Note: If you’re new to earthbag building, please read the introductory Step-by-Step Earthbag Building Instructable first. Also, my new Earthbag Building Guide and Earthbag Building DVD are now available. Stay up-to-date on all the latest earthbag news by following our Natural Building Blog.
We built this earthbag roundhouse in 2010 as part of an earthbag workshop in Thailand, and finished it later that summer. Roundhouses are perhaps the simplest, fastest, easiest earthbag structure to build. We’re extremely pleased with the results, especially in terms of strength and cost. This is one of the strongest structures I’ve ever worked on in my 30-plus year construction career. The main impression is one of incredible fortresslike strength - massive walls with no sway. I’m sure it could easily withstand a direct hit by a speeding vehicle. This is no exaggeration. There’s been at least one incident where a drunk driver hit an earthbag wall and only chipped the plaster. (The vehicle was totaled.) Earthbags also excel at withstanding floods, hurricanes, tornadoes and earthquakes. Engineered plans are now available for whatever conditions you face. Earthbags are even bullet resistant, as explained in our highly popular blog post where compressed earth withstood 50 cal “BMG” 661 grain Full Metal Jacket rounds. Bullet Resistance of Compressed Earth
The other key advantage of earthbag is cost. For our roundhouse, we wanted things to look nice, of course, but we didn't want to spend a fortune. The final cost came out to $11.50/square foot. Most stick-built houses are $100/sq. ft. and up, so this roundhouse demonstrates how anyone can build their own home even on a very tight budget. We used a few basic, low cost methods to class up the roundhouse: rounded window and door openings (free), nice colors (no extra cost), curved bathroom wall and buttress (no extra cost to create curves), exposed wood and thatch roof (dirt cheap), earthen plaster on the interior (really dirt cheap), and lots of beautiful old windows for views, ventilation and to add a sense of spaciousness. In summary, build small -- just what you need, use simple shapes, pay with cash, and add on later if needed.
Basic project information:
18’ exterior diameter; 15’ interior diameter; 177 sq. ft. interior floor space; total cost of materials: $2,045, which is about $11.50/square foot
The following instructions assume you have cleared and leveled the site, removed topsoil, positioned fill soil around the building site to minimize work, dug a trench to stable subsoil, buried any utilities, put about 12” of gravel in the trench, and added a center pole with stringline to measure the radius. Bags or tubes can be used. We demonstrate bags, because they’re often available recycled for very low cost. My YouTube Channel has short video clips that show each step of construction.
We built this earthbag roundhouse in 2010 as part of an earthbag workshop in Thailand, and finished it later that summer. Roundhouses are perhaps the simplest, fastest, easiest earthbag structure to build. We’re extremely pleased with the results, especially in terms of strength and cost. This is one of the strongest structures I’ve ever worked on in my 30-plus year construction career. The main impression is one of incredible fortresslike strength - massive walls with no sway. I’m sure it could easily withstand a direct hit by a speeding vehicle. This is no exaggeration. There’s been at least one incident where a drunk driver hit an earthbag wall and only chipped the plaster. (The vehicle was totaled.) Earthbags also excel at withstanding floods, hurricanes, tornadoes and earthquakes. Engineered plans are now available for whatever conditions you face. Earthbags are even bullet resistant, as explained in our highly popular blog post where compressed earth withstood 50 cal “BMG” 661 grain Full Metal Jacket rounds. Bullet Resistance of Compressed Earth
The other key advantage of earthbag is cost. For our roundhouse, we wanted things to look nice, of course, but we didn't want to spend a fortune. The final cost came out to $11.50/square foot. Most stick-built houses are $100/sq. ft. and up, so this roundhouse demonstrates how anyone can build their own home even on a very tight budget. We used a few basic, low cost methods to class up the roundhouse: rounded window and door openings (free), nice colors (no extra cost), curved bathroom wall and buttress (no extra cost to create curves), exposed wood and thatch roof (dirt cheap), earthen plaster on the interior (really dirt cheap), and lots of beautiful old windows for views, ventilation and to add a sense of spaciousness. In summary, build small -- just what you need, use simple shapes, pay with cash, and add on later if needed.
Basic project information:
18’ exterior diameter; 15’ interior diameter; 177 sq. ft. interior floor space; total cost of materials: $2,045, which is about $11.50/square foot
The following instructions assume you have cleared and leveled the site, removed topsoil, positioned fill soil around the building site to minimize work, dug a trench to stable subsoil, buried any utilities, put about 12” of gravel in the trench, and added a center pole with stringline to measure the radius. Bags or tubes can be used. We demonstrate bags, because they’re often available recycled for very low cost. My YouTube Channel has short video clips that show each step of construction.
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Signing UpStep 1: Earthbag Foundation
Earthbag foundations – gravel-filled bags or stabilized bags – offer many advantages over reinforced concrete foundations and work well with many types of sustainable buildings. In particular, they are low-cost, fast and easy to build, require no cement (a major expense and cause of global climate change), and require no forms or expensive equipment. In cold climates you can use lava rock or pumice to create an insulated foundation. This one simple step can save you thousands of dollars over building with concrete, and cut your energy costs.
Typical earthbag foundations are made with poly bags (double-bagged for strength) filled with gravel. Aggregates are preferred for foundations because they will readily drain away any moisture and prevent wicking into the wall system. Some prefer to use stabilized soil in earthbag foundations, seeing it as a longer lasting solution. The jury is still out, but it appears poly bags kept out of sunlight can last hundreds of years, so gravel-filled bags should last at least a lifetime.
