Earthbag Cellar – Guests, Roof, Floor & Burial

Iulia asked for a few pictures of the cob process … so: first we make a dry mix (we call a lasagna) of sand and our (clay rich) soil in a wheelbarrow … dump it on to a tarp and add water while dancing it into a consistent mix:

We then add straw and dance that in … then roll the mix into a sausage by pulling the tarp (we repeat all this twice … so that the straw is mixed in well and not clumped):

… and that results in cob (which can take on various textures depending on the specific recipe and what we want to do with it):

… and for us it has been many batches going on to the roof … we previously completed the roof on top of the small room (relatively thick cob layer to fill and seal round acacia logs) … and then moved on to the large room (relatively thin and uniform cob layer to cover and seal flat boards):

… and if I recall correctly after 10 batches of cob the large room was also covered:

… we then had an unexpected visit from Alin who stayed with us for a couple of days … his help meant that we finished the entrance segment of the roof earlier then expected (forgot to take pictures of that … but basically more cob).

… and we decided to take advantage of Alin’s presence to tackle the floor. The floor was originally planned for later in the project (after the walls  were done!) … but since we had Alin’s help, and since the floor takes a few weeks to set, and since we are going away for a couple of weeks … we decided to do the floor …. another first experiment for us … another cob recipe … and another application technique … and I am blown away by the versatility of this natural material:

We were then in for another surprise. Alin’s friend Sandu (a high energy athletic person!) decided to also stop by for a short visit on his way home. He arrived late (~21:30) just as we were winding down. He jumped out of the car, changed into work clothes and started cob-dancing … “one more batch” he said … again … (Iulia hung some lights) and again … and again …. and again …

….and we worked almost until midnight … got a large part of the floor done!

… then the next day Sandu called Alin again in the morning … he wanted to see the place in day light and help some more … and he came out with his wife and Alin’s wife:

… and we finished the floor!

The next day (monday) we were planned to have the excavator over to do the burial, but he was only able to get here on Teusday (yesterday). While Iulia was doing our weekly market shopping I completed the plastic covering (if you are wondering about water draining and a flat roof … there is more to come!).

… but then the weather got cloudy with potential for rain … and so I placed tarps back on the plastic to protect it

… fortunately the weather cleared and we were on for burying the cellar.

and the first corner started going under.

… and then the back was almost filled

… and I stopped taking picture because we needed to get involved in moving and directing soil (careful to avoid overloading the roof).

The front sides were a bit difficult because they ended up being very steep (it was a tight construction area). When we excavated into the hill I felt that we dug in too deep … it turns out deeper would have been even better.

the last part was the inner front corner … and that proved the trickiest place to fill (limited access for the excavator).

… and after ~3 hours the cellar was buried … and, as planned, only the opening into the hill remained.

we are going away for two weeks … while we are away everything will have a chance to settle: the newly placed earth, the structure itself and the earth floor. When we come back we will create the water-shed umbrella and do the final burial … then electricity, plenty of finishing work, doors, shelves … healing the surrounding earth … still quite a journey ahead!

We are both tired from the last intense weeks … so glad to be pausing the work and taking some time to relax and breathe.

3 Replies to “Earthbag Cellar – Guests, Roof, Floor & Burial”

  1. Great to follow your progress!
    Pahs does not mention using cob but I guess using it gives a sturdier and even surface – still I am thinking that cobbing only the gaps beyween the logs and then adding a soil layer might have been enough – much less labor intensive… Why did you decide to put a layer of cob all over? Any particular reason?

    It seems to me that the finished cob above the structure was not dried when you covered it with PVC and then earth… This means that the cob will dry only from below among the logs into the cellar – is that right?
    I don’t have many experiences but did notice that sometimes fungae are very fast settlers to the wood logs (especially when damp+warm)… Even though acacia (robinia??) holds well in the earth the outer layer of a wood ( sapwood?) is not that durable…

    I wish you a great summer days, great finished cellar and a steady gain of knowledge along works yet to be done!


    1. Thank you for your continued presence Klemen 🙂

      The cob on the roof has obvious functions:
      1. To seal the roof – both the logs and boards had gaps that needed sealing.
      2. To flatten the roof and offer a flat layer that can wrapped with plastic.
      3. To protect the plastic from being torn by rough surfaces from the wood underneath.
      4. To complete what is basically a monolithic shell that caps the whole structure (though the layer on the boards is only ~2cm thick)

      But there is another subtle function which is where the cob / clay comes in: if any water does penetrate all the other layers of protection and reaches the cob it will not only be able to absorb it and dry out gracefully … but it may even expand and seal itself.

      You are right the cob was not yet set … but it has plenty of space to breathe underneath and I hope that together with the passive ventillation system it will gradually dry out. Also, all the wood (acacia and boards) was protecting through charring.

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