone wants/likes that look.  If you eliminate the straw, then it is absolutely crucial to get the ratio of clay to sand perfect.  To do this, make some test patches of your floor and see how they dry.  If they are crumbly and weak, there is not enough clay.  If they crack, there is not enough sand.

The process for laying this layer is as follows.

  1. make a batch of your mix, making sure that it is fairly creamy; wet it just enough so that when you hold a handful flat in your hand it keeps a mounded shape until you vibrate your hand slightly, then it flows like a liquid
  2. make sure you have height reference points in place; I use screed boards that are the same thickness as the floor I want to install (for example, I use a flat 2x for a 1-1/2" thick floor)...see photo below
  3. start at the farthest corner of your floor (and work your way out toward an exit path), and work in swaths that you can easily reach without over-extending your body
  4. roughly pack the mixture into place, being sure to push into any corners or voids (you can literally throw the adobe into corners to be sure you get good fill); make sure your material is filled a bit higher than you want your finished layer to end up
  5. use a very straight 2x4 (or 2x6) that is long enough to touch 2 of your screed boards, push down to create firm contact with the screed boards, and then shimmy your board side-to-side to level the floor; as material builds up in front of your board, simply stop, scrape the excess out of your way, and keep going; the floor shape should be pretty level, but you may have some voids here and there
  6. I then use a wood float or a magnesium float and fine-tune the surface; add little bits of material if you need to fill any voids, and just keep working the surface until it is level and reasonably smooth (see photos below for examples of what it will look like)
  7. your final pass while the floor is wet is with a flexible pool float; this will bring a bit of water (and with it, clay) to the surface and allow you to really make the surface look pretty; but don't go over the surface too much here, or you will bring too much clay to the top and the floor will crack as it dries
  8. continue until your floor is completely installed, moving the screed boards as you go
  9. Finally you will burnish the surface of the adobe floor as the clay becomes leather hard (firm enough that you definitely couldn't trowel it anymore, but soft enough that you can just barely make a thumb print in the surface); slightly mist a small area with water and make quick, tight circles using a very flexible float made from steel or plastic; the amount of pressure you can apply will depend on the dampness of the floor; you should see a slight sheen on the surface as you burnish and any hairline cracks will be pushed closed; if you wait too long to burnish, the clay will be too dry & hard, and you will need to skip the burnishing
  10. then let the floor dry completely (and don't let it freeze until it is 100% dry)

beginning the final 1-1/2" layer

floating the floor level, first with a 2x4, then with a magnesium float to fill all the voids

working from every direction to meet in the middle

a flexible steel float makes the finish super smoooooth

you can see each step...rough placement, wood board leveling, and smooth finish

Watch my trowel primer to understand different types of floats and how best to use them:


#7: The finish

There are several options for finishing your beautiful adobe floor.  (Have you noticed the trend that there's never just one way with natural building?)

If you chose to apply a thin final layer of clay, you have 2 options:

  • apply an 1/8" finish layer, much like a clay plaster, but applied to the floor; when this layer is dry, seal as described below; you can find more info and a recipe HERE
  • apply 1 to 4 coats of clay paint, also call "alis"; when this layer is dry, seal as described below; you can find more info and a recipe HERE
If you chose to burnish your floor, then as soon as the clay is completely dry, you are ready to apply a sealer.  The sealer densifies the top layer of clay (making it more durable & scratch resistant), prevents dusting (so you don't get clay on your butt when you sit on the floor), and reduces absorption (so makes it more stain-proof & easy to clean).  The most common sealers are hardening oils, which react with oxygen in the air to chemically change into a hard, transparent, water-resistant, but breathable resin.  Hardening oils include linseed oil (derived from flax seeds), hemp oil, tung oil, walnut oil, etc.  The oil is applied in multiple layers, and each subsequent layer is thinned with a solvent to promote deep absorption into your adobe surface.  Common thinning solvents include citrus solvent (d-limonene based, ie orange peel) or mineral spirits (petroleum based).  There are alternatives to oil & wax sealers, so feel free to do additional research & experimentation on that.  (The most intriguing of all sealers to me is cow urine.  Yup, not a typo...cow urine.  Traditionally used in parts of Africa and apparently makes for a stunning floor.)  You can also add pigment to your sealer if you want to enhance the color of your floor.

Here are the layers I most commonly use to seal a floor:

  • 1st coat - pure hardening oil (1 gallon covers approximately 200 SF when applied full strength)
  • 2nd coat - 80% hardening oil with 20% thinning solvent
  • 3rd coat - 60% hardening oil with 40% thinning solvent
  • optional 4th coat for high traffic or damp areas - 40% hardening oil with 60% thinning solvent
  • optional beeswax paste to finish - if you want a really luscious surface that feels like leather, then I highly recommend a final coat of beeswax paste buffed into the surface of your sealed floor

Note on smell...the oils harden by oxidizing, a chemical process that offgases an aldehyde compound.  Aldehydes are technically a VOC, though the particular compound offgassed from oils as they oxidize has extremely low toxicity (unlike their cousin, formaldehyde, which is carcinogenic).  However, there is definitely a smell that can linger (especially from linseed oil) and some people with respiratory issues may experience discomfort.
the finished floor

Additives

There are loads of variations on the mix for adobe floors, including additives to enhance various properties.  Common additives include cow manure, prickly pear cactus juice, hydrated lime, milk protein (casein), wheat paste, pigments...even blood protein.  Look for a future post describing the benefits and characteristics of the most common adobe, cob, and clay plaster additives.  (I'll update with a link here when that post is complete.)

Recommended Reads

This is a recently published, comprehensive book by Earthen Floor guru Sukita Reay Crimmel.

