From Hemp to Earthships

I believe and have passionately shared my belief that hemp-lime construction is one of the best methods of construction available today (at least in the Romanian climate in which we live). We were planning to build with hemp-lime and our architect designed a magnificent house for us – unfortunately we could not afford to build the house so the project stopped and we are living in the slightly renovated traditional Romanian house on our property.

Hemp Difficulties

Building with Hemp was going to be an uphill effort. It was difficult to source materials (we finally found some hemp in neighboring Hungary) and natural hydraulic lime (NHL) is also a rarity here (we found it imported from Italy and Germany). It also seems we would have had quite a challenge mixing the hemp-lime mortar since the best suited tool (pan mixers) are not to be found here. We also had a relatively short window-of-opportunity to build since hemp-lime needs to set (~8 weeks) before the first frost appears – and it arrives early here. So despite our passion and investment in hemp we can say in retrospect that there were many cues pointing us away from it.


When we realized that there wasn’t enough money to build the designed house we started looking at ways to scale down and simplify the house so that we could build it. One of the things we explored were the foundations. Though we had relatively cheap foundations they were still a major expense in the project.

Our house is to be built on a gentle south-facing slope and the plan was to excavate so that the back of the house the excavation was about 1 meter deep. Then we would fill the entire surface with rocks – starting with large rocks (~40cm) and then adding layers of smaller and smaller rocks until we arrive at gravel and sand. On top of that there would be a concrete slab which we preferred to avoid but was required due to the green-roof planned for the house.

With these foundations planned and in mind I first came (about a month or two ago) across two new (to me) themes: rammed-tire construction & underground houses.

Rammed tires is a method of construction where used car-tires (abundantly available is modern garbage) are packed full of dirt and stacked to create a thick monolithic wall that is its own foundations. These need to be built on undisturbed soil and no additional foundations are required. Inside they are finished with earth.

Underground houses (though they may conjure up uninviting images of war shelters) is an approach to building houses that are to some degree (many options here) surrounded by earth. Though there are numerous advantages to this the one that stands out in my mind (as we are living in a small and inefficient house that consumes loads of firewood and the work involved in it) is energy efficiency. Regardless of how you deal with the house fabric (insulation, thermal mass, etc.) when you build a house above ground and its freezing outside then you need to deal with subzero-temperatures surrounding the fabric of the house. When you build a house underground and its freezing outside then you are dealing with a relatively warmer (~10 degrees Celsius) and steady (a couple of days ago I witnessed an almost 20 degree Celsius shift in 4 or 5 hours!) surrounding. In the summer when its hot outside the earth is relatively cool so that works for you too.

So, with that in mind, I’d like to qualify my initial statement in that hemp-lime construction is one of the best methods of construction available today IF YOU ARE BUILDING ABOVE GROUND.


You can’t get far reading about rammed tires without coming across Eartships. An Earthship is a concept developed (if I am not mistaken – way back in the 70’s) by Michael Reynolds – an American architect. His vision is to create an autonomous house generating its own electricity (solar/wind) and water (rain run-off collected from the roof) all built with waste materials that mankind has generated in abundance (tires, beer-cans, wine bottles, etc.).




Ironically my first (and still leading) impression is that it is an impressive vision (amazingly elaborate and thorough) but also one that is anchored in the indulgent and abundant USA mentality (a recurring symptom in most of the “green” construction methods I have come across). Though Earthships are designed to be owner built they are still very expensive and a far cry from becoming something anyone on the planet can afford to live in.

We could not afford to build an Earthship based on the template described by Michal Reynolds and we are very well off compared to the general population of Romanian villages. So bringing Earthships into our context is quite a challenge.

Gradual Self Build

There are numerous benefits to Earthship construction compared to hemp-lime construction and though I will mention some of them there is one that outshines all of the others.

Earthships are designed to be owner built and indeed my searching and reading online seems to indicate that Earthship is one of the most popular self-build techniques for non-professional builders.

