Question from a reader:
“Owen, I have started an Earthbag storage area 19×17 as a test project for using earthbags, and I have finished the gravel section about two feet high and I have moved on to using road base, clay, and cinder. Cinder for insulation as your e-book recommends, but it is very time intensive. So, why not just build the whole thing out of gravel, just throw the gravel in the bags, I weigh each one at 80 lbs, and it’s very easy. What is the advantage of going to all that extra work and finding out the mix, weighing each element of the bag versus just doing the whole thing out of gravel?
Thanks for your replies, much appreciated.
Owen: You can use many different fill materials in the bags including gravel/rubble. See Rubble Bag Houses.
Reasons why most people use tamped earth: It’ similar to rammed earth that can last thousands of years. (Search Ancient Rammed Earth Structures on our blog.) The rammed earth is strong even without the bags, so the bags are just temporary forms so to speak. Most people can get sandy/clayey soil for free or very low cost. Gravel is typically more expensive. Gravel bags can shift just like any other loose fill material such as lava rock. That’s no problem though because there are numerous ways of stabilizing the walls: search our blog for articles on External Pinning, Buttresses, Shear Walls. You can also add cement slurry if the wall gets unstable higher up. All you need is just enough to solidify the contents.
Tip: fill the bags on the wall with the same number of buckets per bag. It’s difficult to lift heavy bags of gravel up on the wall. You will wear yourself out and get discouraged. Watch my free YouTube videos if need be.