Thursday, October 22, 2009

Earth Architecture, part 1

As we try to create a sustainable future, one of our main concerns is replacing energy inefficient buildings with new buildings that have less embodied energy and that need less energy to stay comfortable. One solution, especially in arid climates, is adobe. The Adobe Alliance has been creating adobe buildings in the American Southwest and in Mexico now for fifteen years.

I am at Adobe Alliance headquarters now near Presidio, TX, learning to build an adobe vault. Most adobe buildings in the Southwest and Mexico have regular wood roofs, but the Adobe Alliance builds houses with adobe roofs also: the roofs are Nubian vaults and domes, as described by Hassan Fathy in his book Architecture for the Poor.

Simone Swan built her house near Presidio in 1998, and that is where the Adobe Alliance is currently conducting a workshop on how to build the adobe vault. We are adding a vaulted roof to a rectangular room to the west of the Swan house.

The Nubian vault follows a catenary curve, which is the curve described by a chain if you hang it from the top of each wall of the room. Obviously this curve is upside down, but it's not hard to flip it up: first you hang the chain from the top of each wall, trace the outline of the chain onto cardboard, cut out a template along that line, and then flip the cardboard template up onto the end walls and trace its outline with a nail onto the soft adobe brick of the end walls.

Then nails are driven into the end walls along the outline of the curve, and strings are stretched between the nails to outline the curve of the vault, as a guide for the later laying of the adobe bricks.

The next few posts will show the progress of the vault as we built it over the following days.

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