[GSBN] earthen floors

[Chris Magwood]

We've built three earthen floors in a canuck climate, and they've all 
worked quite well.

By far the best was the one where we used compressed earth blocks laid 
on a sand bed as the earthen base (no drying time required) and then put 
a fairly thin (1 1/2 inch) earthen floor mix on top (a lot like our 
earthen plaster mix). Drying time was no problem with such a thin pour, 
and three coats of oil did the trick. This floor was even subjected to a 
flood when a cooler full of melted ice broke and wasn't discovered until 
the next day. It got mopped up and the floor was just fine... couldn't 
tell it had sat under an inch of water for 12 hours.

The question of how to insulated under a floor in our climate seems the 
same whether it's for a concrete slab or an earthen floor. The go-to 
material would be foam... yuck. We've also used RockBoard from Roxul, 
which has enough compressive strength for a floor system, but not to 
bear foundation/wall/roof weight. The floor described above used an 
experimental floor with vapour barrier, four layers of used carpet and 
12 inches of dry sand under the earthblocks. The energy performance of 
this building has been excellent, outperforming the computer modelling 
that was done by a significant amount. It's a public building too, so 
there hasn't been an over-conservative owner keeping the heat low or 
working to reduce energy use.

I'm really keen to try some actual testing of both used carpet and sand 
beds. I know that there are R-values assigned to both materials, but 
some in situ testing would be interesting. My "tootsie test" of sand 
beds on a beach on a hot summer day tells me that even in baking hot sun 
the heat is only on the top inch or so, and the sand is nice and cool 
just below the surface.

Maybe a science guy out there can tell me why a deep, dry sand bed is a 
dumb idea, or a good idea...

Chris

On 12-01-06 4:10 PM, Frank Tettemer wrote:
> I have a True Confession ...
> Over the years, I have designed and built way too many concrete floors.
> They've had trowelled-in pigmentation, been sealed and waxed with Eco 
> House products, (or Bioshields products), and they've looked beautiful.
>
> But I would much prefer the touch and leather-like feel of a 
> well-built earthen floor.  And I truly believe that the embodied 
> energy in a concrete floor will make them less affordable, maybe even 
> impossible to build, in a couple generations.  Or sooner?
>
> There's one thing that gets in my way:
>
> I don't know how to insulate to an R-25 or R-30 level under an earthen 
> floor.  Which I truly believe to be the Minimum R-value for our 
> northern climate, for a slab-on-grade.  Anything less, feels cold. And 
> seems energy-lax.  Every earthen floor in our climate that I know of, 
> has had something which has caused the owners to rip them up, and 
> change 'em, in less than just a few years.  Every one!
> (Is this a Canuck Conundrum?)
> Surely there's a way to do it?
>
> Eagerly awaiting the possibilities,
> Frank Tettemer
>
> ................................................................................................................................................................................................. 
>
> John "Rebar Baron" Swearingen wrote:
> Every time I'm feeling a bit ill, the first thing I'll do is lay out 
> on a concrete slab. It seems to have mystical healing qualities, 
> because no matter how bad I feel, I get right up almost as soon as 
> I've laid down!
>
> .................................................................................................................................................................................................. 
>
> Bob Theiswrote:
> It's equivalent to the point of the work and complexity of a parquet 
> floor; the wood patterns delight the eye, and an earthen floor 
> delights the feet.
>
> we like the stuff beneath our feet to be resilient. Concrete is not. 
> Earth floors are that, but something more. What could feel more 
> natural than earth beneath your feet? Simple as that.
>
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