CEB, Hexacube, and Hexayurt: Side by Side

We are posting a video update on the CEB flex fab workshop addition, plus news on the first Hexacube solar cubicle that we built in the short time that Nate and Ama were here on a visit. There is interesting information on our newly built stove – a hybrid wood/oil masonry stove with hot water heating and cooking surface.

The interesting point about the Hexacube is that it seems to be a solution for quickly-built, on-demand housing – if we want to house Dream Team 30 at Factor e Farm while we build a Solar Village as a team. The Hexacube is extremely simple to build – 6 identical panels are put together into a structural whole. The Hexacube is entirely modular, and even stackable – so we could stack multiple cubes in a ziggurat configuration. We compare the Hexacube to the Hexayurt in the video.

Privacy, warmth, wireless internet, and electricity. What more would one need to build the world’s first replicable, open source global village for real?

Read the video transcript below.

Here’s an update on our building adventures. We’re finishing up the Compressed Earth Brick (CEB) workshop addition – and getting ready to start building our CNC torch table there for making more CEB presses.

The last that you’ve seen was the windows being installed. Since then, we’ve built an inner utility room.

First, we drove the tractor inside to carry the 1600 lb battery bank. That went smoothly, though the tractor was almost hitting the ceiling because we did not dig out the floor yet.

Now there’s a water pressure tank in there, a shower space – to be framed up, plus the stove system. That’s a story in itself.

It’s a CEB masonry-encased wood stove. It has a Babington burner on the back side. The Babington burner has a cooking surface. There’a hot water tank inside a CEB enclosure – so it can be heated by the stove in winter or the Babington in the summer. There’s a common chimney for both the stove and Babington.

In any case, this is the only dual wood/Babinton cooking, water heating, masonry stove that we know of on this planet, if not the universe. We plan on adding further heat exchangers so that we could run a steam engine for electricity generation when we using the stove for winter heating.

So that’s as close to a true masonry stove as we got.

We also did some plastering inside, put in a glass door.

But we need to build ourselves some more housing for our budding village. We’re looking at expanding the population to 30 by year’s end. So the most economical year round solution turns out to be the Hexacube.

It’s modular, industrial, quick, and simple. It’s 6 standard framed panels – 8×8 feet in size – with 2×4 lumber and Oriented Strand Board (OSB) faces. It’s got R13 insulation inside, and it takes about a day to build with a team of 4. Even 2 strong people can move a panel by hand. The panels are light enough so that 4 people can move them into place – even the roof. For the roof, we did take off the OSB on one side to reduce the weight a little, as we had to lift that last panel over our heads.

We screwed the panels together with 2x4s and 3” drywall screws on each of the 12 edges. The whole structure can be taken apart into panels readily, and moved or modified. We can make several cubicles, and even stack them into a ziggurat configuration. These panels are structural, so this is a move above temporary housing – into housing that lasts on the order of decades.

The solar cubicle rests on cinder blocks, and it’s insulated on all sides. The total cost is $380 without the stove. We used driveway sealer for paint – we found out that it’s the only type of coating that can be applied quite easily in near-freezing and even freezing temperatures – as opposed to paint or tar. The driveway sealer remains quite fluid in cold temperatures.

We put in a little army stove, lined it with CEBs, and lined the wall with aluminum flashing.

The Hexacube solar cubicle proved that we can build on-demand accommodations – in about a day, at about $6 per square foot. This is just standard construction – which is fast to build – unlike natural building.

We expect the solar cubicles to be the transitional housing as we build our Solar Village from Compressed Earth Bricks and local lumber.

Here’s a comparison of the Solar Cubicle to the Hexayurt. We call the solar Cubicle a hexacube in reference and deference to Vinay of the Hexayurt.

Well, for our purposes – the Hexayurt does not do a good job in winter. Nick was cold in there, with a stove – when it was 20F below 0. The Hexayurt as we built it from OSB – has no floor, no insulation, and is more or less a temporary structure.

All in all, the advantages of the Hexacube are: basically a permanent, modular, stackable structure, twice as fast to build as the OSB Hexayurt, with minimal site preparation. The The disadvantages are that it has about half the usable floor area for a similar cost. It is not easy to insulate a Hexayurt because of its corners. If you use the cheapest insulation, fiberglass – you’d essentially have to frame up the entire Hexayurt, which becomes too expensive in time and materials. On top of this, the Hexayurt has no floor. So we’d recommend the Hexayurt for wind-sheltered, dry, warm areas. In windy areas, the Hexayurt would have to be tied down, which we did here with some stakes at the base.

So the Hexayurt lives as a good summer structure.

Tune in next time for further adventures, at Factor e Farm.


