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).

A small 12 x 15 foot building with 10' walls would have less than 540 sf of wall area. Each foot of mesh might cover about .4 sf of that area...so you would need around 1,350 linear feet of the tubing. That would be quite conservative though, since it doesn't take into account any windows or doors, so perhaps 1,000 feet would do the job.

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?

A hyperadobe wall should be able to handle the weight of the roof OK, but the stress from being underground might be a challenge for the wall. This partially depends on the shape of the structure, so for instance, if it is curved and/or buttressed this can help.

Would adding concrete to the fill mix strengthen the walls?

Yes, this might help, especially since the structure will be below ground, stabilized fill is a good idea. In any event, you would need to provide a good moisture barrier.

Also I read that for stability the width of the earthbags should be at least 1/10th of the height of the wall. If that wall has to hold up 5-6 ft of dirt does that ratio change?

This is true about the ratio of width to height; and with a berm a thicker wall is better.

And if so how would you flatten the bags out more, through simple tamping?

No, you need to use larger bags.

I also understand that slanting the walls against the dirt helps to strengthen the structure but is this possible with hyperadobe?

This is absolutely true, whether with hyperadobe or standard earthbags.

How well does hyperadobe respond to prolonged direct contact with moisture that would come from being below ground.

Hyperadobe is more vulnerable to moisture than standard earthbags, and for this reason, I would recommend using regular polypropylene below grade.

We plan to put french drains and gravel around the exterior of the wall. would that be enough?

French drains, rubble trench, and gravel filled bags at the base of the wall is a good idea (another reason to use closed bags rather than open mesh).

Also where we are building its almost impossible to carry in large amounts of water to our dig site (one of the reasons we didn't go with concrete) so does that pose a problem for the bag fill for hyperadobe?

Most fill material benefits from being moistened before tamping, but it doesn't take a whole lot of water to do this.

How long does it take for the hyperadobe walls to fully dry?

A few days to a few weeks, depending on weather and soil conditions.

We were also wondering if we could build the walls in winter, or would the water in the bag fill freeze and crack the clay?

It is best to avoid freezing weather when doing this sort of work.

If so, is there any practical method of insulating the bags while they're drying.

You can cover them with blankets or tarps at night or during cold spells, but the wall needs to breath to dry out.

When ordering the raschel mesh what are the best measurements that I should ask for?

Typically a stretched diameter of about 15" is good.

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.

Q: We are building a straight walled structure with buttresses designed in about every 10 feet. I love the idea of the Hyperadobe and have sourced some rachel tubes, that seem rather stout compared. I also like the idea of using volcanic cinder rock for insulation. But now I am struggling with whether this will be structural enough? The buttresses are going to be made from the indigenous Adobe soil, and I plan to use a # of rebar stakes and was actually planning on adding some cement into the mix and wet it down after packing.

A: The reason that hyperadobe works so well with adobe soil is that the fill material does weld together when the courses are tamped together. This would not happen with scoria fill, so the advantage of the mesh is lessened. I think you are better off with bags or tubes of regular woven polypropylene and barbed wire in your case.

Q: I saw one of your videos where you use mesh bags like for onions! Its much cheaper and could be a solution. Could it work with mesh bags? 

A: I do think that you could use mesh material like that for building. The hyperadobe technique works best with long rolls of tubing, rather than individual bags, but either are possible.


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