THE JOYS OF A MUD FLOOR
Look at a MUD FLOOR FARM HOME. You think you're looking down at CORDOBAN LEATHER. Throw your mops away. This floor is MADE of DIRT so a little dirt doesn't HURT it! This I learned from the Homesteaders list when a lister asked The resident Yoda, Master of the Universe, Tiv, a question.
Q: you obviously like earthen floors. Could you elaborate a little? Why do you like them better than other types of flooring?
Tvoivozhd: The only cheaper floor is wall-to-wall carpet over polyethylene sheet over sand over polyethylene sheet vapor barrier. I hate unsanitary, uncleanable offgassing carpeting.
My introduction to earth floors was in a friend's house in Jamshedpur, India. His brother built and ran the biggest steelmill in the British Empire---he could afford anything he wanted. What he wanted and what he got was a gorgeous, wide-walled adobe house with beautiful dirt floors, and filled with a couple hundred thousand dollars of furniture.
I was fascinated by the appearance of the floor---the look and feel of Cordovan leather. Asked him what it was. He said dirt mixed with goat urine and several coats of linseed oil.applied as finish coat. It probably had some lime in it---he didn't know.
Earth floors are the next cheapest to the carpeting which I despise. They are good at transmitting heat (or coolth) wear well and are easily repaired or replaced. One exception would probably be high heels---too small an area for a person's weight to produce a reasonable loading.
Earth floors do not crack or powder. John Swearingen, "Skilful Means Builders", is one of the best
contractors in the U.S. Here's his account of one version of earth floors. http://www.snowcrest.net/smb/mudfloors.htm
Athena and Bill Steen are the foremost U.S. experts on earth floors. Buy their booklet "Earthen Floors" for $10 (including shipping) E-mail for purchase details at <email@example.com> or their Canelo website has order forms (and a lot of stuff on strawbale)
I vaguely remember an article on earth floors in Fine Homebuilding in the last year or two, but the issue I was looking for is hiding in one of the many piles that resist close inspection..
An article on earth floors in Designer/Builder, a Journal of Human Environment (August 1997) Article, "How to make a mud floor"---shows one of Steen jobs.
Read about the Monk floor here
(opinion of Monk floor)
Another Swearingen comment
(Shelter, 1973, page 46)
Not germane to dirt floors, but here's a URL on stamped concrete
floors---mostly for information, it's UK.
A Warm and Elegant Solution
Adobe floors, made from poured and trowelled mud, are softer and warmer to the touch than
tile or cement, and carry the rich colors of natural earth. Skillful Means has been
experimenting with various additives to make adobe floors easy create and maintain. One
additive is made from phsyllium hulls, a common ingredient in natural laxatives and
erosion control formulas. This additive makes the mud easy to work and acts as a binder
when the floor dries, reducing cracking and increasing strength. Following is a
description of a recent installation.
U.C. Berkeley Architecture Students Mix Mud in Mendocino
Procedure for Stabilized Adobe Floor
Original plans did not call for an adobe floor. A 4" rough slab
had been poured. We laid 3/4" o.d. radiant heating tubes over
2" insulation on top of the slab, and poured a very rough pea
gravel mix over the tops of the tubs. Our first layer of adobe
with phylum was placed on top of this.
The soil was taken from nearby and contained approximately 30%
clay, silt and fine sand. Preliminary tests with Portland
cement mixtures showed that this soil was moderately expansive,
but mixed with sand could be prevented from cracking.
Base coat of stabilized adobe:
We mixed adobe with 50% sand and approx. 6oz/cf of psyllium in
a stucco mixer. The ingredients were mixed dry to incorporate
the Psyllium uniformly, then water was added. We experimented
with the amount of water in the mix and finally settled on a
relatively wet mix, about the consistency of pancake batter. We
were laying down a thickness of about one-inch. Thicker mixes,
although they would shrink less, could not in practice be
consolidated sufficiently for folds, joints and slip layers in
the mix to melt together--the thick mix resulted in "stretch
mark" cracks resulting from the unconsolidated material which
had been troweled together but which ruptured because of
internal layering. If the mix was too thin, it could not be
trowelled without leaving gross trowel marks--and the wait for
it to dry out was too great. Just the right mix could be
jiggled and pressed into a monolithic whole and still could be
trowelled relatively smooth before moving to the next section.
