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Posts Tagged ‘scoria’


Please document your earthbag project to share with others. Festismr’s YouTube channel has 17 videos on building a scoria bag house.

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Yogi Farm is planning to build earthbag roundhouses like this one with scoria bags.

Yogi Farm is planning to build earthbag roundhouses like this one with scoria bags.


“We are a tribal, egalitarian community focused on living in harmony with the Earth, practicing yoga and meditation, sharing a raw vegan lifestyle, and creating a permaculture farm with lush and abundant food forests in a warm tropical environment.

We are in the process of acquiring a piece of land in the Puna District of the Big Island, Hawai’i, to create a permaculture farm, wellness center and close-knit community of adults and children. This will be a raw-vegan, off-grid community, focusing on simple and synchronized living, yoga & meditation, egalitarianism, permaculture, natural building, beekeeping, natural healing, and personal and planetary transformation.

We are planning to build ‘scoria bag’ roundhouses – circular structures using a variation of the earthbag building technique, as the initial structures to establish and sustain our community and farm. Scoria is another word for volcanic cinder, which is widely available and inexpensive here. This building method comes highly recommended by an earthbag building expert who we are consulting with.

Our main common house and all individual dwellings at Yogi Farm will be similar in design, scaled appropriately depending on need, quick to build, inexpensive, and very attractive and sturdy. This approach is not only simple and elegant, but also in keeping with our egalitarian principles. Our approach is to quickly and easily meet our needs in terms of structures and dwellings, and then bring our full attention to the land, soil, food production, etc., right in the very beginning.

Like earthbag, scoria bag is very quick to construct – actually, even quicker. The main differences with scoria are: 1) it is much more insulative than typical earthbag, 2) there is less thermal mass effect, 3) it is lightweight and easy to work with, and 4) it requires some reinforcing. Hence, scoria bag is a great material, and reinforcing is very straightforward using ‘external pinning’ with rebar [or bamboo], and internal rebar driven through the courses of bags.”

Source: Yogi Farm

Tips for building scoria bag roundhouses in hot, humid climates:
– Using Scoria for Earthbag Building (good overview of the benefits of using scoria or pumice)
– Other reinforcing techniques in addition to external pinning (not all methods are necessary – pick and choose accordingly): earthbag benches, buttresses, bond beam (required), barbed wire between courses, mesh on both sides tied together through the wall, poly strapping, tie courses together with baling twine like Kelly Hart’s dome
– Cooling and ventilation tips: build on high ground with breezes, build in the shade and/or in the forest (but not so many trees that breezes are blocked), cathedral ceilings, wide roof overhang 4’ minimum (minimize direct sunlight on walls), windows on all sides, casement windows aligned to capture prevailing breezes and funnel them through the house, tall windows that go up to the bond beam (no lintels required), air space between the bond beam and roof, screened transom above door, additional plants on the side facing the hot afternoon sun (trellis, more trees, vines). We did all these things and our roundhouse is 8 degrees C (15 F) cooler inside than outside, and the inside temperature stays nearly the same all the time.
Faster, easier compression ring than the one I used
– Our earthbag roundhouse photos on Picasa
– Free roundhouse Instructable with detailed building instructions
– More earthbag scoria tips at Earthbag Scoria Casita and Festimir’s YouTube Channel

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Here’s another great project. This small domicile demonstrates how scoria homes are faster and easier to build than bags filled with soil, and more insulating. This doesn’t mean standard soil-filled earthbags are obsolete. There are pros and cons to each system, however, I strongly encourage using scoria bags (or pumice or other suitable lightweight fill material) if there’s an affordable supply. Thanks to Joe for taking the time to document everything and share what you’ve learned.

“Hi Owen. Wanted to let you know I just uploaded 10 new videos on my YouTube site. One is a portable solar water pump, all others are on our earthbag building.

I’ve been keeping close track of our labor and expenses. We’ve only been able to work on the building for 5-7 days at a time, several times a year so it seems to be taking a very long time. However, I added up our hours so far and was pleasantly surprised. To get to our 8′ height, ready for the bond beam, including digging the foundation, laying bags, framing and providing lintels for several windows / door openings, putting in a main beam with floor joists for loft:
392 RUNNING TOTAL HOURS
392 hours is only 9.8 40 hour weeks. If you could extrapolate this to a crew of 4 this would be about 2 ½ weeks!!!

Thanks once again for your advice, and thanks to you and Kelly for keeping up your wonderful earthbag sites. Feel free to use this info.”
Joe

You can watch all his videos at Festimr’s Channel. (Required viewing for serious earthbaggers.)

Related:
Using Scoria for Earthbag Building (Good overview of the benefits of using scoria or pumice.)

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Earthquake and hurricane resistant geopolymer ferrocement cage filled with insulating material such as scoria or pumicecrete

Earthquake and hurricane resistant geopolymer ferrocement cage filled with insulating material such as scoria or pumicecrete


Dustin: I live in Florida where few domestic buildings last more than 50 years because of hurricanes. I explored the Monolithic Dome for quite some time. They have stood the test of direct hits by very powerful hurricanes that leveled the entire neighborhood; except the dome. The dome is the only sensible structure here. No other structural shape has ever withstood a Category 5+ Hurricane. EVER. Earthbag Domes seem capable of the same, or close. How can I finish an earthbag dome that won’t erode away in Florida storms?

Owen: A lot of people have been impacted by hurricanes, tornadoes and earthquakes. This is something I’ve been working on for years due to the seriousness of the problem. My article on Disaster Resistant Earthbag Housing provides some background information on this issue.