 Purchase "Earthen Floors"

141 comments:

  1. Fantastic information Sigi! Thank you so much!

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  2. Super explanation.....wonderful input, as always, much gratitude

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  3. Can you build this earth floor on top of an old concrete slab? If so which layer can you start the process at?

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    1. yes, you absolutely can. If you are sure the concrete is insulated & has a vapor barrier, then you can just start with the first layer of adobe. However, if you are not sure, then I would put down a sheet of vapor barrier, some insulation, and then start your adobe on top of that. Since you already have a solid base with the concrete, you can actually just do a single layer...ie, the top layer of adobe...you don't need all 6+ inches (but either way, I would make sure you are insulated & have that vapor barrier).

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  4. WOW Great write up. thank you so much for the wealth of information. I will definitely be putting this to use in the house I will be building! Printing and posting to the vision board as we speak :)
    If you get a minute you can see what I will be making here:
    http://www.themodernnatural.com/2014/03/the-house.html
    I just like to share with fellow natural builders.
    thanks again

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  5. Thanks for the clear and in depth instructions. About a week ago I poured the first layer (4inches) of my floor according to your tutorial. It is now hard enough to walk on and I was wondering if I should tamp or trowel it down for more compaction. When I tried in a corner it just made it mushy and lots of little cracks formed. Do you just leave it alone until it is dry without worrying if there are small spaces or airholes from the pour? Thanks so much for all your sharing!

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    1. The first layer you can just let dry as is. No tamping or troweling needed. A rougher textured surface actually keys in better when you do your final layer. That said...there shouldn't be air spaces in that first layer. When you place it, it's important to push and work all of those air pockets out. That said...little air pockets won't effect anything, so don't stress about it. Hope this helps.

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  6. I was very pleased to find this site.I wanted to thank you for this great read!! I definitely enjoying every little bit of it and I have you bookmarked to check out new stuff you post.
    Floorsanding Gold Coast | Polished floors Brisbane

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  7. Hi Sigi, great article thankyou! Just wondering, we have a painted concrete slab floor that we want to surface with an earthen floor. Is it a problem that the slab is painted? Will it affect how the earth floor "sticks" or stays put? Thankyou

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    1. The slab being painted isn't really a problem. Bigger issue would be to make sure there are no cracks in the concrete slab and that moisture is not wicking up through the concrete from the ground below. As long as both of those variables are ok, then your earthen floor should work on top of the concrete slab just fine.

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  8. I've been doing web searches, and I can't figure this out, maybe you can help. If we want to purchase land in Eastern Tennessee (at 3000 feet in the Smoky Mountains) how can we find out if the land contains clay to use for the floor/walls of a strawbale/cob structure?

    Thanks if you can help!!

    Laurel

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    1. Hi Laurel, Basically you need to bring a shovel, dig down below the topsoil add a bit of water to get a workable consistency, and then here is a video with instructions from there: www.youtube.com/watch?v=hh211b8b5FE

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  9. Hi, we are on year 2 of our earth floor and it seems we've made a mistake. It flexes to much, causing cracks and dust to 'poof' up from the cracks. We continue to linseed the cracks but it seems to make them worse, causing the top layer to peel back and expose We put 1 1/2 inch ridged foam down on top of 3 inches of gravel (not leveled the best I assume), then wire rebar and then the clay portion. I'm wondering if you have any experience with this? Can I drill a hole thru the clay and insulation and put "Great Stuf Foam" down in the dips and hope that evens it out? We really (obviously) don't want to tear it out, but it is a main room and the clay dust is really getting bad. Thanks!

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    1. Sorry to hear about your floor. It sounds to me like the base layers were not seated well. Everything below the floor needs to be solid. No wiggling. No movement. Nothing that will compact over time. Just really solid. If there is significant movement below, then you will get cracks in the floor above. This is even true for concrete slabs. It's of course impossible to diagnose the problem without seeing it, but that is my best guess as to what is going on. Unfortunately, I don't know a good fix to the problem. You can continue to repair the cracks. I would use your adobe mixture, not straight linseed oil, to fill the cracks. Linseed oil is a sealer material, not really a filler. The other issue with your floor may be the rebar. Not sure why that was used, but it doesn't provide any benefit. It may also be causing the problem...if it's the steel grid that's moving, then it will move your whole floor, and thus cause cracks all over. If it were my home, I would remove the floor completely. Ditch the rebar. Seat the insulation to be sure it's down firmly with no wiggle. And then pour a new floor above. Use lots of straw in the mixture. And make tests of different ratios of your materials before you commit to a mix...that way you know you have the strongest mix possible. You may also want to purchase the Earthen Floor book that was just recently published by Sukita Reay Crimmel. Good luck!

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  10. I have never considered making floor out of this kind of material. I also saw in another article that you made benches out of the same basic material. I am really a fan of going back to the basics. Thanks for the great inspiration. http://cedarshop.com/our-company/

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  11. We're planning on building an earth floor, and had some questions. If you should wait until the first layer is completly dry before you pour the second one, how do the "glue" together? Do I have to water the first layer before I pour the second one?
    Thanks a lot for the tutorial, it's really helpfull, even in this side of the planet (I'm writing from Chile, southamerica)

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    1. How fun that you are building an earthen floor in Chile! And I'm so glad that this info helps. So for your great questions:
      1) definitely let the bottom layer dry completely before adding layers on top. This is so that any cracking that may occur will happen in that thick lower layer. Then you can adjust the mix if you need to for the upper layer, and the top layer will fill in any cracks that were in the lower layer.
      2) the two layers don't really "glue" together the same way plaster does. The clay from each sortof bonds between the two, but mostly gravity is what is holding them in place (plus any imperfections or cracks in the lower layer help to physically "key" the upper layer.
      3) definitely definitely dampen the lower layer before adding the top coat. This does 2 things. First, it slightly reactivates the clay in the first layer and helps it be sticky for the upper layer. And second, if the bottom layer is totally dry on the surface, it steals the water very quickly out of the upper layer, and causes the top to dry out too fast. And that can cause lots of cracking.

