Poured Earth Questions and Answers
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Ingredients of Poured Earth

Forming and Pouring

Cost of Poured Earth

Miscellaneous

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Ingredients of Poured Earth

Q: Can I use on-site material for my poured earth walls?

A: Yes, if on-site materials are basically low in clay (something ranging between silt to 3/8 inch aggregate). Many times we amend a site soil with off-site materials so that they meet appropriate strength and durability standards.

Q: Can I mix Portland cement with any site material and expect a strong and durable wall?

A: Probably not. Poured earth materials need to meet certifiable engineering standards. Appropriate testing needs to be done to assure a quality product Depend on testing, not luck, for a quality mix.

Q: Why use Portland Cement rather than gypsum?

A: Portland cement is water stable and gypsum is not. Therefore, while gypsum's strength will remain relatively stable in very dry environments, it's strength drops off significantly in climate where there is rain. In contrast, Portland cement becomes stronger in wet climates and is not affected by dryness.

Q: Are there other alternatives to Portland cement and gypsum?

A: Cement can be created with mixtures of flyash and lime. Also, magnesium oxide is a promising, although presently expensive, alternative.

Q: Is this an earth-friendly product if it uses Portland cement?

A: Portland cement does contribute 6-8% toward global warming (embodied energy use). However, when natural or synthetic flyash is added to the poured earth mixture, the amount of portland cement required can be reduced up to 50%. Magnesium oxide can also be used to help further reduce the use of Portland cement.

Q: My intention is to make roads from calcined gypsum, earth, road aggregates and granulated slag from iron-making  and ferro chrome production. These materials are available in plenty. Please help us to know if roads can be made from such raw materials which can withstand the running of bullock carts and light vehicles. We can understand it is difficult for people in advanced countries to know about roads in villages of India.

A: I do not work with calcined gypsum but portland cement, flyash and lime as the primary binder. Calcined gypsum is moisture sensitive as it's strength drops off substantially as moisture content increases.

Forming and Pouring

Q: Who can supply poured earth?

A: Since poured earth is a "next door neighbor" to concrete, local suppliers can provide the product which can then be pumped using traditional concrete pump trucks.

Q: I am very interested in the concept of natural building and especially in poured earth. Do you have a list of builders in the area of New England that have experience in this technique? (I live in CT)

A: If you have a project and a competent general contractor interested in building poured earth homes in you area, I could consult on your project and it would provide on the job training for your contractor. A primary thing is to have available professional concrete forming sub-contractors that do architectural grade concrete walls and like the idea of doing and providing poured earth services.

Q: Please advise on the sort of concrete pump that has been used to construct poured earth.  Any tips on mechanizing the process?

A: Any concrete pump works, small to large scale. This is a highly mechanized process. Try to work with a local concrete
redi-mix plant and pump people so you do not have to purchase equipment.

Cost of Poured Earth

Q: Do Poured Earth walls cost the same as wood frame?

A: Generally, poured earth walls increase the overall cost of construction by only 10% - 20%. However, it is important to keep in mind that frame walls have very low mass and, therefore, little ability to store heat or cooling. On the other hand, when you incorporate poured earth walls into your building project, you are also "purchasing" a large part of your heating and cooling system; one that will never break down, require maintenance, nor need to be replaced!

Q: Why does Poured Earth cost more initially?

A: Today, poured earth has been used in smaller projects like unique custom homes. Economy can only be achieved by building 20-50 homes at a time. Costs will then decrease by 10-20%.

Q: What about financing a Poured Earth home?

A: No problem. Poured earth in common terms is simply a "moderate strength concrete." Mortgage brokers and banks (as well as code officials) understand this terminology. It is important, however, to have your home certified by a structural engineer.

Q: What does it cost to certify a material?

A: The cost is generally about $1000-$2000. Testing must be done to determine shrinkage and compressive strength in order to make sure that the mix has very little, to no, shrinkage and has a compressive strength of 800-1200 psi. Accelerated weather testing is possible at an additional cost. Allow 2-3 months for testing.

Miscellaneous

Q: Is poured earth a patented or proprietary product?

A: No...the more that earth is used as a building product the better it will be for our environment! It is the goal of LSSA to make poured earth available to all who want to use it. However, it is important to do it right so as not to compromise your project. The best thing, presently, is to hire LSSA to develop the poured earth mix and to help coordinate the mixing, delivery and placing by local trades in your area. We also work on site to assure quality control for the forming and placement of the thermal break and the pouring of the walls. All of this takes place in a "training format" so that the material can be used again in your local area with little or no back up from us.

Q: What type of maintenance is necessary?

A: The answer is little to no maintenance as poured earth walls have a high resistance to the deteriorating effects of water and sun. So, enjoy some extra leisure time!

Q: How do I hang pictures and cabinets on a poured earth wall?

A: Pre-drill the wall and then use a concrete type screw which leaves a small, patchable hole. However, the color and texture variation usually visually masks any holes so little to no repair work is required.

Q: Building a small dam (2' high X 40'long) in remote and difficult to reach location.
1. Home method of testing local soil (ranges from sand to marsh muck) to determine which is best to use?
2. Any binder material (straw/grass/wood/fiber-glass) recommended?
3. Ideas on how to best work a small, wet area?
EX: Block water flow / dig out muck / pour soil cement for base / build up from that? (not sure if soil cement will set in wet ground).

A (Kelly): I would recommend that you consider using earthbags for this project. I once built a very effective dam about 6' high and 20' across using bags filled with the local soil (composition not important). It was about a yard wide at the bottom and then tapered up to about 1.5' at the top. Looking from above, it had a curved shape, with the convex side of the curve facing the water. It had strands of barbed wire running between the courses, and then was covered with 6 mil plastic sheeting to waterproof it...then lined with dry-stacked stones to protect the plastic.

C: Thanks - am using roofing tin backed by T-poles and earth for most of the dam (60' run measured today). Connections at the sand rock and dirt end is the major problem. I think some form of soil cement may be tie-end solution. Will let you know how it works out and send details. Need a good Roman engineer to let me know how they did it 2000 years ago!

Q: I am an architectural 3D rendering designer and have a project which depicts a poured earth wall which has 5 layers of color. I am looking for a good hi-res photo which I can use as a reference. Do you have anything available that you could send me?

A: Here is one: