Alternative Fill Materials for Eternally Solar Earthbags

We’ve been discussing the Eternally Solar earthbag building system at length. Engineering tests show their walls exceed building code requirements even when filled with sand. Their bags are also used to form lintels and bond beams.

As exciting and practical as this is, there’s a wide range of other options. Their earthbags can be filled with different materials for optimum performance in different climates. Simply choose low cost, locally available materials that are appropriate for your situation.

Option A for cool climates: 1. insulation in outer tubes, 2. clayey subsoil in the center (for stiffening the wall), 3. sand in the inside tube for thermal mass.

Option B for cold climates: 1. scoria, pumice or perlite in outer tubes, 2. clayey subsoil mixed with scoria, pumice or perlite in the center, 3. sand in the inside tube for thermal mass.

9 thoughts on “Alternative Fill Materials for Eternally Solar Earthbags”

  1. My main question would be whether the tubes would eliminate the need for additional structure to hold rice bags in place.
    Perhaps that would need to be tested…..rice hulls in the tubes and soil in the middle.

    Thanks so much for all you have been sharing!!

    • Yes, that’s what their testing has shown. They are using some bonding courses of rebar and cement, but this may not be necessary on small structures except for lintels and bond beams.

      Rice hulls in the tubes and soil in the middle would work. Provide wide roof overhangs to prevent moisture problems.

  2. It’s more than welcome to have new and innovated materials. We don’t need to be so mean about the result at the very beginning.

  3. What would you do for hot and humid climate in Central America? There is lava rock available…. not too far away from the building site. And would beach sand be ok? It is readily available. Would the salt adversly impact the bags?

    • Beach sand can cause efflorescence because of the salt:

      It may not cause problems inside a poly bag, but you would want to experiment on a small sample and see what happens. Alternatively, you could wash the beach sand to remove as much salt as possible. But whatever you do, do not use beach sand in the plaster.

      The lava rock is an excellent choice. Use clean, crushed lava rock about 1/2″. You could use it on the inside and outside. It’s light and easy to work with so I would use this instead of sand.


Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.