Making and installing a finish earthen floor

by ziggy on July 23, 2009 -- 7 comments -- Follow

finalfloor-03

In June, I finished installing the earthen floor in my cob house. In October, I built the base layer of the earthen floor, a 2.5″ thick mix of sand, clay, and straw. It dried over fall and winter (very slooowly), and once I finished plastering my walls, I moved onto completing the floor this spring. Here’s how it happened:

Preparing the finish earth floor

My recipe for the final earthen floor layer included the following:

  • 3 buckets 1/8″ sifted sand
  • 1 bucket clay
  • 1/2 bucket cow manure
  • chopped and sifted straw (to taste)

The most tedious part of making the cob floor mix was making the chopped straw. I used a weed whacker in a barrel to chop the straw (in small quantities at a time), and then I sifted the straw through either a 1/4″ or 1/8″ screen.

I decided to add the straw directly into the mix. I’ve read that others have chosen to actually sprinkle it on the floor and trowel it in, but I saw no difference.

The mix I prepared was fairly dry, but not so dry that it was that difficult to mix by foot. I would call it “stiff”. It was wet enough to trowel smooth with effort.

Laying the earthen floor

After wetting the base floor with a watering can, I dumped buckets full of the floor mix on the surface, starting in the “corner” of the house, and then working towards the door. I smacked the mix with my hands to flatten it and make it easier to trowel. I did not use screed boards, so my floor is not perfectly level. It has some light, natural undulations. 

finalfloor-02

After hitting the floor with my hands, I went over it with a trowel. I pressed fairly hard to obtain a smooth surface. 

finalfloor-00

finalfloor-01

The final floor layer is about 1.5″ thick. If I were to do it again, I would only make the final floor about a 1/2″ thick. The floor took about four weeks (with a fan blowing over the surface much of the daytime) to dry because the weather was so damp! (And I got mushrooms in my earthen floor as a result!)

Besides the mushrooms, there were a few small cracks that developed during drying. None were wider than the width of several sheets of paper, but at least a couple were over a foot long.

In another earthen floor post, I will detail how I dealt with filling in cracks (and removing mushroom scum) and sealing the floor with linseed oil.

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Eric (Knobbly) July 25, 2009 at 7:42 am

The new floor looks awesome Ziggy! I bet that feels great under bare feet. Coolish in summer and warmish in winter.

I said it before, but you are living my dream! :) Keep my dream alive- I can’t wait for the next post!

Frank July 29, 2009 at 8:14 am

Ziggy,

Very cool. You are an artist. I am so intrigued by the work and the smoothness. Plan to build a meditation hut from cob on our farm. Thanks for the inspiration.

Bryan36b July 31, 2009 at 9:53 am

Great job about how long has the entire house took also
I’m looking for a place to come and live if not perm temp really want to
Follow the dreams like the guy said above if you know of anyplace looking for
Help please let me know …. Bryan36b

Stephanie Ellison September 2, 2009 at 7:14 pm

Hello!

It looks great! I’m trying to figure out ideas for “building a house” inside my apartment. This involves leaving alone entirely the structure of the building, yet making this “inside house” completely freestanding to help provide extra insulation against the high heat and some coldness down here in Houston, TX.

I haven’t decided if I want to imitate the look of a house built mainly with megaliths or an adobe style. It has to be something in which the “walls” can be removed easily and quickly for moving and for access to the apartment walls for maintenance and wiring diagnostics, etc.

It’ll be a few years before I can move out of the city. Things have to be in place before I can do something like this.

Stephanie

Dude November 15, 2009 at 10:38 pm

Amazing work guys!!!! I will be ready to host my first owner-builder cob workshop early this next year and I cant wait to get it started.

Jahrun Chilam Balam April 17, 2010 at 12:31 am

Earth friends, wow, fantastic and inspiring. Can’t wait for the next part on crack repair, mushroom removal, finishing and curing. I am now looking forward to my own terrene floor project as in a month I will begin building a yurt pad. Any advice welcomed and appreciated. ~ namaste.

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