Kelly Hart, Patti Stouter and I collaborated on EarthbagStructures.com as an effort to consolidate information on disaster resistant earthbag structures, especially for developing regions.

The short answer to your question is to use either cement plaster, or preferably plaster the dome with Portland shotcrete or geopolymer shotcrete. Geopolymer is a natural material (essentially man-made stone) that’s stronger than Portland. The incredible benefits of geopolymer prompted me to start the Geopolymer House Blog, which already has over 140 blog posts.

Geopolymer is preferred because it’s stronger and more durable than Portland, although it’s not available everywhere yet and it’s probably more expensive. So fiber reinforced shotcrete would be the next best thing. I recommend ferrocement eyebrows over window and door openings to help keep out blowing rain. See Geopolymer Shotcrete on Reinforced Earthbags.

Another very similar option is to build a double shell ferrocement dome filled with lightweight insulation. Scoria or pumice would work perfectly for fill material in the core. As explained throughout our blogs many times (use the built-in search engine above to read the details), scoria and pumice are fireproof, rot proof, lightweight, insulating and do not attract insects or pests. Earthbags aren’t necessary. You could pump or pour scoria, pumice, perlite, pumicecrte or perlited cement from above directly into the core.

So far no one has built a dome like this as far as I know, even though this building system would create some of the strongest buildings in the world. I’m sure it would work. However, there’s a learning curve to everything and some details would need to be worked out. The end result would be just as strong if not stronger than monolithic concrete domes, and be more durable and more highly insulating. In addition, this design is almost certainly stronger than monolithic domes in seismic areas, because it would more readily flex under extreme loads.

Precision Structural Engineering, Inc. is the pioneer of Reinforced Earthbag Building and the only company at this time that engineers and stamps earthbag plans. They’re also expert in ferrocement and can engineer the ferrocement domes that I’m describing here. They have pre-approved my Earthbag House Plans and provide free quotes. They can get code approval in virtually every state as well as many countries.

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Here’s another project in New Mexico. You can follow the progress on festismr’s Channel. The photo below shows where they’re at now.

Earthbag Prototype How-to

Earthbag Prototype How-to

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Halcyon Times Dome Home

Halcyon Times Dome Home


“Three long months… 2,000 sandbags, 4,000 nails for closing the bags, 90 cubic yards of lava rock, 4 miles of barbed wire, -40 lbs. of combined weight-loss & 37 cans of Cattle Drive Chili… we have completed construction of our dome home.”

Halcyon Times blog

Note: They used scoria (lava rock) as fill material.

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Earthbag/Stone Foundations (click to enlarge)

Earthbag/Stone Foundations (click to enlarge)


The most recent issue of The Last Straw journal (#60) has my article about earthbag/stone foundations. The following information is just a short excerpt. You can buy the full length article from The Last Straw. The design outlined here can be used with load-bearing and non load-bearing straw bale walls, earthbag walls, cob, adobe, cordwood and other wide wall building systems. The drawing shown above has been modified to show earthbag walls instead of straw bale walls.

Polypropylene bags come in various sizes. Two common sizes are 18” and 24” wide bags. When 18” bags are stacked on top of 24” bags, there’s a ledge created that can be used to support stonework. (See drawing.)

When filled with gravel, 18” bags are about 15” wide. Filled 24” bags are about 20” wide. That leaves about 4”-5” for stonework. Consider double bagging the foundation (one bag inside another) for extra strength and durability. And, as always, protect the bags from sunlight.

Besides being extremely durable, using stone in a foundation just ‘looks right.’ A combination of stone, earthbags, and scoria as a fill material makes for a high-quality, durable, insulated foundation with many advantages.

You can purchase single issues, subscriptions and back issues from The Last Straw.

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If you’ve been reading our blogs and websites, you’ll often see reference to scoria. Scoria, also known as lava rock, has numerous properties which make it a great building material. The key breakthrough for earthbag building was Kelly Hart’s house made with bags of scoria. His house stays comfortable year round in a very cold climate. This blog post recaps some of the most practical applications of scoria-filled earthbags.

Scoria, a type of lava rock, is excellent for earthbag building.

Scoria, a type of lava rock, is excellent for earthbag building.


Scoria is perfect for superinsulated earthbag walls. It’s low cost, all natural, rot proof, fireproof, doesn’t attract pests, and is lightweight and easy to work with. Anyone can handle bags of lightweight fill material such as scoria by themselves. It’s almost like handling bags of popcorn.

Previous posts have explained how to build insulated earthbag houses with scoria. Insulating Earthbag Walls with Tube Sandbags describes how to use tube sandbags filled with scoria as an outer layer of insulation. Earthbag Building in Cold Climates explains how bags can be sewn to create two compartments – earth in one side and insulation in the other. In extremely cold or extremely hot climates I would fill the bags with 100% insulation (or all earth in a hot climate if insulation wasn’t available).

Earthbag foundations 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 warming), and require no forms or expensive equipment. Scoria-filled bags create a shallow, frost-protected foundation, and therefore eliminate the need for rigid foam insulation and extensive excavation. This one step alone could save you thousands over conventional foundations.

Earthbags are ideal for building greenhouses due to their resistance to moisture damage. When filled with insulation such as perlite or scoria, earthbag walls and foundations enable you to grow plants year-round.

Kelly Hart’s free Dome Building Guide shows step-by-step construction of how to build earthbag domes. His method of using scoria-filled earthbags is the easiest, fastest dome building method that’s been developed so far. Scoria is great for building domes since the aggregates tend to lock together and form stable walls that can withstand high compression loads. Tie courses together with twine for best results.

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