Polypropylene bags are susceptible to UV damage if left exposed to sunlight for more than a few weeks. High intensity sunlight in deserts and at high altitudes is a particular concern. Builders typically use tarps to protect earthbag walls during construction to minimize UV damage and maintain the strength of the bags. But tarps have numerous drawbacks: They blow in the wind, often need readjustment as you work on different parts of the home, and they cost money. This blog post explores ways to eliminate or reduce tarping to save time and money.
One possibility is to coat exterior surfaces of bag walls with latex paint. That’s what Ghost32 used, author of How to Build a House Single Handed, in Hereford, Arizona. Latex paint can often be acquired very inexpensively. Sometimes you can locate mismatched colors or buy it from recycling programs. However, the latex paint may hinder bonding of stucco. Please send us your comments on this. Ideally there would be more testing before this method is put into widespread use.
Nolan Scheid of MortarSprayer.com suggests adding a skim coat of what will be used as the final plaster. This is what Geoff and Ellen of the Montello Alpaca Company did on their earthbag home in Nevada, in order to protect the bags as soon as possible. See this page for more photos and a video clip.
Nolan also offers this advice: If saving money was higher on the list than saving time, instead of a sprayer, I would try a slop bucket and a long bristle broom. Mix local dry clay and sand with latex paint in place of the water.
Image credit: Nolan Scheid
11 thoughts on “How to Reduce or Eliminate Tarping Earthbag Walls”
Thinking about the paint idea.
It seems as if the potential problem of latex paint would be that it becomes too slick for the finish plaster/stucco to stick.
If you were to use the lower cost/lighter weight sprayer (ceiling texture bazooka thingy) and spray a mixture of paint and fine sand, would that both protect the bags and also provide enough grit for the next plaster layer to stick?
It seems as if this would also help protect againt water too. One downside of applying an earthen slip…
Also, if I were to test this on our under construction llama barn, and it didn’t work (made it too slick) could I just correct for that by using stucco netting under the next layer?
I would rather avoid mistakes, but testing an idea that is correctable is okay….
Thanks in advance for your thoughts.
Neil Scheid, maker of the Tirolessa mortar sprayer, suggested this. It should work better than straight paint and be repairable.
@Ronin – Are you using the earthbags on the exterior of shipping containers?
@ Boxpert – I currently have a project (series of projects) that use a 40′ High Cube ISBU “CORE” with earthbags extending FROM them to form additional “wings”.
I’ve found that putting Earthbags up against a container without reinforcement of that corrugated steel siding doesn’t really work in the long term.
The methodology is pretty simple; Put all your guts (kitchen, bath, laundry facilities, HVAC) in the container and them drop it on site.
Then, using earthbags that include perlite or scoria, start building off the sides in both directions about 16′. this creates additional “space” on both sides that is easily enclosed.
Put SIPs (Structural Insulated Panels) on top of the entire kit and kaboodle with a waterproof membrane applied. Now add SSMR (Standing Seam Metal Roofing). Voila, instant energy efficient, solid as a rock, high performance 40 year roof.
Draw a big rectangle. Draw a line right down the center (top to bottom), dissecting it. That dissecting line is the ISBU. The big space on either side is the earthbag bonus!
The south side gets sliding glass doors (at least 2 sets, 3 is better) and essentially becomes a sunspace.
In this manner, (1) 40′ High Cube container will yield over 1,300 square feet. Plus, by using those earthbags and a SIP roof, you only insulate the container ENDS and the bottom.
(Okay, you insulate the bathroom and shower walls too. Otherwise, it’s kinda “musical”. Oy. :)
This represents a HUGE money (and labor!) savings when building a “DIY Castle”.
I’m talking about them on my blog and Owen and I will be talking about them here, in “play by play” mode, I suspect! ;)
This concept will likely turn into a future blog post as things take shape and the drawings get done. In the meantime, readers can check out the Reanaissance Ronin blog for more details: http://renaissanceronin.wordpress.com/
This post addresses the issue of protecting earthbag walls from UV. You also need to protect walls from rain.
Now we’re back to tarps… :)
But probably only smaller tarps along the top. A little rain on the sides shouldn’t hurt anything.
While none of our little projects rival you guys (we work primarily with ISBU shipping containers), we’ve used a modified “bazooka” (like the ones that shoot on ceiling texture) to shoot a papercrete-like mixture onto the earthbag walls at day’s end (provided the wall was “completed”.)
At the end of the week, a second shot is applied, to set up over the weekend.
It was easy, no buckets or brushes were required, the texture looked organic and cool, and clean-up was minimal. Plus, it was fun.
(Okay, as much fun as any construction task CAN be…)
Final finishing varied.
Note that most of the locations were “Arid” or high summer alpine…
It seemed to work… ;)
The texture sprayers are very similar to ones sold by MortarSprayer.com.
Yeah, but we got it on Ebay for like $29 and shipping… ;)
As I recall, in most cases we actually applied a lightweight cement plaster mixture over the papercrete, to help combat the moisture problems inherent in papercrete using the same bazooka.
(All we did was play with the air pressure.)
It stuck just fine.
As Kelly says, papercrete does soak up water like a sponge.
That last layer of plaster really did the job.