Techniques
Filling bags:
Having two
people - one holding the bag open, the other filling it
with a shovel or a bucket - works, but it's slow,
ridiculously messy, and frustrating. If you're working by
yourself with a shovel in one hand and a bag in the other,
it's next to impossible. You're far better off developing
a system and setting up a smooth & efficient
production line to keep your bags moving.
There are a variety of
approaches, which we'll briefly touch on. All of these can
be done by one person.
- We
use
a wooden stand and a cut-off inverted traffic cone as a
funnel. One person holds a bag up over the open end of
the cone, while the other dumps the fill material from a
five-gallon bucket. A third person uses a press (eg, a
toilet plunger) to force the wet fill down into the bag.
Depending on how ambitious we feel, three people can
crank out up to 50 bags an hour. One person can use
this, though your production might be closer to 10 bags
per hour (still, 100 bags in a 10-hour day isn't bad).
- On pages 221-224 of their book Earthbag Building, Kaki
Hunter and Donald Kiffmeyer describe how to construct a
folding metal bag stand out of thick, flat metal stock.
Similar to the frame of some laundry hampers, it holds a
bag open & can be used by one or two people. image
- Another contraption which looks brilliant (fills six
bags at once; we haven't tried it yet) was designed by
River Oak Ranch in Fargo, ND and featured on the website
instructables.com.
You can see the step-by-step instructions and view
a video of it in action here.
Most bags come with
tie strings attached. In the case of building (if the bags
are going to be plastered over), you generally don't need
to tie them. You
can just give the neck a twist, fold it under, and butt
this end of the bag securely against the sewn end of the
adjoining bag.
If you want or need to secure your bags, you can use the
ties - though they're often flimsy & a nuisance. We
prefer to use zip ties or wire ties.
Laying bags:
Grab bag by neck with
one hand & grab the seam on the bottom of the filled
bag with the other hand. Invert the bag, letting the
fill run down towards tied-off neck. Shake bag,
distributing dirt uniformally.
1.) Fold top of
bag under & lay in place (butting this end up against
the seam edge of previous bag).
2.) Give bag a
good shaking to ensure even distribution of dirt (bag
should be roughly rectangular).
3.) Continue
laying bags, using tamper every 3-4 laid bags &
checking your work with a level.
Part of what makes
this fun is that this is an organic process. Shaking
& sorting & patting your dirtbags is something
that comes easy. You'll quickly master an almost
intuitive ability to make corrections when irregularities
pop up. Once it "feels" right, start
tamping and use
your levels. If things start getting wanky, you can use
your tamper to make corrections - whack a little more
here, a little less there, and using it laterally
(horizontally) to even up the face of it.
Doors
& windows:
Doors will need to
have a frame. You'll prop this in place (use your level!)
and then, as each course meets the frame, you'll tamp the
bags securely. For additional strength, you can drive
nails or screws into the sides of the frame to twist the
courses' barbed wire around, or incorporate gringo blocks
(see "getting started"). As you work your way up, check
the door to make sure the frame isn't askew and causing
your door to bind - you don't want to have to undo
everything & start again. When the sides of the frame
are bagged in, you'll add a load-bearing lintel to the top
of the door's frame and then stack & tamp your bags
across the top of this.
Conventional windows (that is, windows that open) will
usually come with a frame. You may want to insert a load
bearing sill (wider than the window) where your window
will go. This sill, if it projects out far enough, will
make a shelf that you'll be glad to have when you move in.
Then install & pack your bags around it as described
above. Finish up with header on top, and finish your
bagging.
Windows without a frame need not require a sill or a
header, if
they're strong enough to sustain the weight of the bags on
top. If they're round, you can leave one bag out of your
course, insert your window, then pack your bags around it
with each successive course. You'll find this easier to do
if you only use 1/2-filled bags so you can smush them into
shape.
More:
Barbed wire:
As mentioned elsewhere, start using 12" - 14" wire strips
between bags if your wall or structure is above 3 feet. We
recommend two strips of barbed wire per bag. After
laying a bag, firmly twist the bag to "seat" the barbs
before moving on.
Buttressing:
Think of these as reinforcing pillars every 6-10 feet or so
along the length of a wall. Don't underestimate the
importance of buttressing long, high walls, and don't
count on a plaster / stucco overlay to give such a wall the
significant structural strength you'll want when the
kids are climbing on it. Rule of thumb for buttresses is 6"
perpendicular to wall for every foot of wall height.
Burlap bags:
Using these bags requires working quickly, under dry
conditions, and then plastering them as soon as possible.
You should build a stem wall (bags filled with gravel,
etc.) to raise them above ground level to prevent moisture
from wicking up.
Leveling: We can't emphasize
this enough. Frequently check your work in all 3 dimensions.
Earthbags
are something you don't want to have to take apart &
reassemble (especially if you're using barbed wire), so get
it right the first time. Is your course running straight
(end to end), or starting to drift? Is the course the same
height at both ends? Are the bags starting to slant inward
(towards you) or outward (away from you)?
Check the wall itself periodically with a beam level to see
if it's starting to cant towards or away from you. If
you stay on top of it, you can self-correct with the next
bag. We talk about this a little more on the getting
started page. Of course, if you want undulations or
sinuousity, that's something different. The point is to pay
attention & make sure that things are going as you
intended.
Bigger projects:
Some people spread the work on bigger structures over
a year or two, which also allows spreading the cost out.
You should consider it mandatory to either tarp & secure
your work as you go along, or slap some base plaster on your
bags to protect them. Because our New Mexico sun &
altitude are so hard on polypropylene bags, they will start
to disintegrate after a few months. Strong winds carry
abrasive sand as well, and can do a number on your hard
work. Burlap bags are equally prone to weather, as well as
dampness, insects, soil bacteria, and critters. So, again,
keep your work covered.
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