Sharing information and promoting earthbag building
Questions answered by Kelly Hart
Introductory comments: Hyperadode was first introduced by its inventor, Fernando Pacheco of EcoOca in Brazil. For a better understanding of the hyperadobe concept, I suggest that you first look at this step-by-step guide to how it is done.
I am hugely impressed with this hyperadobe concept! It takes the Superadobe to a whole new level with many distinct advantages: I'm sure that the net bagging is cheaper than the woven poly material; The fill will dry out and cure faster; No need for barbed wire in vertical wall designs; More monolithic structure due to direct bonding between courses; Easier to gather the tubing on a canister for filling; Better adhesion of plaster; no need to burn off poly material to get direct bond of plaster to fill. The only disadvantage that I can think of is that it wouldn't work with some loose fill material like sand or rice hulls.
I think that even with domes, they may not need nearly as much barbed wire, because of the monolithic nature and the tensile strength that the mesh does have. In any event the mesh won't rust like we know some barbed wire has.
Comment: I am so excited about the mesh bag/tube approach and am doing tests to consider switching over entirely. I feel it is so promising. : )
Response: I agree. I think that the hyperadobe concept is the most exciting thing that has come around for some time. It really combines the best of rammed earth, cob, adobe, and earthbag, in one simple process that is faster, stronger, and cheaper than any of these. Keep me posted on your experiments.
Q: I am interested in experimenting with hyperadobe here in Spain. Would like to know which type of plastic I am supposed to use to keep the dome walls dry on the inside? Polyethylene?
A: Usually hyperadobe is done with open mesh bag material made from polyethylene that naturally breaths.
Or should it be a type of plastic which can breathe?
Q: I'm thinking of building a small place (12' x 15') with 9-10 foot walls. Would it be best for me to plan on using a fabric type tube (very small holes) or a net tube (available in ¼", 3/8" and 1/8th" holes)? What size tubes are required ( 8", 9" or 12") What quantity is required to build house?
A: The size of the mesh tubing depends upon what you are planning to fill them with. For an adobe-like soil that contains a fair amount of clay (10-35%), the 1/4" mesh should suffice. I would use the larger size (12"), as this will expand quite a bit when filled and tamped and provide a wall that is thick enough to be stable (about 14" perhaps).
Q: Do you think hyperadobe scoria roundhouses without clay or stabilizer will work if there's external pinning? I used external pinning with straw bales and the results were amazing. Also add poly strapping or baling twine tie-downs.
A: Yes, I do think that mesh tubes filled with crushed volcanic stone in roundhouses with vertical walls and exterior pinning has a good chance of working quite well. The stone would have to be large enough aggregate to not spill out of the mesh obviously.
Q: I hope to build a private house using the hyper adobe method; the only problem is sourcing Raschel or Leno weave tubing in Kenya - then came my eureka moment when I thought of Scaffold Netting which in the UK is made from Leno weave cloth !! Getting Raschel tubing from Canada was a no, due to cost - so I have sourced Scaffolding netting which is Leno weave, No stretch 50m x 3 m which I shall cut into 1m strips and have stitched into tubes and "hey presto" we have 150m of Leno Weave Tubing for £44.00 delivered.
A: I love your Eureka inspiration! Its a great idea and I hope it works. Obviously the stitching will have to be very tough, and should be as strong as the woven material itself for the concept to work. It may take some experimentation to get it right, but I trust you can do it.
Q: We want to berm and either shelter the structures or have living reciprocal roofs. Do you think hyperadobe is a viable option there? The conflicting opinions we're hearing are generally in reference to strength; we hear over and over how the hyperadobe should create an even stronger bond and therefore a stronger wall...others seem to think that the traditional poly bags with barbed wire would be stronger. What's your opinion...and even if one is probably stronger than the other, would both hold up to berming?
A: Yes, I think that hyperadobe is a viable option for these, but it is a somewhat newer technology so there are not as many examples of successful projects using the mesh. In a bermed situation I might favor the poly bags or tubes, as they would give you a somewhat better moisture barrier. In either case the bermed areas will need to carefully lined with plastic to avoid problems with moisture.
Q: I am currently working with some friends to build a hangout using the hyperadobe method. We are building in the New England area and would like to put our structure partially underground, with about 5 -6 ft of an 8 ft high wall below ground. The structure itself we plan on being around 17 ft long by 10 ft wide by 8 ft high, but depending on how much room the width of the wall takes that could change. We will be building the structure on a few layers of gravel filled bags. Can the hyperadobe method handle the stress of having to support not only a roof and at times the snow, but also the 5-6 ft of dirt weighing against it?
Q: I have a question about the mud mix for hyper adobe. I am making one and I don't think I have the mix right. I am am attempting to make it a lime stabilized mud, but so far it just crumbles to pieces. I may not have enough clay in the road base type of dirt.
A: According to the inventor of hyperadobe, "The layers of Hyperadobe begin with the soil chosen for the work, which is generally about 70% sand and 30% clay, but this can vary. It must have a good moisture content, neither too wet nor too dry, and this comes with practice." The standard for stabilizing adobe with lime is to use no more than about 7% lime, so I would suggest these guidelines for your trials.
Q: The soil here is a limestone of some sort (they use it for driveways here, like a road base). I read on your Q & A forums that it could be possible to use this material to fill the bags if it was the right size.( it seems to come in different sizes from crushed up to larger stones) Could this be used with raschel knit bags without the need for barbed wire installation? Also, there is a lot of scoria/pumice here on this island due to prior volcanic activity. Could this be used in raschel knit bags eliminating the need for barbed wire presuming I had the right size scoria or pumice?
A: It seems possible to me to use limestone in raschel tubing, in which case the crushed version with fines would probably be best, so that when it is dampened and tamped the material will bond to some extent. One of the reasons that hyperadobe works is because the material squeezes through and merges with the other bags around it, forming a somewhat monolithic wall. I don't think this would likely happen with scoria or pumice.
Q: I am considering building a hyperadobe dome. I was curious what you thought of using light straw clay as the filler for hyper adobe if possible. If it would work I assume an r value of near 28 for my 14 inch tamped walls.
A: Light straw-clay is usually tamped minimally so that it retains its airy/insulating quality. Both Hyperadobe really needs to be tamped rather thoroughly in order to function structurally, especially in a dome configuration.
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