How To Ready A Homesite For Earthbag Walls

There are quite a few websites that discuss building an earthbag home. Considering our specific situation, that became the obvious choice for our acreage in Cochise County, Arizona, a considerably different environment from the survival cabin country in Montana. But online research also convinced me of something else: While a few true pioneers have built innovative dwellings using the soil available wherever the building was to be erected, most writers have simply copied the work of said pioneers and repeated it as gospel.

Not here, folks. I'm willing to learn, but just because this or that guru done said it don't make it so in my book. Or words to that effect. For example, one commonly touted technique for preparing the ground beneath earthbag walls involves layers of gravel and all sorts of "necessary" steps including ramming or packing the earth as you go. I rejected that. The soil here is very high in clay content with a fair amount of caliche as part of Mother Nature's mix. Packing the stuff artificially is a waste of time and effort. Both our camp trailer and the semi trailer we use for storage have been perched on concrete blocks for the past six months, a span of time which included the monsoon season. Those blocks were just ker-plunked down on the ground, the full weight of the trailers have been pressing down ever since, and yet not one of those mini-pillars has settled into the ground to any noticeable extent.

In other words, our ground comes "pre-pressed".

With that in mind, I decided the home's perimeter foundation would be composed of nothing more than a single row of four inch thick concrete blocks available from any building materials store, no fancy preparation, just set them down on level ground and get to work raising the walls. Even with that level of simplicity, though, two underground lines needed to be in place before the blocks were placed. One was the incoming water line, and the other was the outgoing sewer line. On October 10, it looked highly likely that I'd be able to finish both lines, fill in both trenches, and begin placing blocks before sunset.

Enter Murphy's Law.

Having now run close to 500 feet of one inch PVC water pipe from the corner of our property to the water tower and from there to the homesite, I'm getting pretty comfortable with that stuff. An hour after starting today, the incoming cold water line was completed and stubbed off with a standpipe and valve close to the center of our future home. Now for the sewer line, which ought to be a similarly simple piece of cake.

Except...I'd gotten the wrong piping for the job and ended up making two runs to Home Depot that should have been unnecessary and which burned a lot of daylight. Once I had the right ABS sewer pipe, however, things went smoothly.

First, I'd decided to use three inch sewer line rather than four inch. Either is acceptable, but three inch saves some money in materials and also takes less water to "flush clean". The four inch septic tank inlet thus received a reducer, followed by 30 feet of three inch line, an elbow, and a cap to keep out dust and curious critters. This completed the pipe laying per se, but it's crucial to get an even "drop" or slope from things like toilets all the way out to the tank. This was accomplished by blocking the pipe at the desired height and checking results with a level.

Once that was checked out with a flow test--simply a five gallon jug of water dumped down the hole as fast as the container would empty--it was time to shovel in enough dirt to steady the blocking for the night. This last was done by flashlight. The wooden blocks will be left in place to rot; it's just easier that way.

Special flow test note: The water disappeared down the "drain" lickety-split, worked beautifully, no obvious leaks. We're good to go.

Bright and early in the morning, just as I was finishing the burial of both plumbing lines, a white pickup drove into the yard, piloted by Anthony with Zach riding shotgun. Zach is Pam's son, he had the day off, and he'd decided to visit his Mom...and see how our construction project was progressing. It was "all good" (as they say) and even topped off by a third visitor: Anthony brought Pam a little critter he'd just missed running over, a baby horned lizard.

Zach taught us several things about this species that we hadn't known. For one thing, they actually like to be gently stroked! He demonstrated with the little guy, and the tiny lizard just sat there quietly on the ground, soaking up all the attention without a hint of protest. This type of reptile is one that will squirt blood at you from its eyes if it's too scared--no, it's true!--but clearly Zach was not scaring it in the least.

Lots and lots of online writers go into great detail about preparing the foundation for an earthbag home. Pretty much without exception, however, each way of getting it done involves a sizeable drawback...either by being costly or being a pain in the tail to accomplish.

One simple way of going about it is to put down a nice, level concrete pad and build the home on top of that. This does have advantages: The base is an easy platform on which to work, for example, and it won't leak or let ground dwelling critters like adventurous moles come up in the middle of the living room. On the flip side, professionally poured concrete is not cheap, it's not as effective as Mother Earth when it comes to thermal mass, and it's anything but flexible (as a slab) when it comes to working with add-on plumbing. So I didn't want to go there.