But in addition to being suitable for owner-built houses, Earthships can be built gradually. With relatively low costs we can start next year to pound tires that will make up the shell of our house. It may 2 or 3 years (unless we get help) but we can start and as we do that we can continue to develop our income stream and as funds become available invest more and more in the construction. Given that we have a temporary house to live in there is no need to wait, no rush and no pressure at all.

Earthship – Hemp Comparison

Beyond self build there are numerous points of comparison I’d like to make a note of in comparing hemp-lime build to an Earthship-like build. It should be said that what follows are things that matter to us including choices we may make that are not directly true to the core Earthship concept.

Feature Hemp Earthship
Foundations Like all natural fiber based walls hemp needs to be lifted above ground level so that it does not come in contact with water that may drain past the building. In our case the green roof required a foundation that could carry and distribute the load of a roof structure, earth, plants and snow. No foundation is required. The walls themselves are a foundational structure. The tires, when rammed with earth way over 120kg each (they have to be packed in place because they cannot be moved). In addition the tire walls are either completely immersed or bermed with earth which adds additional support (and load on the walls!).
Floors Both building systems can incorporate a variety of floor systems. In both cases, in our climate, there needs to be good thermal insulation (our floors can get to be very cold) and good vapor barriers
Walls Hemp-lime is a non-structural material which means that it is not load bearing. Therefore hemp-lime walls are an infill for wood framing (usually either stick framing or post and beam). There is also need for shuttering (during construction) into which the hemp-lime mortar is cast. Used tires pile up as garbage almost everywhere in the world – so besides the effort of finding it, sorting through it and transporting the tires to your build site there are no additional costs. It’s as simple as laying them on the ground and then the (very) laborious of pounding them with dirt. As we are not in a rush … we don’t mind taking the time to pound tires.
Finishing Hemp-lime walls are porous and therefore breathable walls so they require a breathable finishing (usually lime-based). On the outside, regardless of finishing, the walls need to be protected with generous eaves. On the inside tire walls are finished using natural earth finishes they I am assuming that lime can be used as well. This finishing is actually more critical in tire walls because the wall itself is not porous or breathable – so the finishing layer needs to be (for humidity responsiveness). The finishing is a pretty thick layers because first the gaps between the tires need to be filled to achieve a smooth surface – and only then can actual finishing layers be added. As for the outside there is no finishing issue since the walls are either buried or bermed (there is however an insulation issue – see below)
Doors Our hemp house had quite a few doors designed into it. In that sense it was a typical house. The original Earthships were, except of course for the entry to the house, without internal doors. They have evolved to the point where more elaborate internal design can lead to doors – so I’d say it’s pretty much the same as a regular house (although there is the option to build with much less doors.)
Windows Windows in an above ground house are a pain. They are expensive (if you want good windows). They need to be installed with careful flashing to avoid leaks of water into the house. They need to be constructed and installed with precision so that they are also air-tight. In a do-it-yourself build they can be quite troublesome. Earthships have no side windows – all the glass is in the front wall which is all glass – it is a relatively expensive element that requires basic wood framing, double-pane glass and very good flashing. The more modern Earthships actually have two glass walls – one is the outer wall which delineates the greenhouse and corridor to rooms; the other is the internal wall which encloses the rooms which is also mostly glass because we want as much sunlight to penetrate into the rooms. I have a feeling that the Earthship is somewhat simpler in this sense then a regular house – though I think the costs maybe similar if not higher.
Earthships also incorporate skylights primarily as a ventilation but also as a light source. This is something that can be self-built so the expense can potentially be somewhat reduced compared to ready made skylights.
Insulation Hemp walls need no insulation – they behave wonderfully both in terms of thermal mass and insulation. They do, as mentioned above, need to protected from moisture on the outside – wet walls are not good insulators. Originally Earthships were built without insulation under the working assumption that they should interact with the earth itself. The modern evolution of Earthships in cold climates (where the earth, though warmer then the air, is still colder then a comfortable living temperature and could therefore suck heat out of the house) include insulation – usually rigid foam insulation (not very ecological) that is installed at a distance of about 1 meter from the wall itself (the space between the insulation is filled with earth).
Roof Hemp homes can be built with almost any roof system. We were planning to build a green roof. Insulation is required and again can take on many forms. Standard Earthship roofs are designed with a primary function (besides shelter of course) of rainwater harvesting. Here too insulation is a must and can take on numerous forms though standard Earthships use rigid foam insulation. We are currently leaning toward a green roof. This will deserve a dedicated post so stay tuned 🙂
Space Heating Hemp homes can be very energy efficient if they are built properly which includes: airtightness, ventilation, passive solar, etc. But my intuition tells me that they still require heating which is can be a very challenging and complicated and expensive issue. Still they are above ground houses and need to cope with the dynamics outside environment (though the hemp walls, being constantly dry, tend to this very well compared to other wall systems). Earthship heating requirements are probably much lower even then that of Hemp:

