When it comes to building earthbag walls for new home construction, opinions vary. You can find web pages touting the advantages of loose volcanic rock, dirt with the “right” mix of clay, sand, and moisture, even rice hulls. Shouldn’t use topsoil (they say) because vegetation will be included which will later rot.
I call B.S. on a lot of the “information” provided. Not so much in cases where the authors have personally used this or that technique and found it workable. Those are fine. If something worked for you, then it worked for you. No, I call B.S. on those who imply or even state authoritatively that you should not, could not, ever do a this or a that…or that you must do a this or a that. Mix water with the dirt? Yeah? How? Bag by bag? Shovelful by shovelful? Garden hose? Spit on it? Where we live, the earth beneath our feet can go from blowing dust to bog-down slickery slop mud in a heartbeat. Not my idea of a fun game to play.
As for the vegetation issue, okay, allow a thick chunk of root or branch to go into a wall and yes, I can see that when it rots out completely, that might not be good. But “clean the dirt”? Give me a break! Call the plant matter straw and make a brick!
With all that in mind, it made sense to (a) use surface dirt on an “as is” basis, (b) let the moisture content worry about itself, and (c) pick out big chunks like pieces of mesquite branches or roots but ignore the occasional bits of bunchgrass stems. Once the perimeter foundation of concrete blocks had been laid and the entry door casements built, mounted, and braced, it was time to get a-bagging.
Mastering The Barbed Wire
One thing I do agree with most fervently is the use of barbed wire to lock the layers of earthbags together into one cohesive whole. Four point barbed wire, that is; the two point version we used on the Montana ranch where I was raised just wouldn’t be worth the price of the wire. For the first two layers, stakes were driven into the dirt at either end of each side of the house-to-be. Where the door casements interrupted the “flow” of the wire on the east and west sides, staples were hammered directly into the framing lumber.
Filling The Bags
A most important element when it comes to shoveling polpyropylene bags full of dirt, especially when the home is being built by a crew of one, is to come up with a proper bag holder. In this case, a tall five gallon bucket became the base of that holder…but it needed more. This was accomplished by nailing together a bunch of 2″ x 4″ pieces to build up a solid “topper” with an 8″ x 12″ opening down the middle. Then a number of 8d nails were driven partway into the upper inside edge and their heads removed with bolt cutters so that they angled upward with sharp points.
These points serve as “bag snaggers”. They do leave holes in the bag, but it doesn’t matter since the tie-off ribbon closes the neck below those holes. No harm, no foul.
I don’t shovel dirt directly into the bags. Rather, a 4.5 gallon bucket is filled first. This amount, as it turns out, is exactly the right amount to fill a bag as far as it can be filled and still use the tie-off ribbon. If I were to sew the bags shut, as discovered during pre-build experimentation, the bag can hold a bit more dirt…but not enough to make it worth the time and effort it would take to thread a curved needle, do the sewing, etc.
After a while, it became clear that only four of the sharp bag-snagger nails were being used. The others were hammered down flush, saving a lot of nicked skin.
Being a bit of an optimist by nature, I’d hoped against hope to be able to lay one full round of bags in one day’s work–not an eight hour day, since my average in our situation seems to run between six or seven hours as winter begins to speed up sunset, but still. However, half of one round appears to be the pace that works for now. On the higher layers, things will of course get slower.
By the time four layers had been put down, I’d learned a number of things:
1. Every single one inch ball valve I’d purchased from Home Depot leaked, a steady, slow drip that increased over time. Because of that, it became necessary to fix the incoming water line by adding a brass ball valve. That does not leak. Going to get the needed parts did take a little time away from filling earthbags, though. Which didn’t matter, as a cold snap complete with a nasty wind made taking a break a really good idea, anyway.
2. Stakes were not necessary for anchoring the barbed wire layout after the second row of bags was in place. Instead, it was better to simply tuck an end of the wire down over the top corner bag (at each corner), then in betweeen that bag and the one below it. Cleaner, no need for “wire traps” to catch unwary humans, and a savings of something between 500 and 1,000 feet of barbed wire over the course of all those separate layers.
3. Whenever a bit of rain comes along, the walls get stronger. Sometimes dramatically stronger. Theory: All that “moistening the dirt” promoted by some websites is being provided by Mother Nature. The bags are not waterproof. A bit of rain dampens things, and then the earth dries back out and becomes a solid clay-rock wall.
4. The metal “slide” for precison bag placement (promoted by more than one site) sounded like a great idea…until I found I didn’t need it. My eye is good enough; just slam the bag where it looks like it ought to be, and it is where it ought to be. Or close enough to fine tune with no problem, anyway. Must come from stacking all those hay bales as a kid.
Not bad! Not bad at all.