How To Protect Earthbag Walls

When it comes to earthbag walls, their greatest enemy is that good ol' sun. UV (ultraviolet) rays from our blazing star can absolutely destroy the polyethylene sandbags used to contain fifty pounds of dirt at a time. Long before forming a clear picture of how I wanted to build our new home, that tidbit of information gave me pause. More than anything else, the methods suggested for preventing UV destruction of every bag in the wall gave me pause!

Especially one method. Cover the walls with tarps while you're building, many a website bugled. It's the simplest way to go and the best.

Say what? What about all those other sites with photo after photo of completed buildings where the construction is finished and the bags are still fully and obviously exposed to the elements? What about those, huh? Huh?

Given the likelihood that UV rays did truly constitute a long term threat, the use of tarps--which some sites did illustrate with photos--was still an absolutely ridiculous concept. True, no builders want to see their bags disintegrate and their hard work suddenly crumble into piles of yuck on the ground where there used to be walls. Also true, some photos did show tarps effectively in place, especially over small dome projects.

But here at New Moon Ranch? (Okay, so it's only four acres. It's my mortgage payment; I can call it a ranch if I want to call it a ranch, all right?)

This building project is square, 36 feet to a side. That's 144 linear feet. Toward the end of the project, when the walls are (for example) 6 feet high, not even a 12 foot tarp will reach up one side, over, and down the other side. Cover the entire project, only uncovering one side at a time to work on it, and you're talking about a whole lotta tarping goin' on. Even the cost of the tarps was unacceptable, and that's before even considering the wind. Our choice of power production out here is a wind turbine--yet to be constructed, but enough to make the point: Tarp this thing fully, and you'd be spending more time and money chasing and securing the tarps than you would filling earthbags. Hunh-uh! No way!

So...what to do? Well, the bags come with a "UV resistance rating" number. That number is a statement of how long the bags should be able to remain fully functional under a blazing sun. Our bags came, quite simply, from the bag supplier with the best price that could be found online. Their UV resistance, according to the website, was listed at 1600 hours. A mild shock occurred when I ordered the second and final batch of bags. That order included a much smaller box which held a single bundle of 100 bags...and the box was clearly labeled at 1200 hours, a whole bunch less than the online listing. Probably a typo, but in the end it didn't matter. I'd already allowed a healthy margin for error, figuring to protect every bag from the sun by the time it had been exposed for one month. Since at this time of year, even in southeastern Arizona, we get a touch less than 12 hours of sunshine per day, that meant the bags should be "safe" for 100 days.

Thus, no harm, no foul.

The first bags were filled and placed on October 15. Tomorrow is November 11, and the first six layers of bags will be covered. How? The eventual exterior finish will be concrete stucco. It's not time to tackle the stucco itself, but why not do the prep work? Home Depot had the best price on chicken wire stucco furring lathe with tarpaper backing--and that ol' tried and true tarpaper is not about to let those nasty ol' UV rays touch the bags in its tender, loving care.

It turned out that expecting to be able to apply the stucco furring all the way around the "fort" on both the outside and inside perimeters in just a couple of days...was a tad overly optimistic. It's Sunday night, four full days after this Hub was begun, and only the outside perimeter has been covered. Reasons for the slowdown:

1. Personal errands that I never saw coming but which couldn't be ignored.

2. The sheer number and diversity of the building supplies needed for both the tarpaper task and for framing the windows, which will constitute the next portion of the project.

3. Breakdown of my digital camera. The camera had to be replaced and the new unit "learned" before photos could be taken for this part of the Hub.

4. Earthbag staples. Let's talk about those....

You won't find these at Home Depot. One online writer mentioned using homemade wire staples to secure stucco netting to his earthbag walls. These are roughly six to seven inches in length (precision in length being unimportant...as long as they're all fairly long). Said writer also mentioned that he used the staples "sparingly". I don't. In fact, I don't have a clue how anyone could get by without using quite a few. In my case, a 36 foot length of wall requires at least 90 staples (at bare minimum) to hold the tarpaper/wire relatively flat to the bags. But they do work, and the result seems to be worth the effort.

What I did find at Home Depot (after refusing to buy from Lowe's, another Hub entirely) were 100 foot rolls of 14 gauge galvanized wire which seemed like it might do the trick. Once made into staples, the wire penetrates the earthbags fairly easily--as long as one hand is used to "reinforce" the staple while the side of a pair of fencing pliers is used to tap the staple into the dirt wall using very little force. A brisk tap will bend the staple instantly, as will encountering a hard dirt clod or rock within a bag. If an obstacle is resisting the wire, it's a simple enough matter to pull out the staple--the holes are small enough that dirt does not start falling out--and finding another spot to tap it into place. Admittedly, these are awfully thin, flexible staples. Baling wire might be available locally in a slightly heavier gauge and produce a stouter staple, though the downside would obviously be a bit more difficulty in shaping the staple in the first place.

When it comes to making your own long staples--because no one seems to have them available commercially--patience is the watchword. A roll of wire is first cut into appropriate lengths. Because I roughly measure that length by folding the end of the roll back across the palm of my hand and allowing a "tail" reach a length of at least six inches, each piece comes out looking very much like the stylized "Christian fish" symbol we see all across America. (I'm not a Christian, but the symbology does seem striking).

That cutting process goes quickly enough, but then each piece of wire has to be shaped by hand into sort of a "long bobby pin". Converting 100 feet of rolled wire into 90 to 95 staples takes me between two and three hours.

Patience required.