      I hope that helps. Definitely let me know if you have any other questions and I'd love to see a photo of the finished floor! :)

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    2. Sigi.. we have made some progress in our earthen floor, already laid the top coat and now I was thinking about using a top layer of clay paint, to add some color and level to the height of the wood expantion joint. But I'd maid some test and the clay paint gets full of little tiny cracks. Do you have some tip to avoid that? Otherwise I think the other option is to put a finish level that's like a plaster. But it's more work.
      Hope you can help... Thanks again...!!

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    3. First I want to congratulate you! You've obviously done a lot of work. I hope you are happy with the results! Now for your question... Yes, you can do a clay paint (though you might have more control if you do the thin plaster instead).

      But let's work through how to do the paint... It sounds like your test are crazing (kindof a spiderweb of cracks). If this is the case, it is likely one of two things... Either there is not enough good sand in your clay paint OR you are applying it to a completely dry substrate.

      So easy one first...be sure that you always apply clay paint or plaster onto a damp surface. Otherwise the surface absorbs the water really quickly out of your paint/plaster, and pops the bond. For a floor, I like to soak it the night before, and then again the morning before I'm going to apply a new surface. And you may have to re-wet as you work to be sure the surface is always always damp.

      Then you can work on increasing the amount of sand in your recipe. You can usually go to 50% clay/50% sand with no problem. Do different test mixture with various ratios. The highest clay content that doesn't crack is your best mix to use. Also, make sure your sand is toothy/angular (not rounded). You can tell by taking a pinch between your fingers and rub it very close to your ear. It should be loud!

      Finally, you can add an insurance policy: chopped fiber of some kind. This can be super finely chopped straw, the puffy fibers from cat tails, recycled paper pulped in water, or you can even use wheat paste (though sometimes this can change the color over time). The fiber helps to knit the clay together, preventing shrinkage cracks.

      Not sure if you saw this, but I have more about clay paint here: http://buildnaturally.blogspot.com/2013/03/make-natural-non-toxic-paint-from-clay.html

      Hope this helps! Let me know how it goes.
      Sigi

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    4. Thanks! I'm going to try adding a bit of sand and more fiber, I think that will work... we're still waiting that the leveling layer get's dry (since it's winter here it has taken a lot of time!!) and then we'll apply the finishing layer with the clay paint.
      I will let you know how it works.. thanks again...

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    5. Hello again..! the clay paint worked perfectly! We added some fiber and sand, and no cracks! :)
      We just applied the last layer of linseed oil, the thing is that the owner/builder applied it without any solvent, and now there are some parts of the floor were the oil is almost solid but very sticky... and the floor is uneven .. Do you have some tip to fix it? I don't think is a matter of days to let it dry, because it's already dry.. but saturated. I thought maybe buff it? or add a layer of solvent?
      Please let me know if you have some tip.
      Thanks again!! greetings from Chile!

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    6. Sounds like you have raw linseed oil perhaps. Which has no drying agents and can sometimes stay tacky without hardening. I would use some solvent to try to rub away any excess oil until all surface feel non-tacky. Then use a diluted oil to add another coat (or coats). If indeed you have raw linseed oil (instead of boiled), then do a quick google search for "how to make stand oil from linseed". Basically you will take your raw linseed oil and polyerize it by heating it (carefully!!) for an extended period of time. This can be done in the sun. Hope that helps. And glad your clay paint worked.

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  12. Wow. I really appreciate your detail as we begin our floor. I do have a question for you. We have some septic drain pipes in our adobe floor and the one closest to the surface is only 3 inches below the surface of the floor. We will be insulating our floor and going through the steps you have listed below. Do you recommend any specific prep work around that pipe or can we just go over the top of it? Thanks in advance for your time.

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    1. Hi and thanks for your great question! So here's how I approach this situation in an adobe floor:
      1) make sure that your pipe is seated firmly...no wiggle, no bouncing. --this protects the pipe from potential damage (of fittings loosening) and prevents movement cracks in the floor.
      2) if you have any cold water line, add some pipe insulation around them. --to help prevent moisture buildup around the cold surface
      3) add extra fiber (straw) into your adobe mix around the pipe. --this helps prevent cracking due to uneven thicknesses in the floor where it goes around the pipe (uneven thickness often means uneven drying time, which is what causes the cracking).
      4) you can also trowel some open weave landscaping burlap into the top of your base layer of adobe (while it's still wet). --this adds extra protection from movement and cracking in the thinner floor over the pipe.

      Hope this helps. And have fun making your floor!!
      -Sigi

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  14. Can an Adobe floor be safely cleaned with a steam mop?

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  15. Yes, the adobe floor can handle the steam mop. However, if you use a wax sealer (which really makes the floor lovely), the steam will dissolve the wax and you will have to re-wax after.

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  16. Nice concept of adobe natural floor. But what i wanted to know is whether it takes much time to install or as regular floor installation?

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    1. takes the same amount of time as a concrete floor (only without the carbon footprint)

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  17. Great site. I am working on a new house for my family. It is a modern two story house. The floors are plywood on joist and have a 1.5" chipcrete / gypsum layer that contains the pipes of the radiant heat. Can I just add a leveling and finish layer? The chipcrete floor is already leveled so what thickness would you recommend for the leveling layer.