Simply fill the bags in place with gravel. Stitch the ends closed or fold the bag end over. Butt each bag tight against the previous bag. Tamp the bags flat after each course is complete. Add two strands of 4-point barbed wire between each course. Add courses of gravel-filled bags until you’re at least 6” above the risk of moisture damage.
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I find your ideas very inspiring
I intend to build a big roundhouse about 33 feet diameter in Udon Thani Thailand. It seems to me that the roof will present a problem in that I can’t think of any cheap material to build it with. I don’t want thatch because of the insects and the short life span of such a material. I actually want to include a central pole/tree trunk as an interior feature rather than using a compression ring.
I can get bamboo for next to nothing and cover the roof with it which should look good from the inside but I’m at a loss then to know how to waterproof it on the outside. I don’t want to have to screw tiles to the bamboo if I can help it.
I also want to build the site up with soil to about half a metre AFTER I build the house. So I think I need a solid foundation. If I make the foundation slightly higher than half a metre and us earth two bags side by side where do I place the single earth bags for the walls…….in the middle of the two?
Roof: You can use bamboo, wood or metal framing. Bamboo is rather difficult to work with and requires treatment to prevent rot. It's not commonly used in Thailand and you'll have a difficult time finding what you need. Metal framing is actually a good choice in Thailand because it lasts a very long time and is affordable in Thailand. (It's the standard construction method now.) For roofing you can use metal roofing (often the best choice), micro concrete tiles (can still collect roofwater but not so noisy), wood shakes (hard to find) or ferrocement. You can email me at natural houses [at] g mail dot com for further details.
Your building methods are astoundingly simple and effective – they just make sense. I live in Thailand and I want to build an earth bag roundhouse, a larger one that the 177 sq ft that you built here. I'd be interested to know where in Thailand you built the round house? Also, and more to the point, your mention of the materials being $11.50 per square foot was that the price in Thailand?
Thanks
Peter McLaren. Udon Thani
naturalhouses [at] gmail dot com
This is more of a concern than conventional buildings since the plaster is much thicker.
Charmaine Slade
Natural Building Blog -- see our FAQ page and use the built-in search engine
EarthbagBuilding.com
Step-by-Step Earthbag Building Instructable
Do you have any tips for using this method for building outdoor retaining walls? I'd like to build a wall up to 1 metre high. Would it need reinforcing, or to be sloped back into the bank? What about the inside of the wall, would that need to be rendered so as to keep water out and protect the plastic of the bags from deteriorating? We are in a frost-free area. Thanks
Here's one example: http://naturalbuildingblog.com/green-retaining-walls/
This topic is also covered in my Earthbag Building Guide. In general, you want to step the earthbags slightly toward the hillside. Make sure you include adequate drainage so water doesn't build up behind the wall. Sand or gravel in the bags works best.
Leigh
Leigh
It is easy to patch if there is a problem.
Decorative tile is great. It's an excellent choice, especially around windows and countertops and bath areas. I just posted an article the other day about accent tile on our blog. (Just basic info to introduce the concept.)
http://naturalbuildingblog.com/accent-tile/
Leigh
Raise the building site above flood stage. We did this by dumping truckloads of road base in 6" layers and driving a truck back and forth over the top in opposite directions.
It's also less expensive than concrete block and super strong. I suggest building roundhouses in rainy, hurricane prone areas. Domes would also resist the wind, but they're harder to protect against leaks.
Earthbag is very similar to rammed earth. Instead of building expensive wooden forms, the bags work as a form to hold the shape. Google ancient rammed earth and you'll learn how some of these structures have lasted hundreds and sometimes thousands of years.
i am also in the dominican republic, and would like to know if you actually went forward with your idea of building with earthen bags
There's no limit to the lifespan if you maintain the building. Compressed earth structures can last thousands of years. You can make them earthquake and hurricane resistant if you build correctly (roof tie-downs, plaster mesh, etc.).
http://www.earthbagbuilding.com/resources.htm
You can also use Google to find local companies. Search for "sand bags".
Elsewhere where you mentioned the Fechin house here in Taos and working with Habitiat for Humanity and I wondered if you had links to past or current projects in New Mexico with earthenbag construction. I volunteer at a museum here - a hacienda built in 1804 - adobe and earthen treated floors and have friends who as children helped build family homes making their own blocks over a 3 year time span -- the earthenbag technique is MUCH faster. Thanks. .
Earthbag is faster than adobe. It's also stronger and should last even longer. It's very similar to rammed earth that's been shown to last for hundreds of years.
http://earthbagbuilding.wordpress.com/2010/12/14/ancient-rammed-earth-structures/
There are lots of earthbag structures in New Mexico and other parts of the southwest US.
i am thinking of getting a bit of practice by using the technique for some walls in the garden and was just wondering if the earthen plaster you used for the interior walls would be suitable for exterior wall covering too, is it paintable maybe. i am in uk so would have to survive cold and wet winters
Specifically this would be applied to a small round house (perhaps a bit larger than the one pictured) with a stone foundation, in NY, U.S., in the Catskills/Mid-Hudson area (read: "pretty darned wet, but not Oregon, with hot-ish Summers and pretty cold Winters").
Just wonderin'.
http://www.instructables.com/id/How-to-Build-an-Insulated-Earthbag-House/