Guide to Building with Barro; Clay Homes of Ecuador

The main building with green roof under construction.
High on a reddish-brown mountain in the Andes of southern Ecuador are most of the materials for earthen building: clay, gravel, grass and bamboo.  So the farm on this mountain, Finca Fina, is borrowing from mother nature for most of its construction.  Here´s how to build with this traditional method of the region, known as barro, Spanish for clay or mud.  Thanks to Leoncio, Oscar, Darwin, Francisco and Pablo for sharing their local wisdom.


 Benefits of this method 

  • Local, low-cost ingredients.
  • Strong – buildings last 150 years, according to Darwin, and are earthquake resistant.
  • Easy to maestro - Novice volunteers who barely understand the language are erecting artisan-level walls.
  • Fast Erections - In less than 5 weeks, a half dozen workers built one 400sq-ft structure and four smaller cabanas.
  • Energy efficient insulation - such earthen structures stay comfortable, varying only by a few degrees within their walls regardless of weather extremes beyond them.

  Ingredients and Portions
  • Clay – 20 wheelbarrows
  • Gravel – 2 wheelbarrows
  • Lime – 2 sacks, 50lbs
  • Straw – 2 sacks, dried and chopped
  • Glue – ¼ liter per bucket of water
  • Water – as needed (see methods below)

Inhaling some lime.
  Preparation
  • Mound.  Form a mound of clay while adding gravel, straw and lime.
  • Mix dry. Turn the pile once or twice until the ingredients are well blended.
  • Volcanize.  Shape the pile in spirit of Pinchincha, Cotopaxi or volcano of your choice, adding remainder of dry ingredients (see total portions).
  • Mix wet.  Stir glue into a bucket of water, pour into the volcano while turning with a rake, until final product is thoroughly moist. 

 
Leoncio and his shorts adding straw to the mound.
Adding glue/water to the volcano.

Methods
1.      Large bricks – Best for load bearing structures, such as a green roof in this case.  Use a wooden frame, insert oiled plastic liners, and pound in clay bit by bit.  Once full, slide out liners then lift away frame.

Oscar inserting oiled liners, necessary for later removal of frame.
Pounding barro to remove airpockets.
Completed block.  Gaps can be packed with clay by hand.

2.      Pack between bamboo strips – Best for lighter structures or any non-load bearing wall sections.  Split bamboo strips and nail them in horizontal rows with 2-3" gaps.  Do this on both sides of a vertical wooden frame, so there is a 3-4" hollow slot between them to be packed with barrow.  Then slap on an outer layer as well.

Francisco and Pablo nailing up the frame.
Packing in the Barro.
Completed segments from previous photo, plus bottle window.
3.      Stack with stones – Best for free form walls, an outer layer of an existing wall in this case.  Simply slop down a thick layer of barro between rows of rocks, as well as a final outer layer.


Completed wall with hole for passing firewood. 
Pointers
  • Ideal moisture depends on building method.  Clay should be thoroughly soaked where more adhesion is necessary, especially the outer coatings of methods #2 and 3.  Clay should be less  moist, almost crumbly for #1.
  • Coat adjacent timber with oil for rot protection.
  • Portions aren't set in stone.  One time we ran out of glue and continued mixing with plain water.

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