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    1. theoretically, yes, you could add a 1/4" to 1/2" adobe floor layer on top of your existing radiant layer. It's probably sized & placed for the amount of mass that you currently have on the floor, so unless you know specifically, you probably don't want to add a bunch of mass (ie, too much thickness). Things to remember....
      1) wet the existing surface before you lay your floor
      2) if there are any cracks in the existing substrate, they will come through your clay
      3) test your mix before you commit to the whole floor (so you can be sure to get the perfect ratio of materials)
      4) adding chopped fiber of some kind helps as insurance against cracking
      and most of all...have fun!

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  18. simply superb !.... wud love to hear more from u on earth architecture! will enhance my skills! thanks! wish u best.......

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  19. Can you do earth floors on 2nd levels over structure?

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    1. absolutely! The trick is to stiffen the floor framing, because any flex in the floor will result in cracks.

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  20. I am delighted with your clear desription of the process. I am about to do a floor in a very old house i have_no floors left! I love in outback Australia with clay soil But very alkaline-ph 8-10. My water(from Bore)is also Ph8). will this impact on the floor. Climate is very hot.Even our ground outside develops sink holes in the clay soil during drought(can be feet deep). Many thanks. Faye

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    1. I would first test your soil. If it's pH is 8ish, that is slightly alkaline and definitely not an issue. If it's a higher pH, it would definitely make gardening a challenge, but I'm not sure the effect on the floor, to be completely honest. My guess is that the only issue would be that you couldn't mix the soils with your feet (or you'd be left with alkaline burns on your skin). I know that many people use lime putty as an additive to clay plasters and floors, and that increases the alkalinity with no downfall. The pH wouldn't cause sink holes...that's a geological substrate issue....so as long as you've prepared a good base for the floor, and you are building on solid ground, you won't have sink holes. I would definitely do a test area to start.

      Hope that helps. Sorry I don't have more specific experience with your issue.

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    2. Many thanks. Im going to give it a go. At least with summer just starting there wont be any issues with getting the floor dry!I have replaced a missing wall with straw bale wall -I plan to use my clay to render.Its so much fun doing this house-100 years old, unlived in for 10 years, but has a beautiful story to tell. AND, in australia, if you are renovating at low cost, no need for any permissions from local authorities. It is a nightmare trying to build alternatively from scratch. Quality instructions like yours gives confidence to amateurs like me.!

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    3. Many thanks. Im going to give it a go. At least with summer just starting there wont be any issues with getting the floor dry!I have replaced a missing wall with straw bale wall -I plan to use my clay to render.Its so much fun doing this house-100 years old, unlived in for 10 years, but has a beautiful story to tell. AND, in australia, if you are renovating at low cost, no need for any permissions from local authorities. It is a nightmare trying to build alternatively from scratch. Quality instructions like yours gives confidence to amateurs like me.!

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    4. I'm so glad the information is useful to you! Have fun with your floor and the rest of your project. Sounds like you are doing great work.

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  21. Thank you for the detailed explanation. I was wondering about the durability of an adobe floor. We have two big dogs and two unruly children :), and I have found that even hardwood gets scratched really easily in our house. I don't mind doing touch-ups every 5 years or so, but would not like to have to fix it every year.
    Also, can floor heating pipes be installed in these?

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    Replies
    1. very very durable. Scratch-wise, it's similar to oak if you put a hardening oil sealer on top. You definitely would not repair annually. And yes, absolutely, adobe floors work great with in-floor heating, because they are a mass material, so they absorb the heat very evenly and very efficiently.

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  22. What do you think of adding lime to the mix for the finishing coat ?

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    1. I never do it. There is a secondary chemical reaction that can happen as the lime cures depending on the mineral make-up of the clay. And I personally don't see what the added benefit would be. I do use clay to pigment lime occasionally. And I know people who regularly mix the two for various plasters and such. I would strongly recommend make a test before committing to your whole floor. And seal the test to be sure you can control the finish in whatever way you like. Hope that helps.

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  23. wonderful blog! i am very curious about the oils that we could use, can you suggest any other local oils apart from the above mentioned, like maybe mustard oil, and coconut oil.. or any other vegetable oils?

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    1. It needs to be a hardening oil...that polymerizes when it reacts with oxygen. That's what makes the oil a sealer. Otherwise you will just have a goopy, sticky, surface.

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  24. Great info! I am building custom cedar greenhouses in Colorado with radiant heating/cooling & not able to use concrete (HOA) requirements. The adobe floor is a great option. What is the best waterproofing treatment? Looking at Boiled linseed oil?

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    Replies
    1. any good hardening oil works, really. www.claylin.com has great easy-to-use products.

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  25. Thanks, Keep up the good info! It really help us!

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  26. Thought you might find this interesting! Check out how the radiant heat tubes are drying the greenhouse Adobe floor I'm building for a customer.
    cutting dry time in half! Will send photos to buildnaturally.com

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  27. Thought you might find this interesting! Check out how the radiant heat tubes are drying the greenhouse Adobe floor I'm building for a customer.
    cutting dry time in half! Will send photos to buildnaturally.com

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    Replies
    1. That's definitely an innovative drying solution. Just be careful when creating uneven drying, as this can create unwanted cracks (where none would have developed otherwise).

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  28. Hi Sigi,
    Can you recommend a specific beeswax paste for the final adobe floor finish? Thank you.

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    Replies
    1. My current favorite is Roman's, which you can purchase from www.earthenpigments.com (and they have great customer service to call and get advice on which specific product is best for your application). I also recommend www.claylin.com - they have proprietary oil and wax finishes that are high quality.

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  29. Thanks Sigi! Also wondering if I could still apply a final coat of the clay alis if I've already applied linseed oil?