Earthen flooring--not just plain ol' dirt, but the fancified modern day version--sounded great until enough in-depth reading made a number of drawbacks abundantly clear. The first drawback is the sheer amount of time and labor needed to properly finish even a small living space, and ours (at nearly 1100 square feet inside the walls) is not really tiny. Worse than that was the cost of sealing the earth at the end with gallons and gallons and gallons of linseed oil which amounts to a sizeable expense. Finally, the stuff is too soft and requires a bit of maintenance here and there to repair dings and dents, not to mention renewing the expensive linseed oil every few years. So that didn't seem right, and yet I definitely wanted to say close to the planet on this one. What to do?

In the end, I figured out an unbelievably simple flooring system that won't be able to prove itself until I've installed it. All that needs to be said for now is that I won't be touching or covering the dirt in any way until the walls are up and the roof is in place.

Which left the perimeter. With earth bags being a flexible material, the base beneath them did not have to be exactly level: the bags can be adjusted "on the fly" to level out when the desired height is reached. This was important because our septic system contractor also leveled the ground, but only approximately. He did use a torpedo level to check his work, but his only equipment amounted to an old backhoe with a front end loader. No fine tuning, no raking, no power tamping to get things "just right". Plus the fact that he had to leave trenches open on two sides for me to add plumbing lines.

All of which left that concrete block perimeter idea sounding better and better. I didn't yet have the bags on hand and wasn't quite sure just how wide they would be when filled, but the base would be an even sixteen inches and that seemed like it would certainly be enough.

 It was. When the bags did arrive, they checked out (when filled) at precisely eleven inches in width. No problem.

Total cost of concrete foundation: Just under $550.

The first side to receive foundation blocks, the south side, was/is also the least level side. As a result, that side looks more than a bit "wavy" as though a drunken architect had designed the whole thing. The truth, however, is not nearly so grim. Firstly, the wave is only in the vertical plane.

Huh?

What I'm saying is, the side "edge" is absolutely clean and straight to within an eighth of an inch. That is crucial. When it comes to building the roof, I'll be using premanufactured trusses built by a local truss company. Their prices are impressively reasonable, they can produce the design I want, and nothing else makes as much sense. But trusses do require the bearing walls--in this case the north and south walls--to be as close to "perfect" as possible.

Additionally, the "wave" isn't nearly as severe as the photos make it seem. What looks like a real roller coaster does not, in fact, vary in elevation by more than an inch from end to end.

So far, so good.

Pam mentioned today that my construction approach looked "strange" in that she'd never seen a home built where the doors were installed before the walls were raised. She's right; that's not the usual sequence of events. However, in this case it is essential. The 2" x 12" casements surrounding the prehung steel doors (bought on sale at Lowe's last month) need to be in place so that the earthbags can butt up against them as the walls rise level by level. With the doors already in place, it becomes a simple thing to check them regularly: Do they still swing open and closed easily after that last round of bags? We've all seen homes in which the framing was too warped for the door to operate properly; who needs that?

The first step was to open one of the doors just to see how it looked. At that point, a photo became a necessity in order to document The Door To Nowhere! Okay, technically the door to my pile of tires from the semi trailer, but you get the point.

Since I knowingly started with a loose-block foundation system rather than (for example) a completely level concrete pad, the large square blocks supporting the door frame had to be "tweaked" a bit. Eyeball the thing, check with the level, lift the edge of a block, brush a little dirt here or there, repeat the process until satisfaction is achieved. Then cut a piece of 2" x 12" lumber the exact width of the prehung door, check the level again using the board, nail the board in place using fluted nails suitable for concrete, and call your wife to steady the door while you tack on a brace consisting of a ten foot 2" x 4".

Finishing up everything on that front door took approximately 3.5 hours of slow, steady, careful labor, each cut being made (for instance) with a handsaw. Then a meal break, and I was ready to whip out the second one, the back door, in a New York minute. Oh, and I did! I did! I bragged about my speed and precision to my wife! It had taken a short time, only a very short time, and that door was right up there on that nailed-down framing lumber and firmly braced.

Then....

Then I suddenly realized the rain would be dripping down from the sill. I had the door nicely secured and totally upside down.

Oops.

Even so, once I could control my own laughter--Pam was too polite to even snicker--it didn't really take that long. Start to finish for second door installation: 1.85 hours. Looking good.

Now for lots of barbed wire, dirt shoveling, bag sewing, and wall building.....