Stucco texts consistently advise regarding the necessity to allow for stucco shrinkage as the concrete product cures after application. This is accomplished by using metal "expansion control joints" sold at any building materials supply store. Against all recommendations, I decided to run the tarpaper/wire stucco netting right over the top of the metal. That wouldn't be the brightest thing to do when it comes time to actually start the stucco work--the control joints are there to separate sections into no more than 144 square feet each.

But it looks like it will be months--possibly as many as six of them--before I can get to that. Stucco needs to avoid dropping below forty degrees until it's had time to cure, and even in southern Arizona, that's a problem during the winter months. Tonight's temperature here, for example, is likely to drop to around 25 degrees or a bit less. It could be as late as May before it's safe to "slap stucco". In the meantime, leaving the tarpaper more or less "intact" for now will allow it to provide excellent protection against UV rays...and when it's time to let the joints truly do what they're designed to do, I'll get creative.

Eh?

Oh, no big. The plan is to simply slice the paper down the length of the center of each joint (snipping the "chicken wire" apart as I go) so that the two sections (on either side of the joint) can then go ahead and shrink with the stucco as it dries.

Despite the slow pace, the outside wall perimeter did get fully covered as of late this afternoon. Except for the top 1 1/2 earthbag rows, that is. Those began "seeing daylight" on or around November 6, so they have plenty of time left to be safely UV resistant.

According to their 1200 hour rating, anyway.

More about the expansion control joints: Since the wall height is only about halfway there, I cut the store-bought eight foot sections into shorter pieces in order to avoid having them waving in the air for months like fishing rods with trout on the line. The upper pieces, when added later, will simply have to sit right down on the tops of those already in place. Making clean connections between them will be slightly tricky but should be manageable.

Mostly I'd love to know if any reader(s) are versed in the best way(s) to hide those joints after the main stucco sections are nicely cured but before painting. There must be known methods. Otherwise, every large stucco wall in the country would have obvious, light reflecting, hideous metal strips showing...and I'm pretty sure they don't.

On the other hand, I've not so far found been able to find out how that's usually done. Sure, I could seek out a few local contractors and pick their brains, but hey. A guy actually asking directions? Heresy!

Before I could start work on the home today, a trip to the Post Office (some 15 miles away) had to be made. When I pulled into the parking lot, I noticed for the first time that the building has a stucco exterior. Close examination uncovered the expansion control joints. Except for blending in with the rest of the wall thanks to a coat of paint, they looked pretty much like the ones I bought at Home Depot. Huh. That's all they have covering the metal, just paint. Maybe that's the smart way, maybe not. 100,000 stucco contractors can't be right...can they?

One other noticeable fact about that stucco wall is that the edges where the stucco and the control joints come together is clearly cracked. Top to bottom, every single one. We'll eventually see if I can do better...or not.

First, however, I'd made a quick stop at our local feed store, San Pedro Feed and Hardware. Did they have baling wire? As it turned out, no, they don't stock the big hundred pound rolls of wire I remember using in my Dad's baler on the ranch in Montana. On the other hand, they did have little rolls of wire that might work. 330 feet in length, but only 16 gauge. Since I've been using 14 gauge and that was barely strong enough to use for staples, was the smaller 16 gauge stuff even worth a try? The final decision was: Why not? Price, you see. $5.99 for 330 feet versus $6.27 for 100 feet of the 14 gauge galvanized version. No galvanizing on the smaller wire, so it will rust easily, but so what? It's only there to pin the tarpaper in place for a few months, after which it will be permanently protected from the elements.

Scientific experimentation resulted in the following discoveries:

1. The 16 gauge can be used as a long staple. Since it's so thin and therefore quite flexible, the way to get it to penetrate the tarpaper and then the earthbag is to wear leather gloves and use both hands rather than any sort of pounding tool. The side of a pair of fencing pliers can be used to hammer the staple in for the last inch or so, but that's about it.

2. Being so thin, it's actually easier to push the 16 gauge wire into the wall than it is to tap the 14 gauge product into place. If it hits a clod or rock, it does bend immediately, but there is always another workable spot for "staple entry", so that's not really a big deal.

3. In comparison to the "grind" of making staples from the 14 gauge, the lighter wire is an absolute breeze. Since it's so wimpy, sidecutters (diagonal cutting pliers) are more than enough to snip it, and they're easier/quicker to handle than the larger fencing pliers. Result: Speed. But the actual shaping-by-hand of the cut lengths into working staples is where this wire truly excels. Remember that bit about 90-95 finished staples requiring between two to three hours of labor with the 14 gauge wire? Get this:

100 lengths of 16 gauge wire cut, elapsed time...................9 minutes

100 cut lengths shaped into finished staples.....................34 minutes

100 staples from rolled wire to useable staples, total........43 minutes

Less than one third of the time and a few more staples to boot! I vote for that!

It seemed like getting the tarpaper and wire in place to cover the inside of the earthbag walls took, oh, just forever.... Turns out that "forever" is roughly 48 hours--who knew?  From cutting open the first row of stucco netting to driving the final staple for both insides and outsides of the walls took exactly one week.   Felt like a year or two.  Impatient?  Who, me?

Anyway, with that much done, it's now time to get the window casements built and placed.

On that topic, I seem to have a Supervisor and Critic: Pam's special bunkmate, Kitten Precious, who wants to be sure the finished home will have window shelves for her Outside Viewing Pleasure.

No problem, Kitten. I promise. Just a dozen more Hubs or so, and we'll all move right in....