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    Replies
    1. Not usually, as the clay needs the absorbency of the surface below in order to fully bond. But I would do a test area to see if yours will work. It's possible that if you have very little linseed oil on, the substrate may still be absorbent. And if the test area doesn't work, you could try scratching up the surface a bit and do a second test. Hope that helps! Let me know how it goes.

      (ps. You CAN apply the wax over linseed oil, though.)

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  30. Thanks Sigi, for all your advice! You are like having a "live" book!!! I will let you know how it goes!

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  31. Hi Sigi... how long do we have to wait to apply the next coat of linseed oil.... can we apply it while its drying or do we have to wait for it to completely dry?

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    Replies
    1. wait for it to dry completely. Hardening oils dry by oxidizing, that is, they react with oxygen in the air. Applying additional coats before the previous is dry will slow down the oxidation of the original oil coat (and it may then stay tacky for a very long time or the upper coat may slough off because the lower coat is tacky underneath)

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  32. So, I've had this idea bouncing around in my head for a long time about building myself a house... specifically, an enormous greenhouse hardy for my Zone 3 homeland. We're talking a 60'-radius geodesic dome, that's how large: one big enough to enclose all the land one resourceful person would need in order to feed themself. (I'd want this house to make a point, dontcha know.)

    Obviously, if the goal is to insulate a quarter acre of land from Midwestern winters, every watt and penny saved will go double just by the sheer quantity needed (all the more reason to make it green); so it bears asking: once everything's sealed and cured and dried, would maintaining a high-humidity greenhouse environment on the inside cause any long-term maintenance problems to an adobe floor?

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    Replies
    1. hmmm, I'm not sure I totally understand the concept of what you want to build, but to answer your question about the greenhouse...if it will have a misting system that keeps it humid, then I would recommend a gravel floor or some kind of pavers (brick, stone, etc.) set in a sand bed. That way the ground helps you regulate the moisture inside the greenhouse. If what you mean is that you will have a glass covered structure with plants in it, and you will water those plants (not use a misting system), then an adobe floor would be fine. But I would keep in mind the function of the space, and then choose a flooring material that is appropriate to that function.

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  33. Sorry, you're right, I wasn't very specific. What I want to build is a house with a very large greenhouse room built in. My design is to start with a one-story deep circular basement space and top it with a geodesic dome, to take advantage of the high volume to surface area ratio.

    The house part would then be built to have three floors total: basement level, ground floor, and upper. The ground floor would not cover the whole basement, just the northern 1/2 or so; that half of the basement level would be living space, rooms like in any other house, with windows onto the lowest part of the greenhouse to let light in. The ground floor rooms above the basement would occupy a 1/4 to 1/3 wedge of the northern half, leaving some balconies, the floor above ground, and the southern half of the basement all together in a single, open-plan greenhouse room. I'd plant vines up and down the walls between floors, shade-tolerant leafy greens in the shadow of the southern basement wall, and sun-loving plants like tomatoes or beans in the sunny flat parts. The structure would probably be covered in a plastic like Solawrap, since I've heard that insulates better than glass, and is sturdier.

    I guess, to be clear, I'm some years yet from actually making this, because that is how grad school works; but I'm also completely committed to the idea, and I will likely build some updated version of this as my first home. Though part of the point would be to show how low-impact a person can live, if they choose to, the other part of me wants to try growing some tropical fruits as well, to show that living green can be a luxury. That's why I'd asked about the humidity; I've done just enough woodworking and pottery to know that home construction is neither of those things.

    I like the idea of pavers and sand for the lower greenhouse levels. I've read that humid air is less dense than dry air, so maybe it'd work to build adobe floors for the basement living spaces and keep the tropical plants away on the upper levels... or maybe that's something I can't know until later. Anyway, thanks!

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  34. Hi, I already have a concrete slab. On top of it, I need to install plumbing and electricity. I want to finish with floor heating and Adobe floor. I can't put insulation plates on top of concrete because plumbing is in the way. Can I level with cob and then put insulation on top of it followed by heading + adobe floor? Or do you have other suggestions on how to insulate over plumbing?

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    1. well, kindof depends if there is a good capillary break and vapor barrier below your slab. If either one is missing, then your slab will be persistently damp...in which case I wouldn't recommend clay in contact with the concrete and I definitely wouldn't recommend putting your electrical in contact with the slab...

      In terms of insulating above a slab, it would usually go right on top of the concrete, then if you are running any systems, they could go on top of the insulation or could be routed into channels from the top of the insulation.

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  35. Hi.I am considering earthen floor in our future house (In Israel..) and wanted to ask if it is possible to wash the floor - actually pouring water and wiping off. And also how visible are stains on the floor? (food,oil etc.)
    Thanks for your wonderfull articles you are a true inspiration to me :)

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    1. yes, absolutely, you can wash the floor...just like you would wash any wood floor

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    2. ps. so glad to hear you find inspiration here! :)

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  36. Hi I have a completely old and very dry adobe floor in a old adobe house and wondered what to do regards this. I have about 3 cm to gain to bring this floor level.Really looking for ideas as I like the properties of a adobe floor also the temperatures here in Hungary fluctuate from very warm to very cold in winter.This will be my bedroom/bathroom.Thanks for your time.

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  37. Is it possible to set floor tiles into an earthen floor. I plan on doing a lot or fibre dying in my utility room. I am putting earthen floors in the rest of my downstairs and got some 12"x24" porcelain floor tiles off craigslist that are perfect for my utility room. I was told I would need to put a concrete pad down over my radiant heating pex tubing and then install the tiles. I am just wondering if I could seat them into the second layer of earthen floor instead. Would they stay put or need some other kind of adhesion method. Then I could linseed oil finish instead of grout.

