Win a copy of Grocery Story this week in the City Repair forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • r ranson
  • Nicole Alderman
  • Anne Miller
stewards:
  • Mike Jay
  • paul wheaton
  • Joseph Lofthouse
garden masters:
  • Joylynn Hardesty
  • Steve Thorn
  • James Freyr
  • Greg Martin
  • Dave Burton
gardeners:
  • Carla Burke
  • Pearl Sutton
  • Dan Boone

Could you use earthbag as the walls in a WOFATI ?

 
Posts: 74
51
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
So I'm wondering if earth bag walls could be used to hold up the roof in an earth sheltered, WOFATI style building.

I'm imagining a series of horseshoe shapped rooms like they use in the earthships designs but instead of stacked and packed tires using earth bags to construct the walls. Then using the large umbrella of the WOFATI design to keep the bag walls, roof and surrounding earth dry.

Do you think that the walls would be strong enough to support the burried roof and the weight of all that earth? And this would be in an area that gets about 12 inches of snow a year.

I could use the extra large bags (24" wide) or double the walls and make them two bag widths thick and tie them together with barbed wire on each layer.

Thanks !
 
pollinator
Posts: 148
37
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Penny McLoughlin wrote:So I'm wondering if earth bag walls could be used to hold up the roof in an earth sheltered, WOFATI style building.

I'm imagining a series of horseshoe shapped rooms like they use in the earthships designs but instead of stacked and packed tires using earth bags to construct the walls. Then using the large umbrella of the WOFATI design to keep the bag walls, roof and surrounding earth dry.

Do you think that the walls would be strong enough to support the burried roof and the weight of all that earth? And this would be in an area that gets about 12 inches of snow a year.

I could use the extra large bags (24" wide) or double the walls and make them two bag widths thick and tie them together with barbed wire on each layer.

Thanks !



Hi, Penny.

That sounds pretty sketchy to me.

It's not the snow that concerns me. Soil moves. This is why you see kazillion-dollar projects to construct "bearing walls" in cities. To keep earth from moving, and the neighborhood from running down hill.

If you consider holding objects in your hand, like an apple or a glass of water or a stone, the weight of soil inch for inch is almost unimaginable. You can knock someone completely to the ground with a bucket of earth. When it rains (or snows), even this mass increases--and begins to move.

Wofati and other "underground" structures are, essentially, a "retaining wall" on two or more sides that enclose a three-dimensional object. The parts that are in contact with earth are (while made of a half dozen different materials) monolithic in nature. This means it is one solid piece of something. A wooden beam is monolithic. A concrete wall is monolithic. Welded steel frame construction is monolithic. An unbroken eggshell is also monolithic (and an incredible feat of engineering).

All the support systems for these structures have a few things in common: they are really really stiff, and big, bad, heavy-ass construction. The better in-ground homes are even anchored to the ground in some reliable way to maintain orientation (to prevent shift, or roll), such as slab, or deep set columns, or legs of I-beam deep below the structure, past what is called the frost line (the depth at which no freezing takes place--ever).

You'll want to choose a material that doesn't lose strength if it gets wet--so crackers, cheese, and rammed earth are all unsafe choices for this job.

One last thing and then I'll shut up.

A curved plane is geometrically far stronger than a flat plane. Try this yourself with a playing card. Hold it flat on the two closer edges, and squeeze. It buckles easily. Now bend the top edges toward each other slightly, like a Plains Indian bow--you will notice some tension. Now try squeezing the two closer edges. You might almost have to hurt yourself to get that card to crush.

The strain (of any kind: tornado, soil shift, purple dragons, whatever) is far more likely to disrupt a flat wall, all other factors held constant. If you build a curved wall, it is inherently more resistent, to everything--with exactly the same material, and exactly the same cost.

 
steward
Posts: 4609
Location: Northern WI (zone 4)
1174
hunting trees books food preservation solar woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Good question Penny!  I don't know but I think it seems reasonable that they could work.  I'd do some reading in some of the earth bag books that are out there to see if they touch on the subject.  I'm pretty sure someone's used them underground in a close enough application to what you want to do.

Here are the My Little Homestead youtubers who made a circular underground music studio.  They're possibly drier than you and the structure is a circle which would be stronger.  But you get the idea:
 
Penny McLoughlin
Posts: 74
51
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Yes, I've been reading several earthbag books, a couple of strawbale books and one about earthships too.

I can understand the concern about the bags getting wet after they're in place and them becoming structurally compromised. That's actually why I thought that having them under a WOFATI type "umbrella" would be a really good thing. Although the superado builders have had floodng in their structures without loss of integrity.

I know that they have made two story round earthbag buildings but I don't know of any two story earthships style buildings. At least not where the bottom story supports the top one rather than a design stepped into a hill side.

Does anyone know how a second story compares weight-wise with a WOFATI style roof?
 
If you live in a cold climate and on the grid, incandescent light can use less energy than LED. Tiny ad:
Food Forest Card Game - Game Forum
https://permies.com/t/61704/Food-Forest-Card-Game-Game
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!