[GSBN] earth floor odds and ends

[Bill Steen]

On Jan 5, 2012, at 6:31 PM, RT wrote:

Actually he wrote a whole lot of things that I will try to keep short.  And given the nature of my response to Rob Tom's comments, I'll change the thread to that of earth floor generalities.
And thanks Bruce for waking us up.  Just for clarity what I've written is not in defense of earthen floors nor in the interest of promoting them, but rather one of clearing up what I would consider to be misconceptions.

The first of Rob's comments had to deal with soil borne illnesses.  Without research I suspect the list is long.  In our part of the world, one of the most common is Valley Fever that results from fungal particles in the soil.  Come through the lungs via respiration.  Don't know a whole lot more about others, but I suspect that moisture and poor hygiene would have a lot to do with the hookworms.  As we all know moisture is often the culprit in many problematic situations, in this circle, one of the main causes of insect infestations in straw bale walls - as often pointed out by the illustrious Robbie Tom.
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> Me ? Despite Beel's best efforts, I never really became a big fan of earthen floors for my locale.

God forbid, you would be the last guy I would try to convince on anything, much less make a fan out of.  Hah!  But I will pay you a compliment in saying that from all the lists that I've been a part of with you, I've learned a whole hell of a lot.  Initially I was trying to address the need for concrete, but since he has widened the discussion below, I'll take the bait and go with it.  He's good at that.
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> One :
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> Earthen floors make a lot of sense in places the climate is such that earth-coupling is a reasonable proposition. That is not the case in most, if not all of Canada.
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> In order to use an earthen floor in this climate, it would be necessary to de-couple it from the earth with at least R-20 worth of insulation (assuming that the floor is at or near grade)
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> It would also be necessary to provide an effective strategy to prevent soil-gas intrusion into the indoor air environment, something that is less of a concern in climates where air-tight construction/super-insulation is not essential.
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> The above almost relegate earthen floors to being not much more than a cosmetic veneer to provide a pastiche of "natural" earth-connectedness.

I will take advantage of Robbie's comments to clarify a few things here, certainly I would not try to argue with the guy.
Any floors that we've been involved with have been de-coupled from the earth at least as far as I understand the concept and the term.
Typically we install a substrate that drains moisture/water away from the floor, most often stone/gravel.  No objection here to a poly liner if needed or whatever.
Insulation we always use.
Soil-gas?  Never had to deal with it, but I would assume that one would incorporate the same measures that one would with a concrete slab.
So therefore we are talking about something more than a veneer.

When it comes to earth coupled floors in the traditional sense, I have more experience with them than the average person.  I frequent a little adobe home in northern Mexico where a couple in their 70s live.  The house is immaculate, the floors, by their choice, but by poverty is only lightly compacted dirt that is maintained by sprinkling with water and sweeping.  Perhaps a little addition of dirt every now and then.  It's a lovely experience, the little bit of moisture on the floor creates fabulous ambiance during the hot summer.  And of course, this is a context specific application that would be of little use in Ontario.  I'm sure they don't have hookworms either.  In essence, what I want to say is that the variables are many in this case and generalizing doesn't yield much in the way of useful information.
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> Two:
> I was stunned by the volume of oil that Beel told me was needed to adequately "condition" soil mixes to rendered them serviceable as finished surfaces (by Auntie Septic's North American standards of performance).  I remember my Mom telling me that back in Olde China where human labour was cheap, the floor guys simply pounded the $#!+ out of the earth to compact it and called it a floor.

Thinking back, I suspect that my comments may have been somewhat exaggerated, most likely to irritate old Robbie.  I've thought a great deal about the oils and earthen floors these days and am re-thinking a lot of earlier assumptions.  Only thing I'm missing or lacking is a whole bunch of testing, but at the moment I'm having much more fun in Mexico, that place where most are terrified to go these days.  However, I did coax Greg McMillan, one of CA's original straw bale souls down there last month.  But back to oils for the moment.  As for the amount, instead of progressively thinned application of linseed oil, it may well be that one full strength coat may be sufficient in most applications.  Or a tad bit more.  As for the type of oil, we've never used or promoted chemical laden boiled linseed oil, I think we've beat that discussion to death by now.  However, some pretty loose testing on my part suggests that almost any average grade cooking oil may be good enough for a lot of applications.  For now, we can avoid any discussion about the downside of GMO modified corn oil.  Let's just say there are options.