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    1. absolutely! As long as the tiles are textured on the bottom (normally they are), then you can set them in the final layer of the floor and use the adobe mixture as "grout" between. Linseed oil after the clay has all dried fully to harden. :)

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    2. wow thanks for your prompt reply Sigi. I appreciate your advice.

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  38. I live in Chiapas, Mexico in a hot humid climate. We are building a fitness center out of mainly natural materials: it has a thatched "palapa" roof, the workout equipment is mostly made of local woods, but now the time has come to put in the floor. The floor will get hard use, with weights being put on it, dancing and a lot of rough physical activity. Would an earth floor work instead of a concrete one? If so, what recommendation would you make so that it be as durable as possible?

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    Replies
    1. Hmmm...that might be a bit much for an earthen floor. The people activity is not really a problem, since I doubt they workout in heels. But the equipment could be rough on the floor, particularly if it is heavy and may get dragged around across the floor. I'm wondering if you could make pads for the equipment and then use adobe floors where people will be working out. (dancing and jumping around on the adobe floor will be much kinder to bones & joints than concrete would be). You could harden the floor with multiple coats of hardening oil, such as linseed.

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    2. We can place the equipment in one place semi permanently, and we can be careful to lift it when it needs to be moved. You have a good point about the earthen floor being kinder on bones and joints. Living in a small town in southern Mexico as we do there is no store like a Home Depot where I can get things like linseed oil. Is there anything else that can be used to harden the floor?

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    3. sounds like a great plan! For the hardening oil, there are other types besides linseed oil. Basically any oil that turns into a resin when it oxidizes. Here is a wiki article explaining more: https://en.wikipedia.org/wiki/Drying_oil

      You could also heat beeswax, thin it, and work that into the floor, but that will need to be reapplied on a regular basis. Not sure that is the most durable option for your applications...

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    4. Thank you for your replies and the wiki article. I'm sure I can find some type of hardening oil. Considering the heavy use the floor the floor will receive and my unwillingness to have to put in a new floor anytime soon since we are doing all the work, does adding any cement to the sand/clay mixture make it sturdier, or even work?

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    5. don't add cement to your clay mixture. That gives you the weakest of both worlds :(

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    6. Okay. How about structural support like rebar or wire mesh inside the earthen floor, does that do any good? I've never seen an earthen floor but like the idea, just want to make sure it'll hold up to 100 people a day doing exercise.

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    7. no, don't put rebar or metal reinforcing into an adobe floor. They are not compatible. You want to use some kind of fiber, such as straw. That acts as your tensile reinforcing (the same way rebar works in concrete). It doesn't increase compressive strength, however. For that you want to be sure that your floor mixture has larger stones (aggregate) as well as good coarse sand (the same as concrete)

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  39. Straw is your rebar in earthen floors.

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  40. I live in a part of the world where product variety is limited. There is hay here, but no straw, does it matter?

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    Replies
    1. for sure, hay is great! Any type of fiber that is available locally will work. Doesn't have to be straw.

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  41. Hi Sigi, I am back on your website AGAIN!!! Best place on the internet :-) I have a question on using rigid foam for insulation please? I am going to be installing an adobe floor over a concrete slab. So after adding a layer of builders plastic (there is already plastic underneath the slab - I just want the extra as insurance) I put the rigid foam insulation sheets down - but there will be movement in those, won't there? How exactly should it be attached to the concrete to prevent movement, please?

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    Replies
    1. Great question! So you can tack glue the insulation to the concrete. Or you can fit it so tightly that it doesn't move. Those would probably be my 2 top choices.

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  42. Hi. Love your work! Have a question... I live in an apartment building in first floor and would like to naturalize our home. I was wondering... can I pour earthen floors over tiles? I would like to avoid tearing the tiles out (if possible).
    Nina

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    Replies
    1. Hi Nina, I wouldn't recommend that. Two things... First, the earthen floor is heavy, so you'd need to know that the floor structure can handle the extra weight. You also need to be sure that there is no flex in the floor substrate. (Any flexing will crack the clay floor.) Second the thickness of the floor may require substantial adjustments inside...lifting kitchen cabinets, resizing door frames, etc.

      Instead, I would explore adding clay plasters or paints to your walls.

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  43. Would I be able to modify an Adobe floor so that I could use it around a blacksmith's forge

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    1. what are your performance requirements for the floor area around the forge?

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  44. This comment has been removed by the author.

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  45. Thanks for this great tutorial! Very useful info. I've built a small strawbale shed that I use for storing yard tools, lawnmower, etc. I've yet to put a finish floor inside, right now it's just natural ground.
    Would a earthen floor be appropriate for an application such as this? Obviously it would be getting lots of traffic and potentially lots of scratches from tools and equipment. I've always wanted to try earthen floors but I worry about durability in high traffic environment. Thanks!

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    1. I built a shed for my parents with an earthen floor and it has held up well for over a decade, with lawnmower in & out, shovels, snow blower, etc etc etc.

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  46. How do you attach a bottom plate for an interior wall to the adobe?

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    1. install the interior walls first, then float the floor to the walls. Or, you can wait until the floor dries completely and then use masonry fasteners to attach the plates.

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  47. Hello Sigi and thank you so much for your elegantly clear and practical guidelines. I am 40 years a painter and plasterer who loves to make limewash and mess around with "primitive" finishes. At the moment my lady and I are joyfully embarking on a 2-storey, straw bale round building down by the creek. We're planning an earthen floor and we want to install radiant heating pipes connected to a wetback on the wood stove. We have oodles of river stone to use as a foundation; then builders polythene and a layer of foam insulation board. Are the PEX heating tubes simply embedded near the bottom of the base layer of adobe, or do they need to be securely pinned down, and if so,to what? And is there any danger of the heated tubing causing uneven drying and potential cracking? Would you alter the base layer recipe to allow for this? We're also going to embed a wall-to-wall (Celtic endless knot) timber and brass inlay into the floor. I can't imagine that the 25mm deep inlay will ever want to lift or move, any more than a floor tile would. Would you think it necessary to secure it beyond that? I appreciate your care and the time you give to answer everyone's questions.