  • Air-tightness is almost a natural consequence of burying your house in the ground … only the front wall deals with air leaks. Though these air leaks are not very critical because (a) the front face is a greenhouse which gets very warm (when the sun is out); (b) needs ventilation; and (c) is separated from the living area by another wall system.
  • The house itself is embedded in a drastically warmer temperature – that of the earth (at coldest freezing), then houses above ground level (at coldest subzero temperatures).
  • The entire south face of the house is a glass wall which utilizes passive solar to the maximum
  • A basic Earthship is designed so that the house is not deeper then one room – so most of the space directly benefits from solar energy.
  • The earth has inherently vast thermal mass because of its (a) thick earth rammed walls; (b) an additional 1 meter thick earth mass; (c) a layer of insulation; (d) the rest of the earth acting as a relatively stable thermal mass.
  • The internal walls, earth wall finishes and potentially earthen floor also add valuable thermal mass which can store heat and gradually release it back into the space.


We are continuing to study and investigate Earthships and how they can apply to us. It feels promising.

We have been blessed with a temporary house in which we can live yet it is not a house which can become a house that supports and embraces us. This house is a wonderful shelter which can make building our new house a pleasant and healthy process.

The thought that we can begin a building process next year from mostly salvaged materials and then gradually move on with construction as work progresses and more money becomes available … and maybe move into a wonderful and pleasant house in 3 or 4 years is … joyful!

We Won’t Be Building with Romanian Hemp, but …

After weeks of observing a sample of the hemp-shivs we found piled up in Carei we decided to use it for construction. But, for reasons too boring to go into here, we had to move the hemp from the huge outside pile into a temporary storage (we could not yet ship it to our house because heavy trucks cannot get there yet and insufficient storage space). Yesterday we headed out to Carie together with Sabin to move our hemp. With the help of our local supporters we managed to find a construction company that agreed to both transport and store the hemp for us.

We started the day (after a 3 hour drive to Carei) by visiting the storage place – which was ample but needed to be cleared out and cleaned a bit. It was south facing which was great as air and sn would have continued to dry the hemp (not to ourselves: Andreea had a bad feeling from whn we arrved at the storage facility).

We thendrove back to the hemp-pile where we met again with Rodica Maxi. It took some time for things to get moving (a tractor for loading and a 30 cubic meter truck for moving transporting the hemp). By this time we were preparing ourselves for an extended visit including one night. It was etsimated that each truck load (including loading, driving and offloading) would last 40-60 minutes. We were planning to move ~14 trucks (for 2 houses) which meant that the job wasn’t going to be completed in a single day.

Finally (at around 12:00) we got a call that the truck was arriving so we headedot to greet and direct it. Here are (left to right) Andreea, Rodica and Sabin waiting for the truck (note o ourselves: a dog got hit and badly injured by apassing truck right before our eyes – we saw it coming and couldn’t do anything about it).

The truck arrived and we headed to work. The top layers of the hemp pile were clearly rotten (not good for construction) and they needed to be pulled off. But as the tractor came in and started moving it around we realized that the rot went deeper.

Though there was plenty of usable material it was mixed in with many rotted pockets and there was no clear or consistent pattern that we could work around. Also, it seemed that the tractor’s gross action was actually messing up what good pockets of material that were still there. So we attempted some manual intervention.

