(And when isn’t)
When people first see earthbag, one rather ill-informed reaction is to recoil at the bags. Why not make a pure cob home instead? If you happen to live in a country without severe flooding or earthquakes, and you are fortunate to have a roof over your head while you build (ie. you're well-off financially), then build a cob house. Earthbag might not be for the European middle classes (though hey even with the sacks it's way more sustainable than the average resource squandering "eco homes"). Earthbag however is a sustainable, concrete-free life saver for people in earthquake zones, landslide zones, and the homeless who need a mud-based house in a hurry.
I love earthbag building for a number of reasons: In terms of cheap, sustainable disaster-proof structures, I think it’s hard to beat. No other building method can compete in terms of price and sheer indestructibility. Earthbag is fast to build (way faster than cob) and doesn't require much technical knowledge. Of course that doesn’t mean it’s the most appropriate method for everyone in every situation, by a long shot.
Here's my opinion on the right and wrong time to build with earthbags.
One issue with earthbag is of course the polypropylene bags. If you substitute the PP with hemp or jute, things are improving (see my post on the sacks here). But in some (or even many) cases, none of this is even necessary. Let’s start with what earthbag is good at.
When is the right time for earthbag?
1. Flood plains. Cob or adobe cannot stand flooding. Earthbag can. So if you live somewhere that could potentially be flooded, and want to build with mud, earthbag gives a lot more peace of mind.
2. Earthquake zones. It is more than a little annoying when the natural building snobs sitting comfortably on solid ground in central or western Europe sniff at earthbag. For anyone who’s lived on an earthquake fault, whether your house is going to collapse on you or not is the main thing on your mind when you build. Nothing else matters. Sorry. It is true that straw bale copes pretty well with earthquakes too (not as well as earthbag, but good enough), but that won’t help if you, like many of the world’s poorer people, live in an earthquake zone also prone to flooding, or you face landslides. Having lived in Turkey twenty years, and seen near on 100,000 people die in one earthquake, I’m in love with earthbag. While living in my house I experienced five quakes that were over 6 on the Richter scale, and have never felt so safe.
But...what about those incredible Japanese temples? Yes, buildings like Horyuji temple in Japan with its unique joinery are testimony to the ingenuity of the human spirit. But you need to be pretty well-heeled or a very competent carpentry specialist to build such a structure. It’s simply out of reach for most of the world’s population.
3. Crazy weather. If you live in a place with tornadoes or hurricanes, earthbag buildings are basically invincible.
4. War zones or trigger-happy nutcase zones. Bulletproof walls may not be the first thing on your mind if you live in some places. In that case, lucky you. In other places it matters.
In short, earthbag is a life-saving, game-changing building method for disaster areas and economically challenged communities. It’s cheap, needs very few resources, it’s low-impact, and if there are a gang of you, a structure can be built fast. It requires little technical know-how, and you don’t need to be a professional or an engineer. That’s the good news. But there are other situations when earthbag building isn’t the smartest thing to do.
When is the wrong time for earthbag?
Because of its tensile strength, a lot of people not unreasonably assume that earthbag would be a great idea for retaining walls. I’m not a fan of this, and have seen one or two collapse when water backs up behind the wall. You’d need plenty of drainage pipes running through it to solve the problem. Then there’s the issue of plastering the thing. If it’s out in the open with no covering, neither lime nor earth plaster are durable enough. So whaddya know? Concrete gets spread all over the wall, which begs the question as to what was the point of the earthbag in the first place.
Best option? Dry stone is hard to beat for retaining walls, because the gaps in the rocks act as a sieve and allow plenty of drainage. Dry stone walls are even used on a massive scale for highways here in Spain, because hey, it works.
2. Domes in wet climates
I’ve covered the whole dome issue here, but unless you are in a very dry climate a dome is often not the smartest idea. Again there are some workarounds, but creating a breathable waterproof plaster for such a building is a real challenge.
3. You’re not in a disaster zone with floods, earthquakes, or hurricanes.
If you’re lucky enough to live in a place without crazy skies or earth, then why bother with earthbag? Just build using wattle and daub, cob, or adobe instead. It could be less labour-intensive, and you don’t need the PP sacks.
4. Lone builders or couples
Earthbag is best for team builds. It lends itself to a gang of four or more. If not, it’s going to move very, very slowly, and you risk burnout. Again, wattle and daub is my method of choice for lone builders.
The arguable time for earthbag
Personally, I think there is another place for earthbag, and that is arty architecture. There is far too much emphasis on numbers and carbon footprints in the current environmental discussion, and far too little emphasis on balance, beauty, and peace. Who cares if we reduce our carbon output to zero if our world is so desperately ugly, bare, and noisy that we don’t want to exist anyway?
So I get it completely when an architect wants to create something amazing with earthbag. The technique gives rise to some very unusual and aesthetic designs. Despite the PP sacks, earthbag is still way more sustainable than many high-end so-called “eco” houses built out of concrete, or posh natural homes that squander precious natural resources (old growth trees, for example).
The upshot is, even when not used strictly in the right place and despite the PP sacks, earthbag is still an incredibly low-impact, accessible, and durable building technique.
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