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    1. Hi, you just need to be sure that the PEX tubes will stay where you laid them as you set the floor. Often that means tying them down to whatever is below...in your case, the insulation. This can be done with zip ties or U-shaped metal pins, or any way that you can secure the tubing enough to keep it from moving around. The tubes won't really lift, but they may want to move laterally as you install the adobe around them.

      In terms of drying, you will want to let the floor dry naturally to avoid cracking. If you need to speed it up, you can run very very low heat through the tubing. But uneven drying will, yes, create a risk of cracking.

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  48. Hello most helpful and appreciated natural building person on the internet! I wanted to ask about making adobe floor tiles/slabs? I was going to be doing a 20' X 30' adobe floor over a concrete slab, but the work involved will be far too much for me to do each part of the floor in one go. So, I was thinking about making a few 4" thick stones/tiles each day and stockpiling. Then I can lay them all at once. There will be insulation board installed over the concrete first.

    Would that work OK do you think? I think there would be a need to add a thinner layer of the clay mix over the top to seal and help hold everything together? Any suggestions and comments would be most appreciated.

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    Replies
    1. yes, you could do this. You can "grout" with the same adobe mixture. Note that you will see the individual bricks/tiles. Also, if you have any cracks in your slab, they will transfer through the adobe above, so be sure you have a good solid base. Finally, I would make your bricks/tiles a bit thinner than you want the finish floor and then set them with a clay mastic...same way you would set tiles. let me know how it goes!

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  49. Your tips are amazing,especially the layers.

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  50. Hi Sigi,
    All this posted information is appreciated :) I do have a question for you... I am planning a 12 across geo dome here in lithuania. The ground is about 15 or so meters of Clay straight down. i am planning on installing rigid insulation around the perimeter on the exterior for about a meter outwards from the structure and then putting an earthen burm around to try and insulate the ground more around the pole foundation. Do you think the method described above would work with the deep clay ground we have here?
    Thank you
    Tonino

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    Replies
    1. I don't use this method of insulating out from the foundation, so you would want to ask this question of someone that uses it regularly. I like tried-and-true when it comes to the part of the building that keeps it all together and stable. :)

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  51. Hi Sigi, thanks for your information. My partner and I have just finished our cob floor in our strawbale house. We followed your method of oiling with linseed oil and turps rich to lean as suggested (5 coats). Just wondering how long you think it may take to cure? It has been 6 days and still scratches easily. We used approx 200l of linseed oil for 75 sqm. I would appreciate any insight you have. Many thanks Lani

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    Replies
    1. was the floor completely dry before oiling? And did you let each coat cure before putting the next coat on? Also, an adobe floor without any oil should be tough to scratch...so I'm wondering what your process & recipe were?

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  52. In the base layers we had a lot of cracking, so we increased the sand content as we went to reduce it.The whole installation being about 70mm.The final layer was made up of 3 parts clay to 7 parts sand and was only about 10mm thick. Even so there was still a few cracks in the final layer which we patched with the same mix.
    I am confident that the final layer was dry, we left it for one week during which we had several days above 30 degrees C. We put the oil on in sucessive coats, waiting for one to absorb before appling the next.

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    1. Hmmmm...so it's possible that your floor wasn't dry completely. It takes weeks (sometimes over a month) to dry out. If in fact there is residual moisture below, then it may be preventing your oil from curing. If the oil is completely tack-free, then it should be hard on the surface. I'm not really sure what else in the process may be causing an issue. It sounds like you did not add straw to your mix, for example. The straw can help to eliminate cracking and still keep your mix clay-rich enough for a strong floor. This one may be too difficult to trouble shoot online. You might need someone to come and look at it in person to help you figure out what's up.

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  53. We did add straw to all layers excluding the top one. The first layer was the thickest and was left to dry for 3 months or longer, subsequent layers less time as they were thinner and we were in our Summer (low to high 30 degree C).We started in June of last year.
    Do you think we have added enough oil? It never reached the tacky stage, but 200L seemed like a lot of oil. Thanks for your thoughts.

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    Replies
    1. should be enough oil, but again, this is a difficult one to make clear recommendations on without seeing/feeling your floor. Is there someone local & knowledgeable that can come and look at it?

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  54. We've build a straw bale/adobe house and we currently have adobe blocks for flooring (we had lots of extras, so that became our base layer). Now we want to finish the floor. Do you think we could do just a 1/4" leveling layer and then an alis finish? I assume we also need to wet the floor to get a good connection to the adobe and the leveling layer.

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  55. Hey there!
    Thanks so much for a great write up!!!! So awesome to see people willing to offer their expertise to us DIY-ers. Much appreciated!

    I have a question for you regarding the build up.
    I have been doing a lot of research and found that people are using well compacted road crush instead of a cob "slab" and that this could perform better in cooler/wetter climates like we have here in BC. Also it requires no drying time which would allow us to make more progress on our earthship this summer!!!!

    My question is: Have you used road crush before instead of a cob "slab" and what was your experience with it?
    If you haven't used it before is there a reason and how would you feel about using it?

    Thanks so much for taking the time to help us out with this question.

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    1. Hi, and glad this is useful to you. I don't ever use road base, so I can't speak from specific experience. But I would caution you on 2 things. 1) Be sure there are no fines in whatever you use. These reduce (and sometimes eliminate) the capillary effect that the gravel base is supposed to perform. And 2) there is no reason that road base will perform better thermally...so double check the source of your research on that front.