But it just wasn’t meant to be. We looked around, touched the material, dug some holes and there was no feasible way to separate out the good material. The only solution we could come up with involved lots of careful ad caring manual labor (10 people over a week) to create a potentially usable pile of material. That, together with other considerations such as the weather (expected rains) and logistics (loading, moving and storing) piled up to an unattractive solution. So, content with our effort to build with Romaian hemp we decided to abort. Here is Sabin taking one more trip around the pile before we walked away.

This hemp can be a wonderful fertilizer but not much more. In fact Rodica took with her a sack of what looked like beautiful half-composted humus to use in her flower garden (I envied her, I would have loved to have this pile as compost for our land!).

We were only slightly disappointed – as we knew from the start it was a shaky upill effort. We were really hoping to salvage the last available hemp in Romania for the first hemp-lime construction but it didn’t work out.

It was agreat opportunity for us to spend some more time with Rodica who refused to give up, harnessed our passion and energy, made a few calls and an hour later (as were having a late lunch together in a restaurant in town) she informed us that she has probably found an alternative source in Hungary (close to the Romanian border). It is going to be more expensive per ton (minus all the transportation and storage overhead we were ready to endure) but much cheaper then most of the industrial hemp we found in Europe. It is a better quality material, clean and probably packaged. Rodica said she wll be visiting the manufactrer in the coming weeks, she will see the material and send us a sample and also offered assistance in arranging shipping (when we need it, where we need it) through her company. How wonderful 🙂 and the journey continues 🙂

Have we found Hemp Shivs for Construction in Romania?

On Feb 23rd Andreea and I went to see some hemp. Two people sent us to Carei in the northern area of Satu-Mare where once (until ~3 years ago) there operated the last decortication (the process in which hemp fibers are separated from the wooden core which we need for construction) in Romania. It was a 5 hour train ride in each direction – and on the way there I was amused as I realized how far my life had come – I was excited to be on a 10 hour journey to see … hay!

This was also a wonderful opportunity for us to meet with Dorin Pop, a construction engineer who works with Teodor Pop of Lux Perennial. Dorin met us at the train station together with his friend and together we drove off to see hemp.

The picture below is what greeted us – deserted tanks where water used for retting (partial decompisition of the glue-like materials that holds together the fibers and the wooden core). In the background are fields where hemp was once grown. At the turn of the century in the area of Satu-Mare alone there used to be 8,000 hectares of hemp (for fiber) crop.

We met with Rodica Maxi who was the founder and owner of the decortication plant. The plant has been shut down for over 2 years, now there are just a couple of offices which are also in their last days. Rodica is one of the people responsible for recent legislation that lays out a simple legal process for acquiring license from the government to grow industrial hemp. She is looking forward to rebuilding the hemp-industry in Romania. Here is Rodica proudly showing and explaining to us abou hemp.

This image of a picture Rodica shows us standing proudly by fields of hemp seems to hold an entire history of hemp in Romania.

After a pleasant conversation we went to see the hemp. We were disappointed to find that the hemp is kept outside. A large venting pipe used to run from the plant and into this field where the leftovers from the decortication were dumped. We were surprised to learn that a form of hemp-construction has been going on in Romania for quite a while – that churches often purchased the hemp-shivs and used them as a stucco-sublayer for renovation and decorative paintings.

According to Rodica it is a pile of approximately 200 tons of hemp with about 10% fibers. This next image with people in it can give you some idea of the dimension of the pile.

We were extremely excited to be standing next to this pile of hay. This is the first time we’ve seen hemp and in such large quantities! The top layers are wet and rotted and therefor useless to us for construction though they would probably make an excellent fertilizer. But the middle layers looked very promising and we took a sample with us.

On the way home I kept playing around like a child with the material we took with us. As hours passed on the way back we realized that there may be a problem with the material. Outside is was probably frozen and therefore  looked and felt dry. But after spending some time in a sealed plastic bag it warmed up and began to sweat and a moldy smell began to form. We’ve been monitoring it for a few weeks and though visible mold has not appeared the smell is still there.