  1. Ama

    ..where anything can happen!
    (at Factor e Farm!)
    The cube was warm even without the stove, simply from Nate’s body heat whilst he was laying bricks and putting up flashing to prevent the walls catching fire from the stove..its so nice to stand in a fully insulated cube! We slept fitfully in the HexaYurt untill Nate fuigured out where and how to lay a fire with the front door on the stove cracked open, and bottom vent fully open, fire to the front – then all was well and we warmed the Yurt up nicely.

    We’ll be back to help build more. What about a 8x16foot larger Solar Retreat? what fun! OneLove, Ama

  2. Vinay Gupta

    Might be worth noting that if you want to insulate a hexayurt, there’s two ways of doing this.

    The first is that you use something like Reflectix – foil-lined bubble wrap – as the inside insulating layer of the Hexayurt. It’s about $300 to get R9 for 166 square feet, and there’s an under-floor grade which you’d put below a layer of plywood to get an insulated floor.

    That comes out to about $3 per square foot, or about half the cost of the cube.

    The other approach is to use SIPs just like the ones you made for the Solar Cube, plus “shims” – pieces of wood cut to 15 or 30 degrees as appropriate – to join the panels into the Hexayurt shape. It’s the same construction technique, just with a more efficient shape and a little math.

    You actually get a significantly higher effective R-value from the Hexayurt because of the improved surface-to-volume ratio of the structure. The cube has 0.625 square feet of wall per cubic foot of enclosed volume. The hexayurt has 0.36 square feet of wall per cubic foot of enclosed volume. For a given quality of insulation, it will have roughly half the thermal loss to the exterior as the cube will.

    Likewise, framing a floor for the Hexayurt is not a big deal: seven posts, a 4×8 frame, and insulation of either the fiberglass or the reflectix variety.

    Anyway, you guys should have told me your Hexayurt was cold and I would have advised on insulating it. The geometry is really much, much more efficient than the cube and it’s fairly easy to insulate if you want to build it in cold weather areas. It’s not the *shape* that is cold, it’s the construction technique!

  3. Ama

    Hmmm. I would agree with Vinay, and add that its not the Stove that didnt work, it was how well or poorly the Fire is laid! =)
    but all is well.
    heck, maybe our bext visit we should break down the HexaYurt, build a floor platfrom, insulate the panels by doubling them w Fiberglass (or said Reflectix… how much is it in MO, do they sell it locally? Is it locally replicable…?

    heck, can we make R-value up with treated Sheeps wool battings or Clay-slip-dipped Straw filling jam inside doubled walls…? Thats CHEAP and LOCAL INSULATION for ya)

    Cheap or free and LOCAL is what i think the world needs.. what say ye, men?

    Love from MI,

  4. Jeremy

    Sound’s like you’ve got the right idea Ama! ;]

  5. Mathew

    Oh man! Molly and I are so excited to try it out! we used to live in an apartment that size, only without a view.

  6. Richard Schulte

    when i helped build the hexayurt, i always assumed it would make a nice summer home! its white, got tree cover, and, without insulation, quite breezy. There is some sun exposure on the north side which will add a little heat before sundown. Itll be great during the groggy, sweltering missouri summers, especially as Factor E is in the upland grand river basin, thus part of a very active and humid watershed. id say keep it the way it is and use it as a shed during the winter. if it were insulated it would be so warm itd be nearly useless during the summer. hexayurts are multipurpose creatures.

  7. Marcin

    From Lucas:

    There must be a way to cut “shims” using most if not all available wood. Or they can be just long wooden “cylinders”, with mud to fill the gaps between the cylinders and the flat pieces.

    Actually, what might be fun would be a weekend competition. Leave both your name and the yurt behind, of course. The competition might be multi-site, but you have to provide video, or at least sequential pictures.

    Add some fundraising a la, and it’s done. Global Shelter Swadeshi Weekend is born.

    Check out very interesting fundraising idea by AKVO –

    Twestival reference:

  8. Kiashu

    Wow, your brickwork is a bit rough, I hope it lasts 🙂

  9. Lance Culp

    Although I find the Hexayurt to be a very interesting idea, I have to wonder about its practicality for those in the northeast and mid west, especially during the winter. Certainly, some sort of heating method is needed.

    If building a fire is an option, possibly heating stones and then placing them in the structure would be a way to go. I’m thinking of the sort of techniques used for various sweat lodges. Staying warm and dry is a must.

  10. […] If you need a four season structure, follow Vinay’s guidelines in the Hexacube comments and insulate a Hexayurt, the Hexacube is not a mature design. Categories: Factor e Farm, Global […]

  11. Tony

    You guys are well down the right road, thanks for sharing your insights.I’m inspired

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