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  56. Hi Sigi, thanks so much for sharing your knowledge. My question regarding Adobe floors, is it absolutely important to have the stones or sand capillary layer? Can i lay my vapor barrier and insulating layer straight down over my hard base, which is still higher than the external ground level?

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    1. to me, yes, it is absolutely necessary. Why go through all that work and skip the step that keeps water out? I'd rather spend a little extra time up front and not have a problem or repair on my hands. And I would use coarse gravel as the base.

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  57. I have only two options for the capillary level, beach stones or bottles both options are very laborious and may only be collected in increments, where i am building is very remote and most of the materials are sourced from on site. Why should coarse gravel be used.

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  58. Hi Sigi
    I have just done the four coats of boiled linseed oil as described above, with the thinners added to coats 2-4. If I wanted to add other coats at a later date to harden it even further, is it okay to wait 6-8 weeks before doing so
    I understand I need to leave it for seven days to cure before walking on it. Then I have some work to do to complete the upstairs of my house and I plan on moving in for the middle of august as my family are coming from England to visit me.
    So I was thinking I could wait until they have gone home in mid s
    September and perhaps add more coats of oil and thinner then.
    Is this a recommended practice or should I just go straight to wax.
    Question 2
    Also I read somewhere that once you add a wax layer you need to leave it another week before walking on it. Is this correct if I plan to use beeswax and buff it.
    Thank you

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    Replies
    1. absolutely, you can wait as long as you like between coats of linseed oil. Just wait to wax until you are done with all of your coats.

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  59. thank you so much Sigi. My page on facebook is Pamscobhouse if you are interested in seeing my floor. :-)

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  60. Hi Sigi. We've done a dirt floor in the Karoo (South Africa) in a very small dry-packed stone hut. The floor was done out of clay, sand and lime and it needs a sealant. I would guess your process for sealing a dirt/clay floor will be fine? In other words using linseed and turpentine. Looking forward to your reply!

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  61. hmmm...so I never use lime in my clay mixtures so I'm not 100% sure what type of sealer to recommend. You could try a test area with linseed oil to see if you get the results you are looking for. You could also try a wax finish, which for sure can be used on either clay or lime surfaces. Hope that helps! Best of luck.

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  62. Hi Sigi, I love to get your advise. I have completed a new modern passive solar house. We have a clay floor, about 2" thick mostly sand, straw clay mix with a gray linseed oil finish. The floor sits on top of a floor heating system embedded into a 2" chipcrete pour. We are super happy with the floor. However our clay contractor failed to finish the floor nicely due to circumstances beyond her control. So I am now pondering to redo the top-finish of the floor. One idea we consider: Can we use a wood floor sander (band or cicular) or stripper to remove the top-finish and refinish it? Our top-finish consists of oil and clay and grey pigments (it very much reminds me of oil paint). Is it better to take the top-finish completely out or just the minimal amount to get rid of the discoloring and "orange peel" and then refinish by applying a new top on the existing.

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    1. Gosh, it's tough to make a recommendation on this without seeing exactly what the issue is that you are trying to resolve. I'm not sure if a floor sander would work. Perhaps if you are just trying to remove a finish (ie, not the actual clay), then a light sanding or buffing would work. I'd do a test area by hand before committing to the whole floor though.

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  63. hi, do you have any experience with using olive oil or an other kind of vegetable oil?We prefer to use local materials for our earthship in portugal. Would it work on a cobfloor? thank you! helena

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    1. it must be a hardening oil...one that polymerizes at room temperature with exposure to oxygen. Olive oil is not a hardening oil, so it will always just stay sticky and wet.

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  64. hi sigi. wouldn't you recommend an inch or two of sand between the gravel/hardcore Base and the vapour barrier? that's what I've always seen done for concrete floors, to prevent the plastic sheet being punctured by any sharp stone edges...

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    1. You can. I've done it both ways. The plastic is really buff, so I've never had a tear. But if you were worried, you could certainly do the sand.

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  65. Hello Sigi, you have an incredible amount of knowledge, thanlk you for sharing it!
    I am trying to make this kind of floor in Poland, which is literally untouched by the concept. I have a question about solvent - the only one I can get is 98% orange terpen with 1% cleaning agent (nobody uses that here for thinning, just for cleaning) and it's 25$ per liter. Should I use it as is (or rather not use it, as I don't have the money) or thin it with water before thinning the oil?

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    1. Oh, and I know that the impact of the cleaning agent remains a mystery....

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    2. Gosh, I'm not sure. It sounds like that's a d-limonene solvent, which does work well. But I can't be 100% sure. I would recommend to do a test to be sure. I would not thin with water as you would then need a surfactant in order to get the oil and solvent to mix...which kindof defeats the purpose... Hope that helps. Would be great if it works!

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  66. Hi Sigi..
    Writing from Chile again.. Now I'm building my own house and we're making the adobe floor in the bedrooms. We went with a final layer like plaster, and it looks really great. Now we have to seal it, and I was wondering if it wouldn't be better to start with the more thinned layers (40% solvent) and then apply the thicker layers after, so it absorbs better.
    Please tell me what you think..

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    1. According to my go-to guru on earthen floors, Sukita Reay Crimmel, the simplest solution is to apply all of the hardening oil at once, in several passes right after each other. She uses a slightly diluted solution (I believe 25% solvent). Each additional layer of oil is added as soon as you finish the previous layer...you just keep going over the floor until it reaches maximum saturation. I've done it once this way and indeed it did work really well and was much simpler.

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    2. Sounds much easier..! we'll do it that way..
      thanks again for always being so helpfull!!

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    3. Anytime! :)
      Let me know how it goes

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