As far as Robbie's mom and pounded floor, it's quite true, but there are often subtle variations.  The kind of floor he describes is common all over the world.  The one I described in Mexico is that way, but clearly not suited for most modern houses.  In Japan, such a floor is referred to as a "Tataki" floor, which essentially means "pounded"   The trick with making those floors work however, is the addition of a small amount of lime and "nigari" or "magnesium chloride" that is commonly a by-product of salt production and a key ingredient in the making of tofu.
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> I found Beel's revelation to be disturbing given the horror stories about woodworkers' linseed-oil-soaked finishing rags spontaneously combusting ... not to mention the potential for long-term pollution of interiors due to the plentiful VOCs  that such large volumes of oil would necessarily generate. Again, not so much of an issue in warmer climes where high air change rates would be okay.

Again, I think like traditional earth floors, we've pounded this sufficiently.  We've always used raw linseed oil that we sun-thicken so it dries more quickly.  As far as I have been able to detect, msds sheets included, conversations with producers, that oil contains no voc compounds.  I'm certainly open to the possibility that I've missed something in my investigations, perhaps, but it's not obvious at first glance.  I can tell you one thing, boiled linseed oil has very offensive odors, raw linseed oil nothing I can detect, doesn't smell much different than food-grade flaxseed oil in the health food stores.  Probably the significant difference between the two would be whether or not the oil is organically produced and the method which is used.  I will admit that citrus thinner that we've used for a while has in recent years become suspect and isn't always considered as desirable as once thought.  I will say though that in floors that we've been a part of, lingering odors have never been a problem.
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> Three:
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> Drying of the oil treatment. I've found that when treating timbers with linseed oil, it is best done during the heat of summer with the timbers outside in full sun and exposed to breezes. To do otherwise either results in insufficient depth of penetration of oil (ie not enough oil applied to do much good) ... or incomplete polymerisation of the oil resulting in a surface that remains tacky and prone to bleeding for a long, long time ... and over that period, being a magnet for air-borne crud and subsequent microbial activity within the accumulated crud -- not the stuff of healthy interiors, besides looking like hell.

Agreed, that is why we've always recommend applying to the oil to floors that are sufficiently warm and with oil that has been warmed.
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> But one then wonders, why not forget about trying to make the earthen floor a finished surface  and thereby forego all of the sometimes-nasty stabilisers and simply use the earthen floor as a substrate for a baked-hard earthen mix (ie clay tile) or stone ?

First of all we've always recommended earthen floor substrates for the finished earthen floor surface that we are really discussing here.  In our efforts over the years, especially in Mexico we've tried just about everything imaginable over earthen mix substrates.  As I pointed out yesterday, broken-up pieces of concrete slabs of various thicknesses we've used. Clay tiles, we haven't but I know they'd work and have been used traditionally that way forever.   I live on baked clay tiles and love them.  We've done very thin concrete pours over well-compacted earth, have performed admirably without the usual 3 inch or more thickness.  We've made the equivalent of clay tiles out of cement and sand - worked quite well.  Stone when available.  And just for those playing around in Haiti and elsewhere, we've never done them in low-cost housing for people of little resources mainly because we thought it an inappropriate choice mostly due to durability issues.

But perhaps the most significant thing I want to say other than to dispel some of the myths above is that I'm certainly not taking the position of promoting these kinds of floors.  I think that there is a place for them and for people who appreciate them for what they are.  We can discuss the technical aspects forever, but I think there is another side to this discussion which is mostly intangible.  There is a different quality to clay that makes it distinct from concrete, plastics and the like.  I'm not against concrete, rather in favor of sensible use of it.  Clay has a very different feel and energy to it.  Let me take one example to illustrate this.  Recently we were called to Ft Huachuca, the military base near us to consult on building some adobe buildings.  They wanted to do research on them and needed them similar to those built in Afghanistan.  The reason was that the technology they had developed which allowed them to see through any kinds of walls - concrete, cement stabilized earthen mixes, wood, what-have-you, could not see through adobe or earthen walls.   Now you can do what you want with that observation, but it does point out a significant difference.  Me?  I'll take it down the mystical road if you like.

The other thought I leave you with is from my Native American mother-in-law (architect mind you), who several years ago built an insulated adobe home in northern New Mexico.  After having grown-up on earth floors in Santa Clara Pueblo and in a passive solar adobe in Santa Fe, she decided to go with concrete in her new home.  She loves the house, it's beautiful and tasteful, written up in my blog, New Mexico magazine and Lloyd Kahn's new book "Tiny Homes."    There is one thing that she regrets with her new home and that is the concrete floor.  From her perspective (subjective mind you) is that the concrete is much harder on her feet and legs and in general, more uncomfortable.  I realize this is a subjective area, but I would also argue that there is a significant difference between the two.  

And that's way more than enough, for me, that's about a year's worth on this list.  Back to translating a Mexican cookbook.


Bill Steen
bill at caneloproject.com
www.caneloproject.com
www.caneloproject.com/blog
HC1 Box 324
Elgin, AZ85611






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