All of these mixes resulted in shrinkage cracks, which we now
know could have been avoided by increasing the proportion of
sand in the mix.
For a topping coat we used the same soil, sifted through window
screen and mixed with very fine sand (120 grit). Before putting
down the topping coat, we filled the cracks in the base coat
with the same ingredients in a stiff mix worked into the cracks
with a grout float. The surface of the adobe base was scrubbed
with water and an abrasive "scrubby" to clean and soften the
adobe. This process resulted in the cracks filling at least
part way with water, and the cracks drying with dips about 1/8"
to 3/16" below the base surface. This dipping contributed to
the cracks telegraphing through to the topping coat.
The filling was thoroughly dried before the topping coat was
applied. Because the mud had gotten wet during storms, we could
not mix it with psyllium without globs being created. We took
1/3 bucket of dry psyllium and mixed it with about 1-1/3
buckets of water to make a Jell-O-like slime. The very
thoroughly mixed the water into the psyllium, and then allowed
the gook to sit for at least 24 hours. This waiting period
allows water to soak into all the dry psyllium.
Our topping mixture was made by scooping 2 parts mud to 4 parts
sand to 1 part slime, put into the bucket to mix in that order.
Water was added, and we first mixed the sand and the slime
together on the top before plunging the paddle (we used an "x"
shaped paddle on a right-angle drill) deeper to bring up the
mud. The gritty quality of the sand seems to break up the slime
better---mixing immediately with the soil resulted in small
globs of unmixed slime remaining in the mix. The bucket was
very thoroughly mixed to destroy these globs, which show in the
Our procedure in applying the topping coat was to first scrub
and wet the base coat, then trowel the adobe in place about
1/4" thick on average and flatten it with an 18" pool trowel.
We applied in sections no more than an arm’s reach wide. The
stabilized soil has a certain "set" as the water was pulled out
of it from the dry adobe below. This "set" affects the
workability of the mix. When first applied, it was fairly runny
and could be easily "floated" and shaped into a level surface,
but couldn’t be smoothed. As it set we did two further
trowellings, first with a 10", then a very ‘soft’ 8" pool
trowel. The second pass (10") left the surface a little grainy,
but with a tight, uniform surface. The final pass, when the
mixture was harder, made the high points slick, but left the
valleys untouched. The owner preferred this, but the slab could
have been left with the second pass.
The finely sifted soil and fine sand made it easy to work and
consolidate seams. We worked in semi-circular sections with
uneven seam lines so that the joints were irregular and random,
blending in with the floor.
The floor has been finished with three coats of Okan sealer,
which has given it a slight gloss, particularly in high spots,
which took the steel trowel in the final finish. It is too
early to tell how well this will wear. The owner sealed the
living room with linseed oil and prefers this finish. We
attempted to give a seal of Okan, then a surface of linseed
oil, but after a single sealer coat of Okan, the floor would
not absorb linseed oil without becoming splotchy.
This procedure could be replicated to produce a floor of
excellent quality and consistency. It took a single person
about twenty hours to do three passes on 7-800 SF of floor. It
took three and a half people, plus a mixer, to pour the
original 1" stabilized base. There was also several hours spent
sifting the soil for the final coat.
The topping coat was very thin but adhered well to the
stabilized base, which was wetted and softened before
application of the topping coat. Our base coat did not adhere
to concrete at all well, but since it was 1" thick, it sat on
top without problems.
Skillful Means is available to install adobe and stabilized earth flooring.
Give us a call. SKILLFUL MEANS John Swearingen PO Box 207
Junction City, California firstname.lastname@example.org
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