Rodica has offered us to take as much as we need at a symbolic price. It would be our responsibility to package and ship it to our land. It is a magical opportunity but we are still not sure about the reliability of the material for construction. We don’t want to build a house only to find after a couple of years that the insulation and breathability of the walls has been compromised and that they are rotting.

Stay tuned for more 🙂

Chronological Images from Nauhaus

It seems that Clark & Tim, the guys who wrote Building Green, moved in the Passivhaus direction. They have a project called Nauhaus where they are attempting to bring together their past experiences with the Passivhaus standards.

I believe, as I have written before,  that the Passivhaus standard is not a practical nor sustainable form of construction – though there are some excellent and applicable ideas and inspiration to be drawn from it. The Nauhaus was built with hemp, which from the theoretical (at this point) knowledge I have gathered simplifies, ecologizes and reduces costs of many construction aspects. Yet because of Passivhaus standards Nauhaus also reintroduces many complications which I find … uninspiring. Just this morning I was reading their chapter on building a green roof, then I came across the massive, industrial insulated crane-lifted panels they used in the Nauhaus project. Though I can appreciate their efforts to move forward and improve … it feels to me like they took a wrong turn somewhere … I think Passivhaus had something to do with it.

I was surprised to see in some of the images the Tradical procucts and then to learn that the interview I posted with Ian Pritchett was actually from the Nauhaus project.

Amongst the information on their website is an educational set of posts with images showing the contruction chronology – from foundations to a completed building. At this point in my education, these documented processes are extremely useful and rewarding. The chronology starts at the end of this page – from where you can scroll up and forward in time to see the project progress.

My main take from these images is on some thoughtful tricks on how to efficiently prepare and install formwork for the hempcrete as you can see here and here:

And also this super-simple ingenious carpentry lesson from Tim – as he creates a simple tool for measuring and placement of formwork from here.

Self Grown Hemp for Construction

Wouldn’t it be ideal if you could grown your own hemp and then use it to build your home? 1 or 2 hectares of hemp stalk is potentially all you need to harvest enough building materials to build a house. Imagine that – growing your own house!  … but it isn’t a simple thing to do.

The hemp plant has four elements: seeds, leaves, fibers and a wooden core. The part you need for construction is the wooden core – also called the hurd or shiv. Separating it from the other elements of the plant requires effort. You need to grow the hemp, deffoliate it (remove the leaves) before harvesting, harvest or remove the seeds, harvest the stalk, let it ret (start decomposing so that the fibers can be separated from the hurd) and then decorticate it.

This finally step of decortication seems like the greatest obstacle – this is the process of separating the fiber and the wooden core. It can be done either through massive manual labor (of which I don’t yet have all the details – but it involves collecting the harvested stalks into small bales and then beating them to separate the fibers and wooden core) or in an industrial process. The indutrial process is usually designed to extract the fibers, the actual wooden shiv is simply a left over of that process.

It would be so much easier to grow your own construction hemp if decortication could be avoided – and this may be possible but my understanding is that it depends on the climate you live in. This research paper on Hemp-Concretes claims that it is possible to create hempcrete using both shives and fibers – BUT it is important to note that the research focuses on the structural aspects of the resulting hempcrete. It does not address the effect of fibers on insulation and breathability of the hempcrete.

Introduction of fiber to the hempcrete mix can cause humidity problems. When fibers are clumped together they tend to draw moisture and that is not something you want to happen in your wall. According to Steve Allin it is possible to add 5%-15% of fiber to the mix but not much more. This may be less of an issue in a hot and dry climate – but otherwise the risk seems unwarranted.

Maybe when the hemp industry matures it will be possible to cultivate stalks with very little fiber and a massive wooden core – which could then be used in whole? For now though it seems that self-grown hemp is not a feasibly reliable option for construction unless you have the means to decorticate it.

Building with Hemp

There is only one book (worthy of being called a book) I know of (in English) – Building with Hemp by Steve Allin. It isn’t the one and only book you will need to actually build with hemp – but it provides the best overview, explanations and images I’ve encountered so far on doing so. It touches on many hemp-effected aspects of construction. You will still have to do a lot more inquiring and apply your own common-sense but this book will be an excellent road-map for you on your journey.